Blood work
What each marker measures and the range this site treats as healthy. Your lab's printed range and your doctor's judgement come first; ranges differ slightly between labs, and one result is a snapshot, not a sentence.
A sensible first panel to ask for: fasting glucose, HbA1c, a lipid panel, a comprehensive metabolic panel (kidney and liver), a complete blood count, TSH and vitamin D. Fast for 8 to 12 hours beforehand, with water only.
Blood sugar
| Marker | Healthy range | What it tells you |
|---|---|---|
| Fasting glucose | 70 to 99 mg/dL | Sugar in your blood after at least 8 hours without food. 100 to 125 mg/dL is the prediabetes range and 126 or higher, confirmed on a second test, is the diabetes range.
Sources: American Diabetes Association Professional Practice Committee Diabetes Care 2024 |
| Hemoglobin A1c | under 5.7 % | Your average blood sugar over roughly three months. 5.7 to 6.4% is the prediabetes range; 6.5% or higher is the diabetes range.
Sources: American Diabetes Association Professional Practice Committee Diabetes Care 2024 |
| Fasting insulin | under 15 µIU/mL | How hard your pancreas is working to keep blood sugar normal. A high fasting insulin with normal glucose is an early sign of insulin resistance.
Sources: Matthews DR et al. Diabetologia 1985 |
| HOMA-IR (calculated) | under 2 | Fasting glucose × fasting insulin ÷ 405. A simple estimate of insulin resistance. Cut-offs vary by population, so read it as a direction, not a diagnosis.
Sources: Matthews DR et al. Diabetologia 1985 |
Heart
| Marker | Healthy range | What it tells you |
|---|---|---|
| Total cholesterol | under 200 mg/dL | All the cholesterol in your blood. On its own it says little; LDL, HDL, triglycerides and ApoB say more.
Sources: Grundy SM et al. Circulation 2019 |
| LDL cholesterol | under 100 mg/dL | The cholesterol carried in particles that build plaque in artery walls. Lower over a lifetime means less heart disease. 190 or higher often runs in families and should be reviewed with a doctor.
Sources: Grundy SM et al. Circulation 2019 |
| HDL cholesterol | Men 40 or higher Women 50 or higher mg/dL |
Low HDL usually travels with high triglycerides, extra weight around the middle, and inactivity. Movement and losing waist size raise it; pills that raise it have not prevented heart attacks.
Sources: Grundy SM et al. Circulation 2019 |
| Triglycerides | under 150 mg/dL | Fat in the blood. It rises with sugar, refined starch, alcohol and excess calories, and responds quickly to changes in food and movement. 500 or higher carries a risk of pancreatitis.
Sources: Grundy SM et al. Circulation 2019; Skulas-Ray AC et al. Circulation 2019 |
| Non-HDL cholesterol | under 130 mg/dL | Total cholesterol minus HDL: all the plaque-forming cholesterol in one number.
Sources: Grundy SM et al. Circulation 2019 |
| Apolipoprotein B | under 90 mg/dL | A count of the plaque-forming particles themselves, and a more accurate guide to risk than LDL when the two disagree.
|
| Lipoprotein(a) | under 75 nmol/L | An inherited particle that raises heart risk. Food and exercise barely move it, so a high result is a reason to keep every other risk factor low and to tell your doctor and close family.
Sources: Kronenberg F et al. Eur Heart J 2022 |
Inflammation
| Marker | Healthy range | What it tells you |
|---|---|---|
| hs-CRP | under 1 mg/L | A marker of inflammation. Under 1 mg/L is low cardiovascular risk and over 3 is higher. Above 10 usually means a recent infection or injury, so repeat the test when you are well.
Sources: Ridker PM et al. N Engl J Med 2002 |
| Homocysteine | under 10 µmol/L | Rises when folate, B12 or B6 are low and with reduced kidney function. |
Nutrients
| Marker | Healthy range | What it tells you |
|---|---|---|
| Vitamin D (25-OH) | 30 to 100 ng/mL | Made in skin from sunlight and needed for bone and muscle. Under 20 ng/mL is deficient by Endocrine Society criteria.
