OxidativeState LabsReference report
- Specimen
- Venous blood
- Population
- Adults 18+
- Panels
- 15
- Tests
- 137
- Units
- US · SI
- Updated
- Oct 18, 2026
Blood test reference ranges
Every common blood test in one place. Each row shows the usual adult range in US conventional units and in SI units, the system most labs outside the US use. Tap any test to see what it measures and what a high or low result can mean.
Your own report wins. Every lab sets its own ranges for its method and population, and many depend on age and sex. Read your result against the range printed on your report, and talk to your doctor about anything flagged. This page is education, not a diagnosis.
01 · HEM
Complete blood count
The red cells that carry oxygen, the white cells that fight infection, and the platelets that clot. The most ordered blood test in the world.
White blood cellsWBC4.0–11.0×10³/µL4.0–11.0×10⁹/L
The total number of immune cells in the blood.
H High can mean
Infection, inflammation, stress, smoking, steroid drugs, and rarely a blood cancer.
L Low can mean
Viral infection, poor nutrition (B12, folate, copper), autoimmune disease, some drugs, bone marrow problems.
Good to knowOne high reading during a cold means little. Look at which type is high in the differential below.
Red blood cellsRBCMen4.5–5.9Women4.1–5.1×10⁶/µLMen4.5–5.9Women4.1–5.1×10¹²/L
The number of red cells, which carry oxygen from the lungs to the tissues.
H High can mean
Dehydration, smoking, living at altitude, testosterone therapy, low oxygen from lung or sleep problems.
L Low can mean
Anemia from blood loss, low iron, B12 or folate, low thyroid, chronic disease, kidney disease.
HemoglobinHgbMen13.5–17.5Women12.0–15.5g/dLMen135–175Women120–155g/L
The iron-holding protein inside red cells that binds oxygen. The main number for anemia.
H High can mean
Dehydration, smoking, altitude, testosterone or EPO use, polycythemia.
L Low can mean
Anemia. The cell size (MCV) tells you which kind: small cells point to iron, large cells to B12 or folate.
Convertg/dL × 10 = g/L
Read on the siteRay Peat on iron →
HematocritHctMen41–53Women36–46%Men0.41–0.53Women0.36–0.46L/L
The share of the blood volume taken up by red cells.
H High can mean
Dehydration, testosterone therapy, smoking, polycythemia. Very high values thicken the blood.
L Low can mean
Anemia or extra fluid in the blood (pregnancy, overhydration).
Convert% ÷ 100 = L/L
Mean corpuscular volumeMCV80–100fL80–100fLSame in SI
The average size of one red cell.
H High can mean
Large cells: low B12 or folate, alcohol, liver disease, low thyroid, some drugs.
L Low can mean
Small cells: iron deficiency, thalassemia trait, chronic inflammation.
UnitsThe same number and unit in US and SI reports
Mean corpuscular hemoglobinMCH27–33pg27–33pgSame in SI
The average amount of hemoglobin in one red cell.
H High can mean
Usually moves with a high MCV (B12 or folate deficiency).
L Low can mean
Usually moves with a low MCV (iron deficiency, thalassemia trait).
UnitsThe same number and unit in US and SI reports
Mean corpuscular hemoglobin concentrationMCHC32–36g/dL320–360g/L
How concentrated the hemoglobin is inside the red cells.
H High can mean
Hereditary spherocytosis, or a sample problem (clumping, fat in the blood).
L Low can mean
Iron deficiency (pale, hypochromic cells).
Convertg/dL × 10 = g/L
Red cell distribution widthRDW11.5–14.5%11.5–14.5%Same in SI
How much red cells vary in size. An early clue before the hemoglobin falls.
H High can mean
Mixed cell sizes: early iron, B12 or folate deficiency, recent blood loss or a mixed anemia. A high RDW also tracks with higher overall risk in large studies.
L Low can mean
No known problem.
UnitsThe same number and unit in US and SI reports
PlateletsPLT150–450×10³/µL150–450×10⁹/L
The cell fragments that start a blood clot.
H High can mean
Inflammation, infection, iron deficiency, after surgery, after the spleen is removed, rarely a marrow disorder.
L Low can mean
Viral infection, alcohol, liver disease with a large spleen, some drugs, immune destruction (ITP). Below 50 bleeding risk rises.
Mean platelet volumeMPV7.5–11.5fL7.5–11.5fLSame in SI
The average size of the platelets. Young platelets are larger.
H High can mean
The marrow is making new platelets fast, as after bleeding or platelet destruction.
L Low can mean
The marrow is making fewer platelets.
UnitsThe same number and unit in US and SI reports
NeutrophilsNEUT1.8–7.7×10³/µL1.8–7.7×10⁹/L
The largest group of white cells. First responders to bacteria.
H High can mean
Bacterial infection, inflammation, physical or mental stress, cortisol or prednisone, smoking.
L Low can mean
Viral infection, B12 or folate deficiency, autoimmune disease, chemotherapy. Mildly low counts are common and harmless in people of African or Middle Eastern descent (Duffy-null).
Good to knowLabs also show each white cell type as a percent. The absolute count is the one that matters.
LymphocytesLYMPH1.0–4.8×10³/µL1.0–4.8×10⁹/L
T cells, B cells and NK cells. Viral defence and antibody production.
H High can mean
Viral infection (mono, CMV), whooping cough, chronic lymphocytic leukemia.
L Low can mean
Acute stress, high cortisol, steroid drugs, HIV, malnutrition.
MonocytesMONO0.2–0.8×10³/µL0.2–0.8×10⁹/L
White cells that become macrophages in the tissues and clean up debris.
H High can mean
Chronic infection, recovery from infection, inflammatory and autoimmune disease.
L Low can mean
Steroid drugs, some marrow problems. Rarely meaningful alone.
EosinophilsEOS0.0–0.5×10³/µL0.0–0.5×10⁹/L
White cells of allergy and parasite defence.
H High can mean
Allergy, asthma, eczema, parasites, drug reactions.
L Low can mean
Cortisol or steroid drugs, acute stress. Usually not a problem.
BasophilsBASO0.0–0.2×10³/µL0.0–0.2×10⁹/L
The rarest white cell. Carries histamine.
H High can mean
Allergic reactions, low thyroid, chronic inflammation, rarely a marrow disorder.
L Low can mean
Hard to measure at such low numbers. Not meaningful alone.
Read on the siteRay Peat on histamine →
ReticulocytesRETIC0.5–2.5%0.5–2.5%Same in SI
Young red cells just released from the marrow. Shows whether the marrow is keeping up.
H High can mean
The marrow is responding: after bleeding, red cell destruction, or a few days after starting iron or B12.
L Low can mean
The marrow is not making enough: deficiency of iron, B12 or folate, kidney disease, marrow problems.
UnitsThe same number and unit in US and SI reports
02 · CHEM
Metabolic panel
Blood sugar, salts, kidney and protein markers. The basic chemistry panel that comes with almost every check-up.
Glucose, fastingGLU70–99mg/dL3.9–5.5mmol/L
Blood sugar after at least 8 hours without food.
H High can mean
100–125 mg/dL (5.6–6.9) is prediabetes, 126 or more on two tests is diabetes. Stress, cortisol, infection and poor sleep also raise it.
L Low can mean
Below 70 mg/dL (3.9) is low blood sugar: long fasting, too much insulin or diabetes drugs, heavy alcohol, rarely an insulin-making tumor.
Convertmg/dL × 0.0555 = mmol/L
Read on the siteBlood sugar studies →Ray Peat on diabetes →
Urea nitrogenBUN7–20mg/dL2.5–7.1mmol/L urea
A waste product of protein breakdown, cleared by the kidneys.
H High can mean
Dehydration, a high-protein diet, bleeding in the stomach or gut, steroid drugs, kidney disease.
L Low can mean
Low protein intake, liver disease, overhydration, pregnancy.
