Lab tests
Lab tests, explained in plain words
What each test measures, the normal range, what a high or low result can mean, and when it's worth seeing a doctor.
CBC
CBC test: full form, normal ranges and what your blood count means
CBC stands for complete blood count. It measures your red blood cells and haemoglobin (which carry oxygen), white blood cells (which fight infection) and platelets (which help blood clot). Typical adult ranges are haemoglobin 13.5 to 17.5 g/dL in men and 12.0 to 15.5 in women, white cells 4,000 to 11,000 per µL, and platelets 150,000 to 450,000 per µL.
Read the guide
HbA1c
HbA1c test: normal range, chart and what your result means
A normal HbA1c is below 5.7% (39 mmol/mol). 5.7% to 6.4% (39 to 47 mmol/mol) is the prediabetes range, and 6.5% (48 mmol/mol) or higher is in the diabetes range, which a doctor confirms with a second test. HbA1c shows your average blood sugar over about three months, and you don't need to fast for it.
Read the guide
Lipid profile
Lipid profile test: normal cholesterol, HDL, LDL and triglyceride levels
For most adults, desirable levels are total cholesterol below 200 mg/dL (5.2 mmol/L), LDL ("bad") cholesterol below 100 mg/dL (2.6 mmol/L), HDL ("good") cholesterol of 40 mg/dL or more in men and 50 or more in women, and triglycerides below 150 mg/dL (1.7 mmol/L). People with diabetes or heart disease are usually given lower LDL targets.
Read the guide
TSH
TSH test: normal range, full form and what high or low TSH means
A normal TSH (thyroid-stimulating hormone) for most adults is about 0.4 to 4.0 mIU/L, though labs differ slightly. A higher TSH usually means an underactive thyroid, because the brain is pushing a slow thyroid harder; a lower TSH usually means an overactive one. Doctors read it with free T4, and ranges differ in pregnancy and older age.
Read the guide
Vitamin D
Vitamin D test: normal levels, deficiency symptoms and where to get it
Vitamin D is measured as 25-hydroxyvitamin D. Below 20 ng/mL (50 nmol/L) is deficient and below 12 ng/mL (30 nmol/L) is severely low. Most experts consider 20 ng/mL or more enough for bone health, and many labs print 30 to 100 ng/mL as the reference range. Above about 50 ng/mL brings no extra benefit, and very high levels can be harmful.
Read the guide
Creatinine
Creatinine test: normal range, high levels and what your result means
A normal serum creatinine is roughly 0.7 to 1.3 mg/dL (62 to 115 µmol/L) for adult men and 0.6 to 1.1 mg/dL (53 to 97 µmol/L) for adult women, though each lab prints its own range. Creatinine is a waste product your kidneys filter out, so a higher number can mean they're filtering less. Doctors read it with your eGFR.
Read the guide
Ferritin
Ferritin test: normal levels, low and high ferritin, and what your result means
A typical adult ferritin range is about 24 to 336 ng/mL for men and 11 to 307 ng/mL for women, though labs differ. Below 15 ng/mL means your iron stores are used up, and 15 to 30 is often low enough to cause symptoms. Ferritin also rises with inflammation, so doctors read it alongside your haemoglobin and iron tests.
Read the guide