Sources: Holick MF et al. J Clin Endocrinol Metab 2011; Manson JE et al. N Engl J Med 2019 |
| Vitamin B12 | 300 or higher pg/mL | Needed for nerves and red blood cells. Found only in animal foods. Low levels are common with age, metformin, acid-reducing medicine and vegan diets.
Sources: Stabler SP N Engl J Med 2013; Aroda VR et al. J Clin Endocrinol Metab 2016 |
| Folate | 4 or higher ng/mL | A B vitamin from leafy greens and legumes, needed to make new cells. |
| Ferritin | Men 30 to 300 Women 30 to 200 ng/mL |
Your iron stores. Low ferritin is the earliest sign of iron deficiency. Ferritin also rises with inflammation, liver disease and iron overload, so a high result needs a doctor's review, not less iron by guesswork.
Sources: Camaschella C N Engl J Med 2015 |
| Magnesium | 1.7 to 2.4 mg/dL | A mineral from greens, beans, nuts and whole grains. Blood levels fall only when stores are quite low. |
Blood count
| Marker | Healthy range | What it tells you |
|---|---|---|
| Hemoglobin | Men 13 to 17.5 Women 12 to 16 g/dL |
The oxygen-carrying protein in red blood cells. Low hemoglobin is anemia, and the cause should be found. |
| MCV | 80 to 100 fL | Average red blood cell size. Small cells point toward iron deficiency; large cells toward low B12 or folate. |
| White blood cells | 4 to 11 K/µL | Infection-fighting cells. Mild shifts are common with illness; persistent ones deserve a look. |
| Platelets | 150 to 400 K/µL | Cells that help blood clot. |
Thyroid
| Marker | Healthy range | What it tells you |
|---|---|---|
| TSH | 0.4 to 4.5 mIU/L | The signal your brain sends to your thyroid. High TSH suggests an underactive thyroid, low TSH an overactive one. Thyroid problems are treated with medicine, not diet. |
| Free T4 | 0.8 to 1.8 ng/dL | The main thyroid hormone circulating in your blood. |
Liver
| Marker | Healthy range | What it tells you |
|---|---|---|
| ALT | Men under 41 Women under 34 U/L |
A liver enzyme. The most common reason for a mildly high ALT is fat stored in the liver, which improves with weight loss, less sugar and alcohol, and exercise.
|
| AST | under 41 U/L | An enzyme from liver and muscle. Hard training in the days before a test can raise it. |
| GGT | Men under 61 Women under 41 U/L |
A liver enzyme that is sensitive to alcohol and to fat in the liver. |
| Albumin | 3.5 to 5.1 g/dL | The main protein made by your liver. |
Kidney
| Marker | Healthy range | What it tells you |
|---|---|---|
| Creatinine | Men 0.7 to 1.3 Women 0.6 to 1.1 mg/dL |
A waste product of muscle, cleared by the kidneys. More muscle and creatine supplements raise it a little. |
| eGFR | 90 or higher mL/min/1.73m² | How well your kidneys filter, estimated from creatinine, age and sex. Below 60 for three months or more is chronic kidney disease.
Sources: Inker LA et al. N Engl J Med 2021 |
| BUN | 6 to 24 mg/dL | A waste product of protein. Dehydration and a high-protein diet raise it. |
| Uric acid | Men under 7 Women under 6 mg/dL |
High uric acid goes with gout, sugary drinks, alcohol (beer most of all) and insulin resistance. |
| Sodium | 135 to 145 mmol/L | A blood salt governed mostly by water balance and hormones, not by how much salt you eat. |
| Potassium | 3.5 to 5.2 mmol/L | Critical for heart rhythm. Blood pressure pills and kidney function both affect it. |
| Calcium | 8.6 to 10.4 mg/dL | Blood calcium is tightly controlled by hormones. An abnormal result is about those hormones, not dairy. |
Hormones
| Marker | Healthy range | What it tells you |
|---|---|---|
| Total testosterone | Men 300 to 1000 Women under 71 ng/dL |
In men, a morning level under 300 ng/dL on two tests, with symptoms, is low. Sleep loss, excess body fat and heavy drinking all lower it. |