Good to knowOutside the US the test is called urea. The SI value is urea in mmol/L.
Convertmg/dL × 0.357 = mmol/L
CreatinineCREAMen0.74–1.35Women0.59–1.04mg/dLMen65–119Women52–92µmol/L
A waste product of muscle, cleared by the kidneys. The main kidney filter marker.
H High can mean
Kidney disease, dehydration, a lot of muscle, creatine supplements, a meat meal or hard training the day before.
L Low can mean
Low muscle mass, pregnancy.
Good to knowMuscular people often run high with healthy kidneys. Cystatin C settles the question.
Convertmg/dL × 88.4 = µmol/L
Estimated GFReGFR90 or moremL/min/1.73m²90 or moremL/min/1.73m²Same in SI
How much blood the kidneys filter per minute, calculated from creatinine, age and sex.
H High can mean
Not a problem.
L Low can mean
60–89 is mildly reduced. Below 60 for 3 months or more is chronic kidney disease.
Good to knowIt is an estimate. It reads falsely low in muscular people. A creatinine plus cystatin C equation is more accurate.
UnitsThe same number and unit in US and SI reports
SodiumNa136–145mEq/L136–145mmol/L
The main salt in the blood. Controls water balance.
H High can mean
Dehydration, not drinking enough, rarely too much salt or a hormone problem.
L Low can mean
Drinking too much water, diuretics, SSRIs and some other drugs, low thyroid, low adrenal function, heart or liver failure.
Read on the siteRay Peat on salt →
PotassiumK3.5–5.0mEq/L3.5–5.0mmol/L
The main salt inside cells. Controls nerve and heart rhythm.
H High can mean
Kidney disease, some blood pressure drugs, or a falsely high result from a hemolysed sample.
L Low can mean
Vomiting, diarrhea, diuretics, low magnesium, high aldosterone.
Good to knowBoth high and low potassium can disturb the heart rhythm. A surprise high value is usually repeated first.
ChlorideCl98–107mEq/L98–107mmol/L
A salt that moves with sodium and helps keep the acid balance.
H High can mean
Dehydration, diarrhea, some kidney acid problems.
L Low can mean
Vomiting, diuretics, overhydration.
BicarbonateCO₂22–29mEq/L22–29mmol/L
The blood's main buffer against acid. Reported as total CO₂.
H High can mean
Vomiting, diuretics, low potassium.
L Low can mean
Acid build-up: kidney disease, diarrhea, ketoacidosis, lactic acidosis, or breathing fast.
Read on the siteRay Peat on CO₂ →
Anion gapAG7–13mEq/L7–13mmol/L
Sodium minus chloride and bicarbonate. A quick screen for hidden acids.
H High can mean
Lactic acid, ketones, kidney failure, toxins.
L Low can mean
Low albumin, rarely myeloma.
Good to knowRanges depend on the analyzer and on whether the lab adds potassium to the formula.
Calcium, totalCa8.6–10.2mg/dL2.15–2.55mmol/L
Calcium in the blood, about half of it bound to albumin.
H High can mean
Overactive parathyroid, too much vitamin D, some cancers, dehydration.
L Low can mean
Low vitamin D, low parathyroid, low magnesium, low albumin.
Good to knowIf albumin is low, total calcium reads low too. Ionized calcium is the true free amount.
Convertmg/dL × 0.2495 = mmol/L
Read on the siteRay Peat on calcium →
Calcium, ionizediCa4.6–5.3mg/dL1.15–1.33mmol/L
The free, active calcium that nerves and muscles use.
H High can mean
Overactive parathyroid, too much vitamin D.
L Low can mean
Low parathyroid, low vitamin D, low magnesium, alkalosis from fast breathing.
Convertmg/dL × 0.2495 = mmol/L
PhosphorusPHOS2.5–4.5mg/dL0.81–1.45mmol/L
Phosphate, a part of ATP and bone.
H High can mean
Kidney disease, low parathyroid, high vitamin D intake.
L Low can mean
Overactive parathyroid, refeeding after starvation, alcohol, low vitamin D, some antacids.
Convertmg/dL × 0.323 = mmol/L
MagnesiumMg1.7–2.3mg/dL0.70–0.95mmol/L
Magnesium in serum. Under 1% of the body's magnesium is in the blood.
H High can mean
Kidney failure, magnesium supplements or laxatives.
L Low can mean
Low intake, diarrhea, alcohol, diuretics, acid-blocking drugs (PPIs), diabetes.
Good to knowSerum magnesium can be normal while the cells are low. RBC magnesium is listed under vitamins and minerals.
Convertmg/dL × 0.411 = mmol/L
Read on the siteRay Peat on magnesium →Magnesium studies →
Uric acidUAMen3.4–7.0Women2.4–6.0mg/dLMen202–416Women143–357µmol/L
The end product of purine breakdown.
H High can mean
Gout risk, kidney disease, alcohol, fructose in very large amounts, diuretics, fast weight loss, fasting.
L Low can mean
Rarely a problem. Some drugs and liver disease.
Convertmg/dL × 59.48 = µmol/L
Total proteinTP6.0–8.3g/dL60–83g/L
All the proteins in serum: albumin plus globulins.
H High can mean
Dehydration, chronic inflammation, myeloma.
L Low can mean
Poor protein intake, liver disease, kidney loss, gut malabsorption.
Convertg/dL × 10 = g/L
AlbuminALB3.5–5.5g/dL35–55g/L
The main protein made by the liver. Carries hormones, drugs and fatty acids, and holds water in the vessels.
H High can mean
Dehydration.
L Low can mean
Inflammation, liver disease, kidney loss, poor intake, malabsorption.
Convertg/dL × 10 = g/L
GlobulinGLOB2.0–3.5g/dL20–35g/L
Total protein minus albumin. Mostly antibodies and transport proteins.
H High can mean
Chronic infection or inflammation, autoimmune disease, myeloma.
L Low can mean
Antibody deficiency, liver disease.
Good to knowThe albumin to globulin (A/G) ratio is usually 1.0–2.2.
Convertg/dL × 10 = g/L
Beta-hydroxybutyrateBHB< 4.2mg/dL< 0.4mmol/L
The main ketone body in the blood.
H High can mean
Fasting, low-carb or keto diets, long exercise, alcohol, uncontrolled diabetes (diabetic ketoacidosis above about 3 mmol/L).
L Low can mean
Normal on a mixed diet.
Convertmg/dL × 0.096 = mmol/L
Read on the siteLow-carb and keto studies →
Free fatty acidsFFA< 0.72mmol/L< 0.72mmol/LSame in SI
Fats released from fat tissue into the blood (non-esterified fatty acids, NEFA).
H High can mean
Fasting, stress hormones (adrenaline, cortisol), low-carb diets, uncontrolled diabetes. High levels block glucose use by the cell.
L Low can mean
After a carbohydrate meal, when insulin is up.
Good to knowRarely ordered. Must be fasting.
UnitsThe same number and unit in US and SI reports
Read on the siteGlucose vs fat →Ray Peat on PUFA →
LactateLAC6–19mg/dL0.7–2.1mmol/L
The end product of glycolysis when the cell cannot burn sugar fully in the mitochondria.
H High can mean
Hard exercise, sepsis, shock, low oxygen, metformin, thiamine deficiency, mitochondrial disease.
L Low can mean
Not a problem.
Good to knowMust be drawn at rest without a long tourniquet, and kept on ice.
Convertmg/dL × 0.111 = mmol/L
Read on the siteRay Peat on lactic acid →
AmmoniaNH₃15–45µg/dL11–32µmol/L
A toxic nitrogen waste the liver turns into urea.
H High can mean
Liver failure, some inherited enzyme problems, gut bleeding, valproate.
L Low can mean
Not a problem.
Good to knowA difficult test: the sample must go on ice and be run fast.
