Reference ranges for blood tests

A reference range is a set of values used by a health professional to interpret a set of test results. The range is usually defined as the set of values 95% of the normal population falls within.

It must be remembered that the reference range will vary, depending on the age, sex and race of a population, and even the machines the laboratory uses to do the tests. Also remember that by definition 5% of the normal population will fall outside the reference range.

These are approximate adult values that are intended as a guide to students and those interested, they are not a substitute for medical advice.

Clinical biochemistry

Electrolytes

Test	Range	Comments
Sodium (Na)	130 - 145 mmol/L
Potassium (K)	3.5 - 5.0 mmol/L
Urea
Creatinine	50 - 110 µmol/L

Liver function tests

Total Protein	60 - 80 g/L
Albumin	30 - 50 g/L
Total Bilirubin	2 - 14 µmol/L
Direct Bilirubin	0 - 4 µmol/L
Alanine transaminase (ALT)	8 - 40 U/L	Also called...
Alkaline phosphatase (ALP)	40 - 130 U/L	Higher in children and pregnant women.

Other enzymes

Creatine kinase (CK)
Amylase	25 - 125 U/L

Lipids

Triglycerides	0.4 - 2.0 mmol/L
Total cholesterol	3.0 - 5.5 mmol/L
HDL cholesterol (male)	0.7 - 1.9 mmol/L
(female)	0.9 - 2.4 mmol/L
LDL cholesterol	2.4 - 4.0 mmol/l	Not valid when triglycerides >5.0 mmol/L.

Haematology

Red blood cells

Haemoglobin (Hb) (male)	130 - 180 g/L	Higher in neonates, lower in children.
(female)	115 - 160 g/L	Sex difference negligible into adulthood.
Haematocrit (Hct) (male)	0.38 - 0.52
(female)	0.35 - 0.47
Mean cell volume (MCV)	80 - 98 fL
Mean cell haemoglobin (MCH)	26 - 34 pg
Red cell count (male)	4.5 - 6.5 x1012/L
(female)	3.8 - 5.8 x1012/L

White blood cells

Total white blood cells	4.0 - 11.0 x109/L	Higher in neonates and infants.
Neutrophils	2.0 - 7.5 x109/L
Lymphocytes	1.0 - 4.0 x109/L
Monocytes	0.0 - 0.8 x109/L
Eosinophils	0.0 - 0.5 x109/L
Basophils	0.0 - 0.2 x109/L