Convertµg/dL × 0.587 = µmol/L
OsmolalityOSM275–295mOsm/kg275–295mOsm/kgSame in SI
How concentrated the blood is.
H High can mean
Dehydration, high sugar, high sodium, alcohol or toxic alcohols.
L Low can mean
Too much water, low sodium.
UnitsThe same number and unit in US and SI reports
03 · LIV
Liver and pancreas
Enzymes that leak out of damaged cells, and bilirubin, the yellow pigment the liver clears.
Enzymes: almost every lab reports U/L. µkat/L is the strict SI unit, used mainly in Scandinavia (U/L × 0.0167).
Alanine aminotransferaseALTMen7–55Women7–45U/LMen0.12–0.92Women0.12–0.75µkat/L
An enzyme found mostly in liver cells. The most specific marker of liver cell damage.
H High can mean
Fatty liver, alcohol, hepatitis, drugs (acetaminophen, statins), hard training, celiac disease.
L Low can mean
Low B6. Not a problem.
Good to knowUpper limits differ a lot between labs (some use 40 for everyone). Many experts consider values above about 33 in men and 25 in women already worth a look.
ConvertU/L × 0.0167 = µkat/L
Read on the siteRay Peat on the liver →
Aspartate aminotransferaseAST10–40U/L0.17–0.67µkat/L
An enzyme found in liver, heart and muscle.
H High can mean
Liver damage, alcohol (AST often higher than ALT), muscle damage from training, heart damage, hemolysis.
L Low can mean
Low B6. Not a problem.
Good to knowA hard workout in the 48 hours before the test can raise AST and CK.
ConvertU/L × 0.0167 = µkat/L
Alkaline phosphataseALP30–120U/L0.50–2.00µkat/L
An enzyme from the bile ducts and from bone.
H High can mean
Blocked bile flow, bone growth (normal in teens), bone disease, low vitamin D, pregnancy.
L Low can mean
Low zinc or magnesium, low thyroid, rarely hypophosphatasia.
ConvertU/L × 0.0167 = µkat/L
Gamma-glutamyl transferaseGGTMen8–61Women5–36U/LMen0.13–1.02Women0.08–0.60µkat/L
A bile duct enzyme that also reflects oxidative stress and glutathione use.
H High can mean
Alcohol, fatty liver, blocked bile flow, some drugs. Higher GGT inside the normal range is linked to higher metabolic risk.
L Low can mean
Not a problem.
ConvertU/L × 0.0167 = µkat/L
Bilirubin, totalTBIL0.1–1.2mg/dL2–21µmol/L
The yellow pigment from old red cells, cleared by the liver.
H High can mean
Gilbert syndrome (harmless, common, rises with fasting), red cell breakdown, liver disease, blocked bile ducts.
L Low can mean
Not a problem.
Convertmg/dL × 17.1 = µmol/L
Bilirubin, directDBIL0.0–0.3mg/dL0–5µmol/L
The part of bilirubin the liver has already processed (conjugated).
H High can mean
Liver disease or blocked bile ducts. In Gilbert syndrome direct bilirubin stays normal.
L Low can mean
Not a problem.
Convertmg/dL × 17.1 = µmol/L
Lactate dehydrogenaseLDH80–225U/L1.33–3.75µkat/L
An enzyme in almost every cell that turns pyruvate into lactate.
H High can mean
Any cell damage: red cell breakdown, liver, muscle, lung, some cancers. Also a hemolysed sample.
L Low can mean
Not a problem.
Good to knowRanges differ a lot between methods (many labs use 140–280).
ConvertU/L × 0.0167 = µkat/L
AmylaseAMY25–125U/L0.42–2.08µkat/L
A starch-digesting enzyme from the pancreas and salivary glands.
H High can mean
Pancreatitis, gallstones, salivary gland problems, kidney disease.
L Low can mean
Long-term pancreas damage.
ConvertU/L × 0.0167 = µkat/L
LipaseLIP10–140U/L0.17–2.33µkat/L
A fat-digesting enzyme from the pancreas. More specific than amylase.
H High can mean
Pancreatitis (often 3 times the upper limit or more), gallstones, kidney disease, some diabetes drugs.
L Low can mean
Long-term pancreas damage, cystic fibrosis.
Good to knowRanges depend strongly on the method.
ConvertU/L × 0.0167 = µkat/L
04 · REN
Kidney extras
Two tests that catch kidney trouble earlier and more accurately than creatinine alone.
Cystatin CCYSCAge 18–490.63–1.03Age 50+0.67–1.21mg/LAge 18–490.63–1.03Age 50+0.67–1.21mg/LSame in SI
A small protein made by every cell and filtered by the kidneys. Unlike creatinine, muscle mass does not change it.
H High can mean
Reduced kidney filtering. High thyroid and steroid drugs raise it a little.
L Low can mean
Not a problem.
Good to knowUse it when creatinine is borderline in a muscular person or someone taking creatine.
UnitsThe same number and unit in US and SI reports
Urine albumin to creatinine ratioUACR< 30mg/g< 3mg/mmol
Albumin leaking into the urine, the earliest sign of kidney damage from diabetes or high blood pressure.
H High can mean
30–300 mg/g is moderately increased, above 300 severely increased. Hard exercise, fever and infection raise it for a day or two.
L Low can mean
Normal.
Good to knowA spot urine sample. One high result needs repeating, 2 of 3 positive over 3–6 months confirms it.
Convertmg/g × 0.113 = mg/mmol
05 · LIP
Lipids and heart risk
The particles that carry fat and cholesterol in the blood. These are targets, not population averages: the numbers are the levels guidelines call desirable.
Total cholesterolCHOL< 200mg/dL< 5.2mmol/L
All the cholesterol in the blood, carried in LDL, HDL and VLDL.
H High can mean
200–239 mg/dL is borderline, 240 or more is high. Low thyroid raises cholesterol, so do some genes.
L Low can mean
Overactive thyroid, liver disease, infection, malnutrition, statins. Cholesterol is the raw material for every steroid hormone, so very low values are not a goal.
Convertmg/dL × 0.0259 = mmol/L
Read on the siteRay Peat on cholesterol →Steroids 101 →
LDL cholesterolLDL-C< 100mg/dL< 2.6mmol/L
Cholesterol carried in low-density lipoprotein, the particle that delivers cholesterol to tissues.
H High can mean
130–159 borderline, 160–189 high, 190 or more very high (think of familial hypercholesterolemia). Low thyroid slows LDL clearance.
L Low can mean
Statins, hyperthyroidism, malnutrition, rare genes.
Good to knowOften calculated, not measured. The calculation fails when triglycerides are high.
Convertmg/dL × 0.0259 = mmol/L
HDL cholesterolHDL-CMen> 40Women> 50mg/dLMen> 1.0Women> 1.3mmol/L
Cholesterol carried back to the liver.
H High can mean
Usually good. Very high values (above about 100) are not extra protective.
L Low can mean
Insulin resistance, high triglycerides, smoking, inactivity, anabolic steroids.
Convertmg/dL × 0.0259 = mmol/L
TriglyceridesTG< 150mg/dL< 1.7mmol/L
Fat carried in the blood as triglyceride.
H High can mean
Insulin resistance, alcohol, a recent meal, low thyroid, some drugs. Above 500 mg/dL raises pancreatitis risk.
L Low can mean
Usually fine.
Good to knowA triglyceride to HDL ratio (mg/dL) above about 3 hints at insulin resistance.
Convertmg/dL × 0.0113 = mmol/L
Non-HDL cholesterolnon-HDL< 130mg/dL< 3.4mmol/L
Total cholesterol minus HDL: all the cholesterol in the particles that can enter the artery wall.
H High can mean
Same causes as high LDL and high triglycerides.
L Low can mean
Usually fine.
Good to knowWorks without fasting. Many guidelines prefer it to LDL.
Convertmg/dL × 0.0259 = mmol/L
Apolipoprotein BApoB< 90mg/dL< 0.9g/L
One ApoB protein sits on every LDL and VLDL particle, so this counts the particles directly.
H High can mean
90–119 mg/dL is borderline, 120–139 high, 140 or more very high. More particles that can enter the artery wall. Often high in insulin resistance even when LDL looks normal.
L Low can mean
Usually fine.
Convertmg/dL × 0.01 = g/L
Lipoprotein(a)Lp(a)< 30mg/dL< 75nmol/L
An LDL-like particle with an extra protein attached. Its level is set almost entirely by genes.
H High can mean
Higher lifelong risk of heart disease and aortic valve narrowing. Above 50 mg/dL (125 nmol/L) is high.
L Low can mean
Not a problem.
Good to knowCheck it once in a lifetime. mg/dL and nmol/L cannot be converted exactly, because the particle size differs between people.
High-sensitivity CRPhs-CRP< 1.0mg/L< 9.5nmol/L
A liver protein that rises with low-grade inflammation. Used for heart risk.
H High can mean
1–3 mg/L average risk, above 3 high risk. Above 10 means an infection or injury, so repeat it in 2 weeks.
L Low can mean
Low inflammation.
Convertmg/L × 9.52 = nmol/L
Read on the siteRay Peat on inflammation →
HomocysteineHCY5–15µmol/L5–15µmol/LSame in SI
An amino acid made from methionine. B12, folate and B6 clear it.
H High can mean
Low B12, folate or B6, kidney disease, low thyroid, MTHFR gene variants, some drugs (metformin, PPIs). Linked to heart and brain risk.
L Low can mean
Rarely a problem.
Good to knowMany clinicians aim for below about 10 µmol/L.
UnitsThe same number and unit in US and SI reports
Read on the siteB vitamin studies →
06 · GLY
Blood sugar control
Fasting glucose shows one moment. These show the average sugar over months and how hard the pancreas works to keep it there.
Hemoglobin A1cHbA1c4.0–5.6%20–38mmol/mol
The share of hemoglobin with sugar stuck to it. Shows the average blood sugar of the last 2–3 months.
H High can mean
5.7–6.4% (39–47 mmol/mol) is prediabetes, 6.5% (48) or more is diabetes.
L Low can mean
Anything that shortens red cell life: blood loss, hemolysis, recent transfusion. Iron deficiency raises it falsely.
Good to knowThe % is the US (NGSP) unit. mmol/mol is the international (IFCC) unit used in the UK, Europe and Australia. Many labs print both.
Convertmmol/mol = (% − 2.15) × 10.929
Read on the siteBlood sugar studies →
Insulin, fastingINS2.6–24.9µIU/mL18–173pmol/L
The hormone that moves sugar into cells. A high fasting value with normal glucose is the first sign of insulin resistance.
H High can mean
Insulin resistance, obesity, high stress hormones, rarely an insulin-making tumor.
L Low can mean
Type 1 diabetes or a tired pancreas.
Good to knowThe lab range is wide and depends on the method. There is no agreed cut-off for insulin resistance, but many clinicians want fasting insulin below about 10 µIU/mL.
ConvertµIU/mL × 6.945 = pmol/L (some labs use 6.0)
Read on the siteVitamin E and insulin resistance →
HOMA-IRHOMA< 2.0index< 2.0indexSame in SI
A calculation from fasting glucose and insulin: glucose (mg/dL) × insulin ÷ 405.
H High can mean
Above about 2 suggests insulin resistance, above 2.9 is clear insulin resistance in most studies.
L Low can mean
Good insulin sensitivity.
Good to knowWith SI units: glucose (mmol/L) × insulin (µIU/mL) ÷ 22.5. Cut-offs differ between populations.
UnitsThe same number and unit in US and SI reports
C-peptideCPEP0.8–3.1ng/mL0.26–1.03nmol/L
A piece cut off when the pancreas makes insulin. Shows your own insulin output, even if you inject insulin.
H High can mean
Insulin resistance, kidney disease.
L Low can mean
Type 1 diabetes, a tired pancreas.
Convertng/mL × 0.331 = nmol/L
FructosamineFRUC200–285µmol/L200–285µmol/LSame in SI
Sugar stuck to blood proteins. Shows the average blood sugar of the last 2–3 weeks.
H High can mean
Higher average blood sugar.
L Low can mean
Low albumin.
Good to knowUseful when A1c cannot be trusted (anemia, pregnancy, recent blood loss). Ranges differ between labs.
UnitsThe same number and unit in US and SI reports
07 · THY
Thyroid
The thyroid sets the metabolic rate of every cell. TSH is the brain's signal, T4 the storage form, T3 the active hormone.
Thyroid stimulating hormoneTSH0.4–4.5mIU/L0.4–4.5mIU/LSame in SI
The pituitary's signal to the thyroid. It rises when thyroid hormone is low.
H High can mean
Low thyroid (hypothyroidism), Hashimoto's, recovery from illness, low iodine.
L Low can mean
Overactive thyroid, too much thyroid medication, rarely a pituitary problem.
Good to knowSame number in µIU/mL. The upper limit differs by lab and age (4.0 to 4.5). TSH is highest at night and early morning. Many clinicians want it below about 2.5.
UnitsThe same number and unit in US and SI reports
Read on the siteRay Peat on thyroid →Thyroid studies →Temperature and pulse →
Free T4FT40.8–1.8ng/dL10–23pmol/L
The unbound storage hormone. The body turns it into active T3 in the liver and other tissues.
H High can mean
Overactive thyroid, taking T4 (levothyroxine) shortly before the test, biotin interference.
L Low can mean
Low thyroid, or low pituitary output if TSH is not high.
Good to knowStop biotin for 2 days before thyroid tests: it distorts many immunoassays.
Convertng/dL × 12.87 = pmol/L
Free T3FT32.3–4.2pg/mL3.5–6.5pmol/L
The unbound active thyroid hormone, the one that drives cell metabolism.
H High can mean
Overactive thyroid, T3 medication.
L Low can mean
Low thyroid, poor conversion from T4 (fasting, low-carb diets, stress, illness, low selenium).
Convertpg/mL × 1.536 = pmol/L
Read on the siteTake control of your metabolic rate →
Total T4TT45.0–12.0µg/dL64–154nmol/L
All the T4, bound and free.
H High can mean
Overactive thyroid, estrogen or the pill and pregnancy (more binding protein).
L Low can mean
Low thyroid, low binding protein.
Convertµg/dL × 12.87 = nmol/L
Total T3TT380–180ng/dL1.2–2.8nmol/L
All the T3, bound and free.
H High can mean
Overactive thyroid, more binding protein.
L Low can mean
Low thyroid, illness, fasting, very low carbohydrate intake.
Convertng/dL × 0.0154 = nmol/L
Reverse T3rT310–24ng/dL0.15–0.37nmol/L
An inactive form of T3 made from T4. The body makes more of it to slow metabolism down.
H High can mean
Illness, fasting and calorie restriction, high cortisol, liver problems, high doses of T4.
L Low can mean
Not a problem.
Good to knowAssays differ: some labs print about 20–40 ng/dL. Compare only results from the same lab.
Convertng/dL × 0.0154 = nmol/L
Thyroid peroxidase antibodiesTPO Ab< 9IU/mL< 9IU/mLSame in SI
Antibodies against the thyroid's iodine enzyme. The marker of Hashimoto's.
H High can mean
Hashimoto's or Graves' disease. Positive antibodies with normal TSH raise the chance of low thyroid later.
L Low can mean
Normal.
Good to knowThe cut-off depends on the assay: others use < 35 IU/mL. Results from different kits are not interchangeable.
UnitsThe same number and unit in US and SI reports
Thyroglobulin antibodiesTgAb< 4IU/mL< 4IU/mLSame in SI
Antibodies against thyroglobulin, the protein T4 is made on.
H High can mean
Hashimoto's, Graves' disease. Also checked after thyroid cancer because they disturb the thyroglobulin test.
L Low can mean
Normal.
Good to knowStrongly assay dependent: some labs use < 115 IU/mL.
UnitsThe same number and unit in US and SI reports
ThyroglobulinTg1.5–38.5ng/mL1.5–38.5µg/L
The protein the thyroid builds its hormones on.
H High can mean
Goiter, thyroid inflammation, Graves', return of thyroid cancer after surgery.
L Low can mean
After thyroid removal, or taking thyroid hormone.
Good to knowAssay dependent. Thyroglobulin antibodies make the result unreliable.
08 · AND
Male hormones
Testosterone peaks in the morning and drops after meals, so test before 10 am and before breakfast. Some of these are also measured in women (shown).
Testosterone, totalTTMen264–916Women18–54ng/dLMen9.2–31.8Women0.6–1.9nmol/L
All the testosterone in the blood, bound to SHBG and albumin plus the free part.
H High can mean
Men: testosterone use. Women: PCOS, adrenal problems, androgen-making tumors.
L Low can mean
Men: obesity, poor sleep, low calories, opioids, high prolactin, pituitary or testicular problems, aging.
Good to knowThe male range is the CDC-harmonized range for healthy non-obese men aged 19–39 (Travison 2017). Other labs use about 240–950 or 290–1100. Repeat a low value on a second morning before deciding anything.
Convertng/dL × 0.0347 = nmol/L
Read on the siteTestosterone and DHT studies →Steroids 101 →
Testosterone, freeFTMen50–210Women1.0–8.5pg/mLMen174–729Women3.5–29.5pmol/L
The unbound part that can enter cells, about 2% of the total.
H High can mean
Testosterone use, low SHBG (insulin resistance, low thyroid).
L Low can mean
Low total testosterone or high SHBG.
Good to knowThe men's range is for young adults and falls with age. Direct analog free testosterone tests are unreliable. Equilibrium dialysis or a calculation from total T, SHBG and albumin is better.
Convertpg/mL × 3.467 = pmol/L
Sex hormone binding globulinSHBGMen10–57Women18–144nmol/LMen10–57Women18–144nmol/LSame in SI
The liver protein that binds testosterone and estradiol and holds them inactive.
H High can mean
Estrogen, the pill, high thyroid, aging, liver disease, low calories. Leaves less free testosterone.
L Low can mean
Insulin resistance, obesity, low thyroid, anabolic steroids, PCOS.
UnitsThe same number and unit in US and SI reports
Read on the siteMicroplastics and testosterone →
DihydrotestosteroneDHTMen25–80Women4–22ng/dLMen0.86–2.75Women0.14–0.76nmol/L
The strongest androgen, made from testosterone by 5-alpha reductase in skin, scalp and prostate.
H High can mean
Testosterone therapy. Linked to scalp hair loss and prostate growth in men who are prone to them.
L Low can mean
Finasteride or dutasteride, low testosterone.
Convertng/dL × 0.0344 = nmol/L
Read on the siteHow to increase DHT →DHT blocker side effects →
Estradiol (men)E210–40pg/mL37–147pmol/L
The main estrogen. Men make it from testosterone through aromatase, mostly in fat tissue.
H High can mean
Obesity, testosterone therapy, liver disease, alcohol, some drugs.
L Low can mean
Aromatase inhibitors, very low testosterone. Too low hurts bone and libido.
Good to knowOrder the sensitive (LC-MS/MS) estradiol test for men. Standard tests are built for women's levels.
Convertpg/mL × 3.671 = pmol/L
Read on the siteHigh estrogen in men →Estrogen studies →
Prostate specific antigenPSA< 4.0ng/mL< 4.0µg/L
A protein made by the prostate.
H High can mean
Enlarged prostate, prostatitis, prostate cancer, recent ejaculation or a long bike ride.
L Low can mean
Finasteride and dutasteride halve it.
Good to knowAge-based upper limits: 2.0 under 40, 2.5 in the 40s, 3.5 in the 50s, 4.5 in the 60s, 6.5 in the 70s. A rise over time matters more than one value.
Luteinizing hormone (men)LH2–9IU/L2–9IU/LSame in SI
The pituitary signal that tells the testes to make testosterone.
H High can mean
With low testosterone: the testes are failing (primary hypogonadism).
L Low can mean
With low testosterone: the pituitary is not signalling (secondary). Testosterone or steroid use shuts LH down.
Good to knowSame number in mIU/mL.
UnitsThe same number and unit in US and SI reports
Follicle stimulating hormone (men)FSH1–7IU/L1–7IU/LSame in SI
The pituitary signal for sperm production.
H High can mean
Testicular damage, low sperm production.
L Low can mean
Pituitary problem, testosterone or steroid use.
Good to knowSame number in mIU/mL.
UnitsThe same number and unit in US and SI reports
Read on the siteFertility studies →
09 · GYN
Female hormones
Women's ranges move through the cycle. Day 2–5 is the standard day for FSH, LH and estradiol, about day 21 (7 days before the period) for progesterone.
Estradiol (women)E2Follicular10–180Mid-cycle100–300Luteal40–200After menopause< 10pg/mLFollicular37–661Mid-cycle367–1101Luteal147–734After menopause< 37pmol/L
The main estrogen, made by the ovaries.
H High can mean
Ovulation (normal), ovarian cysts, estrogen therapy, obesity after menopause.
L Low can mean
Menopause, low body fat or under-eating, heavy training, pituitary problems.
Good to knowPhase ranges differ between labs and between immunoassay and LC-MS/MS methods.
Convertpg/mL × 3.671 = pmol/L
Read on the siteRay Peat on estrogen →Estrogen studies →
ProgesteronePROGFollicular< 0.9Luteal2–30After menopause< 0.5Men0.1–0.3ng/mLFollicular< 2.9Luteal6.4–95After menopause< 1.6Men0.4–1.0nmol/L
The hormone of the second half of the cycle, made after ovulation. Balances estrogen.
H High can mean
Ovulation happened, pregnancy, progesterone supplements.
L Low can mean
No ovulation that cycle, short luteal phase, menopause, high stress.
Good to knowA day-21 value above about 3 ng/mL (10 nmol/L) shows ovulation took place.
Convertng/mL × 3.18 = nmol/L
Read on the siteRay Peat on progesterone →
Luteinizing hormone (women)LHFollicular and luteal1–12Mid-cycle peak9–80After menopause> 30IU/LFollicular and luteal1–12Mid-cycle peak9–80After menopause> 30IU/LSame in SI
The pituitary signal that triggers ovulation.
H High can mean
Ovulation surge (normal), PCOS (LH often twice FSH), menopause.
L Low can mean
Pituitary problems, under-eating, heavy training, high prolactin.
Good to knowSame number in mIU/mL.
UnitsThe same number and unit in US and SI reports
Follicle stimulating hormone (women)FSHFollicular and luteal2–9Mid-cycle peak4–22After menopause> 30IU/LFollicular and luteal2–9Mid-cycle peak4–22After menopause> 30IU/LSame in SI
The pituitary signal that grows the egg follicles.
H High can mean
Menopause, falling egg reserve.
L Low can mean
Pituitary problems, pregnancy, under-eating.
Good to knowSame number in mIU/mL. Day 2–5 FSH above about 10 suggests a lower egg reserve.
UnitsThe same number and unit in US and SI reports
Anti-Müllerian hormoneAMHAge 25–290.89–9.9Age 30–340.58–8.1Age 35–390.15–7.5Age 40–440.03–5.5ng/mLAge 25–296.4–70.7Age 30–344.1–57.8Age 35–391.1–53.6Age 40–440.2–39.3pmol/L
A hormone from the small follicles in the ovary. An estimate of the remaining egg reserve.
H High can mean
PCOS (many small follicles).
L Low can mean
Lower egg reserve, approaching menopause, after ovary surgery or chemotherapy.
Good to knowCan be drawn on any day of the cycle. It does not predict natural fertility well in the short term. Ranges differ by assay.
Convertng/mL × 7.14 = pmol/L
Testosterone (women)TT18–54ng/dL0.6–1.9nmol/L
Women make small amounts in the ovaries and adrenals. It supports libido, muscle and mood.
H High can mean
PCOS, adrenal problems, androgen-making tumors (very high values).
L Low can mean
The pill, menopause, removal of the ovaries.
Convertng/dL × 0.0347 = nmol/L
hCGhCG< 5mIU/mL< 5IU/L
The pregnancy hormone.
H High can mean
Pregnancy (usually above 25), some tumors.
L Low can mean
Not pregnant.
Good to know5–25 is a grey zone: repeat in 48 hours.
10 · ADR
Adrenal, pituitary and stress
The stress axis: the brain's ACTH drives cortisol from the adrenals. Prolactin and growth hormone come from the same gland.
Cortisol, morningCORT5–25µg/dL138–690nmol/L
The main stress hormone. Peaks about 30 minutes after waking, lowest around midnight.
H High can mean
Stress, poor sleep, the pill (more binding protein), steroid drugs, Cushing's (needs special tests).
L Low can mean
Adrenal insufficiency (Addison's), coming off steroid drugs, pituitary problems.
Good to knowOnly a morning sample makes sense. A morning value below about 3 µg/dL (83 nmol/L) points to adrenal insufficiency.
Convertµg/dL × 27.59 = nmol/L
Read on the siteRay Peat on cortisol →How to lower cortisol →Cortisol studies →
ACTHACTH7.2–63pg/mL1.6–13.9pmol/L
The pituitary hormone that drives cortisol.
H High can mean
Addison's disease (the adrenals do not answer), stress, rarely a pituitary tumor.
L Low can mean
Steroid drugs, pituitary problems.
Good to knowMust go on ice. Read together with cortisol drawn at the same time.
Convertpg/mL × 0.22 = pmol/L
DHEA sulfateDHEA-SMen89–457Women44–332µg/dLMen2.4–12.4Women1.2–9.0µmol/L
The main adrenal androgen in the blood. Peaks in the 20s and falls about 2% a year.
H High can mean
PCOS, DHEA supplements, adrenal tumors (very high).
L Low can mean
Aging, adrenal insufficiency, steroid drugs, chronic illness.
Good to knowStrongly age based: at 18–30 the range is higher (about 105–728 in men, 83–377 in women). Always compare with the range for your age on the report.
Convertµg/dL × 0.0271 = µmol/L
Read on the siteDHEA for men →Cortisol to DHEA ratio →Ray Peat on pregnenolone and DHEA →
ProlactinPRLMen4.0–15.2Women4.8–23.3ng/mLMen85–322Women102–494mIU/L
The milk hormone from the pituitary. Dopamine holds it down; estrogen and serotonin push it up.
H High can mean
Stress, poor sleep, low thyroid, estrogen, SSRIs and antipsychotics, opioids, a pituitary adenoma (prolactinoma).
L Low can mean
Rarely a problem. Dopamine drugs lower it.
Good to knowDraw it at rest, at least 2–3 hours after waking. Exercise, sex and nipple stimulation raise it for a while.
Convertng/mL × 21.2 = mIU/L
Read on the siteHow to lower prolactin →Prolactin, the anti-life hormone →Prolactin and dopamine studies →
Insulin-like growth factor 1IGF-1Age 16–24182–780Age 25–39114–492Age 40–5490–360Age 55+71–290ng/mLAge 16–2423.8–102Age 25–3914.9–64.4Age 40–5411.8–47.2Age 55+9.3–38.0nmol/L
Made by the liver in answer to growth hormone. A stable stand-in for growth hormone, which comes in pulses.
H High can mean
Growth hormone use, acromegaly, puberty, high protein intake.
L Low can mean
Growth hormone deficiency, low calories, low protein, liver disease, low thyroid, aging.
Good to knowRanges are age based and assay based. Compare with the lab's range for your age.
Convertng/mL × 0.131 = nmol/L
Read on the siteRay Peat on growth hormone →
AldosteroneALDOLying or seated≤ 10Standing≤ 21ng/dLLying or seated≤ 277Standing≤ 582pmol/L
The adrenal salt hormone. Holds sodium, sends potassium out.
H High can mean
Low salt intake, dehydration, primary aldosteronism (a common hidden cause of high blood pressure).
L Low can mean
High salt intake, adrenal insufficiency.
Good to knowDepends on posture and salt intake. Usually ordered with renin as a ratio.
Convertng/dL × 27.7 = pmol/L
Read on the siteRay Peat on salt →
Parathyroid hormonePTH10–65pg/mL1.1–6.9pmol/L
The hormone that keeps blood calcium up by pulling it from bone and activating vitamin D.
H High can mean
Low vitamin D or calcium intake, an overactive parathyroid gland, kidney disease.
L Low can mean
Too much calcium or vitamin D, a parathyroid that was removed or damaged.
Good to knowRead with calcium and vitamin D drawn at the same time.
Convertpg/mL × 0.106 = pmol/L
Read on the siteThe calcium paradox →
11 · FE
Iron
Iron carries oxygen, but free iron also drives oxidation. Ferritin shows the store, transferrin saturation shows what is in transit.
FerritinFERRMen24–336Women11–307ng/mLMen24–336Women11–307µg/L
The iron storage protein. The best single measure of iron stores.
H High can mean
Iron overload (hemochromatosis), inflammation and infection, fatty liver, alcohol. Ferritin rises with inflammation even when iron is normal.
L Low can mean
Iron deficiency. It drops before hemoglobin falls.
Good to knowMany clinicians treat a ferritin below about 30 as low iron even when the lab says normal.
Read on the siteRay Peat on iron →
Iron, serumFe50–150µg/dL9–27µmol/L
Iron in transit in the blood.
H High can mean
Iron supplements, overload, liver damage.
L Low can mean
Iron deficiency, inflammation.
Good to knowSwings a lot through the day and after meals. Never judge iron on this number alone.
Convertµg/dL × 0.179 = µmol/L
Total iron binding capacityTIBC250–450µg/dL45–81µmol/L
How much iron the blood's transferrin could carry.
H High can mean
Iron deficiency, pregnancy, the pill.
L Low can mean
Iron overload, inflammation, low protein.
Good to knowRanges differ a lot between labs (some use 250–370).
Convertµg/dL × 0.179 = µmol/L
Transferrin saturationTSAT20–50%0.20–0.50fraction
Serum iron divided by TIBC: how full the transport protein is.
H High can mean
Above 45% on a fasting test is the first screen for hemochromatosis.
L Low can mean
Below 20% means too little iron is reaching the tissues.
TransferrinTRF200–400mg/dL2.0–4.0g/L
The protein that carries iron in the blood.
H High can mean
Iron deficiency, pregnancy, estrogen.
L Low can mean
Inflammation, malnutrition, liver disease, iron overload.
Convertmg/dL × 0.01 = g/L
12 · VIT
Vitamins and minerals
Most of these are not in a routine panel and must be asked for by name.
Vitamin D, 25-hydroxy25-OH D30–100ng/mL75–250nmol/L
The storage form of vitamin D. Reflects sun and supplement intake over the last weeks.
H High can mean
Above 100 ng/mL (250 nmol/L) is high, above about 150 can be toxic (high calcium). Almost always from large supplement doses.
L Low can mean
Below 20 ng/mL (50 nmol/L) is deficient, 20–29 insufficient. Little sun, dark skin, obesity, malabsorption.
Good to knowThe 30 ng/mL lower limit is the Endocrine Society's (2011). The Institute of Medicine and Mayo call 20 ng/mL (50 nmol/L) enough.
Convertng/mL × 2.496 = nmol/L
Read on the siteVitamin K2 and D3 →Vitamin D studies →Ray Peat on vitamins A, D and K →
Vitamin B12B12200–800pg/mL148–590pmol/L
Cobalamin. Needed for nerves, DNA and red cells.
H High can mean
Supplements or injections, liver disease, some blood disorders.
L Low can mean
Vegan diet, low stomach acid, PPIs, metformin, pernicious anemia, older age.
Good to know200–400 pg/mL is a grey zone: methylmalonic acid and homocysteine show whether it is low in the tissues.
Convertpg/mL × 0.738 = pmol/L
Read on the siteB vitamin studies →
Folate, serumFOL2.7–17.0ng/mL6.1–38.5nmol/L
Vitamin B9 in the blood. Reflects recent intake.
H High can mean
Supplements, fortified foods.
L Low can mean
Low intake of greens, alcohol, pregnancy, methotrexate and some anti-seizure drugs.
Convertng/mL × 2.266 = nmol/L
Folate, red cellRBC FOL> 140ng/mL> 317nmol/L
Folate stored in red cells. Reflects intake over about 3 months.
H High can mean
Supplements.
L Low can mean
Long-term low intake.
Convertng/mL × 2.266 = nmol/L
Vitamin B1 (thiamine)TDP30–77µg/L70–180nmol/L
Thiamine diphosphate in whole blood, the active form the mitochondria need to burn sugar.
H High can mean
Supplements. Not harmful.
L Low can mean
Alcohol, poor diet, vomiting, after bariatric surgery, diuretics, high sugar intake with low B1.
Good to knowThe whole-blood TDP test is the reliable one. Serum thiamine is not.
Convertµg/L × 2.35 = nmol/L
Read on the siteThiamine (B1) benefits →
Vitamin B6 (PLP)PLP5–50µg/L20–202nmol/L
Pyridoxal 5-phosphate, the active B6.
H High can mean
Supplements, sometimes from energy drinks or multis. Long-term very high levels can damage nerves.
L Low can mean
Alcohol, kidney disease, inflammation, some drugs.
Convertµg/L × 4.046 = nmol/L
Vitamin A (retinol)VIT A32.5–78.0µg/dL1.13–2.72µmol/L
Retinol in the blood. Needed for vision, skin and the thyroid.
H High can mean
Supplements or liver eaten often, kidney disease. Too much is toxic.
L Low can mean
Low intake, fat malabsorption, liver disease, low zinc.
Convertµg/dL × 0.0349 = µmol/L
Read on the siteRay Peat on vitamins A, D and K →
Vitamin E (alpha-tocopherol)VIT E5.5–17.0mg/L12.8–39.5µmol/L
The main fat-soluble antioxidant in cell membranes.
H High can mean
Supplements, high blood lipids.
L Low can mean
Fat malabsorption, a diet low in vitamin E and high in PUFA.
Good to knowIt rises with cholesterol and triglycerides, so some labs report it as a ratio to lipids.
Convertmg/L × 2.322 = µmol/L
Read on the siteGamma vs alpha tocopherol →Vitamin E studies →Vitamin E guide →
Vitamin K1VIT K0.10–2.20ng/mL0.22–4.88nmol/L
Phylloquinone from leafy greens. Needed for clotting and for proteins that keep calcium in bone.
H High can mean
Supplements, greens eaten before the test.
L Low can mean
Low intake, fat malabsorption, antibiotics, warfarin.
Good to knowReflects the last day's food. PT/INR shows the clotting effect.
Convertng/mL × 2.22 = nmol/L
Vitamin CVIT C0.4–1.5mg/dL23–85µmol/L
Ascorbic acid in plasma.
H High can mean
Supplements.
L Low can mean
Low fruit and vegetable intake, smoking, stress, illness. Below 0.2 mg/dL (11 µmol/L) is deficient.
Convertmg/dL × 56.8 = µmol/L
Methylmalonic acidMMA< 0.40µmol/L< 0.40µmol/LSame in SI
Builds up when B12 is low inside the cells. The most specific test for B12 deficiency.
H High can mean
B12 deficiency, kidney disease.
L Low can mean
Normal.
UnitsThe same number and unit in US and SI reports
ZincZn60–120µg/dL9.2–18.4µmol/L
A mineral used by hundreds of enzymes, including those for testosterone, thyroid and immune cells.
H High can mean
Supplements. Long-term high zinc lowers copper.
L Low can mean
Low intake, high-phytate diets, gut malabsorption, alcohol, inflammation.
Good to knowMorning, fasting, in a trace-element tube. Inflammation lowers it.
Convertµg/dL × 0.153 = µmol/L
CopperCuMen70–140Women80–155µg/dLMen11.0–22.0Women12.6–24.3µmol/L
A mineral needed for iron handling, energy production (cytochrome c oxidase) and collagen.
H High can mean
Estrogen, the pill, pregnancy, inflammation.
L Low can mean
Too much zinc, gut malabsorption, after bariatric surgery, Wilson disease.
Convertµg/dL × 0.157 = µmol/L
CeruloplasminCP20–35mg/dL200–350mg/L
The protein that carries copper and helps load iron onto transferrin.
H High can mean
Estrogen, pregnancy, inflammation.
L Low can mean
Wilson disease, copper deficiency, liver disease.
Convertmg/dL × 10 = mg/L
SeleniumSe110–165ng/mL1.39–2.09µmol/L
A mineral needed by the enzymes that activate thyroid hormone and by glutathione peroxidase.
H High can mean
Supplements or Brazil nuts. Very high intake is toxic (hair and nail loss).
L Low can mean
Low-selenium soils, malabsorption.
Convertng/mL × 0.0127 = µmol/L
Magnesium, red cellRBC Mg4.2–6.8mg/dL1.73–2.80mmol/L
Magnesium inside red cells. Closer to the body's stores than serum magnesium.
H High can mean
Supplements, kidney disease.
L Low can mean
Low intake, stress, alcohol, diuretics, PPIs.
Good to knowNot standardised: there is no agreed reference range, so every lab uses its own.
Convertmg/dL × 0.411 = mmol/L
Read on the siteMagnesium studies →
13 · INF
Inflammation, heart and clotting
Markers of inflammation, of strain on the heart, and of how fast the blood clots.
C-reactive proteinCRP< 0.8mg/dL< 8mg/L
The standard CRP test, for infection and inflammation. For heart risk use hs-CRP in the lipid panel.
H High can mean
Infection (bacterial often above 10 mg/dL), injury, surgery, autoimmune flares.
L Low can mean
Normal.
Convertmg/dL × 10 = mg/L
Erythrocyte sedimentation rateESRMen0–15Women0–20mm/hMen0–15Women0–20mm/hSame in SI
How fast red cells settle in a tube. An old, slow-moving inflammation test.
H High can mean
Inflammation, infection, autoimmune disease, anemia, pregnancy, older age, myeloma.
L Low can mean
Not meaningful.
Good to knowUpper limit rises with age: roughly age ÷ 2 for men, (age + 10) ÷ 2 for women.
UnitsThe same number and unit in US and SI reports
FibrinogenFIB200–400mg/dL2.0–4.0g/L
A clotting protein that also rises with inflammation.
H High can mean
Inflammation, infection, smoking, pregnancy, estrogen. Linked to heart risk.
L Low can mean
Liver disease, bleeding disorders, clots using it up (DIC).
Convertmg/dL × 0.01 = g/L
NT-proBNPNT-proBNP< 125pg/mL< 125ng/L
A hormone fragment released by a stretched, strained heart.
H High can mean
Heart failure, kidney disease, atrial fibrillation, lung clots. In someone short of breath, heart failure becomes likely above 450 under age 50, 900 at 50–75 and 1800 over 75.
L Low can mean
Normal. Obesity lowers it.
Good to know< 125 is the usual outpatient cut-off that makes heart failure unlikely.
BNPBNP< 100pg/mL< 100ng/L
B-type natriuretic peptide, the active hormone the strained heart releases.
H High can mean
Heart failure, kidney disease, older age.
L Low can mean
Normal. Obesity lowers it.
Troponin T, high-sensitivityhs-TnTMen< 0.015Women< 0.010ng/mLMen< 15Women< 10ng/L
A heart muscle protein that leaks out when heart cells are damaged.
H High can mean
Heart attack, myocarditis, heart failure, kidney disease, after extreme endurance exercise.
L Low can mean
Normal.
Good to knowCut-offs depend on the assay and on sex. For high-sensitivity troponin I they are about < 20 ng/L in men and < 15 in women. A rise between two draws matters most.
Creatine kinaseCKMen39–308Women26–192U/LMen0.65–5.13Women0.43–3.20µkat/L
A muscle enzyme that leaks out when muscle is damaged.
H High can mean
Hard training (can reach thousands for days), injury, statin side effects, low thyroid, rhabdomyolysis.
L Low can mean
Low muscle mass.
Good to knowDo not train hard for 2–3 days before the test.
ConvertU/L × 0.0167 = µkat/L
Read on the siteRay Peat on exercise →
D-dimerD-DIMER< 500ng/mL FEU< 0.50mg/L FEU
A piece of a broken-down clot.
H High can mean
A clot in the legs or lungs, recent surgery, infection, pregnancy, cancer, older age.
L Low can mean
A normal value makes a clot unlikely.
Good to knowUnits differ between labs (FEU or DDU, ng/mL or mg/L). Check the unit before comparing. Many labs raise the cut-off with age above 50.
Prothrombin timePT11–13.5seconds11–13.5secondsSame in SI
How long the blood takes to clot through the outer (extrinsic) pathway.
H High can mean
Warfarin, low vitamin K, liver disease.
L Low can mean
Not meaningful.
Good to knowReported together with the INR.
UnitsThe same number and unit in US and SI reports
INRINR0.9–1.1ratio0.9–1.1ratioSame in SI
The prothrombin time adjusted so it reads the same in every lab.
H High can mean
Warfarin (target usually 2–3), low vitamin K, liver disease.
L Low can mean
Not meaningful.
UnitsThe same number and unit in US and SI reports
Partial thromboplastin timeaPTT25–35seconds25–35secondsSame in SI
How long the blood takes to clot through the inner (intrinsic) pathway.
H High can mean
Heparin, hemophilia, von Willebrand disease, lupus anticoagulant.
L Low can mean
Not meaningful.
UnitsThe same number and unit in US and SI reports
14 · IMM
Immune and autoimmune
Antibody levels and the screening tests for autoimmune and celiac disease.
Immunoglobulin GIgG800–1500mg/dL8.0–15.0g/L
The main antibody in the blood. Long-term immunity.
H High can mean
Chronic infection, autoimmune and liver disease, myeloma.
L Low can mean
Antibody deficiency, protein loss, steroid or immune drugs.
Convertmg/dL × 0.01 = g/L
Immunoglobulin AIgA90–325mg/dL0.9–3.3g/L
The antibody of the gut and airway linings.
H High can mean
Liver disease, chronic infection, IgA nephropathy.
L Low can mean
IgA deficiency (about 1 in 500 people). It makes the celiac tTG-IgA test falsely negative.
Convertmg/dL × 0.01 = g/L
Read on the siteGut health studies →
Immunoglobulin MIgM45–150mg/dL0.45–1.5g/L
The first antibody made in a new infection.
H High can mean
Recent infection, some liver and blood diseases.
L Low can mean
Antibody deficiency.
Convertmg/dL × 0.01 = g/L
Immunoglobulin E, totalIgE< 100IU/mL< 100kU/L
The allergy antibody.
H High can mean
Allergy, asthma, eczema, parasites.
L Low can mean
Normal.
Good to knowUpper limits differ widely between labs (about 100 to 380). Specific IgE tests show what you react to.
Antinuclear antibodiesANANegative (< 1:80)titerNegative (< 1:80)titerSame in SI
Antibodies against parts of your own cell nucleus. A screen for autoimmune disease.
H High can mean
Lupus, Sjögren's, scleroderma, autoimmune thyroid and liver disease. Low titers (1:40, 1:80) are common in healthy people.
L Low can mean
Normal.
Good to knowCut-offs vary from 1:40 to 1:160 between labs. A positive ANA alone is not a diagnosis.
UnitsThe same number and unit in US and SI reports
Rheumatoid factorRF< 14IU/mL< 14IU/mLSame in SI
An antibody linked to rheumatoid arthritis.
H High can mean
Rheumatoid arthritis, Sjögren's, chronic infection, older age.
L Low can mean
Normal.
Good to knowThe cut-off depends on the method (some labs use < 24). Anti-CCP antibodies are more specific for rheumatoid arthritis.
UnitsThe same number and unit in US and SI reports
Tissue transglutaminase IgAtTG-IgA< 4U/mL< 4U/mLSame in SI
The main blood test for celiac disease.
H High can mean
Celiac disease. Very high values (10 times the limit) are nearly diagnostic.
L Low can mean
Normal, but only if total IgA is normal and you were eating gluten.
Good to knowEat gluten daily for at least 6 weeks before the test. The cut-off and unit depend on the kit.
UnitsThe same number and unit in US and SI reports
Read on the siteHow to fix leaky gut →
15 · ONC
Tumor markers
These follow a known cancer over time. None is a good screening test on its own: many benign conditions raise them.
Carcinoembryonic antigenCEANon-smokers< 3.0Smokers< 5.0ng/mLNon-smokers< 3.0Smokers< 5.0µg/L
A protein used to follow colon and some other cancers.
H High can mean
Colon, lung, breast and other cancers, smoking, inflammatory bowel disease, liver disease.
L Low can mean
Normal.
CA-125CA-125< 35U/mL< 35kU/L
A protein used to follow ovarian cancer.
H High can mean
Ovarian cancer, endometriosis, menstruation, pregnancy, fibroids, liver disease.
L Low can mean
Normal.
CA 19-9CA 19-9< 37U/mL< 37kU/L
A marker used to follow pancreatic and bile duct cancer.
H High can mean
Pancreatic cancer, blocked bile ducts, pancreatitis.
L Low can mean
Normal. About 5–10% of people cannot make it at all.
Alpha-fetoproteinAFP< 10ng/mL< 10µg/L
A fetal protein used to follow liver cancer and testicular tumors.
H High can mean
Liver cancer, testicular cancer, hepatitis, pregnancy.
L Low can mean
Normal.
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How to read these numbers
- A reference range is the middle 95% of healthy people. So 1 healthy person in 20 lands outside it on any test, and a value inside it is not always ideal.
- Lipid and sugar numbers are targets set by guidelines, not population averages.
- US units are mass per volume (mg/dL, ng/mL). SI units count molecules (mmol/L, nmol/L). The conversion factor is in each open row.
- Timing matters. Draw hormones in the morning, fast for glucose, insulin and iron, skip hard training for 2 days, and stop biotin 2 days before thyroid and hormone tests.
- One result is a snapshot. Repeat anything surprising before acting on it.
Sources for the ranges
- ABIM: Laboratory test reference ranges (January 2026)
- Mayo Clinic Laboratories: test catalog reference values
- American Diabetes Association: Standards of Care, diagnosis of diabetes
- NCEP ATP III: cholesterol and triglyceride levels
- Travison 2017: harmonized reference ranges for testosterone in men
- Endocrine Society 2011: vitamin D deficiency guideline
- KDIGO 2024: chronic kidney disease guideline
- SI conversion factors: AMA Manual of Style