Not medically reviewed
Haematology
Haemoglobin (Hb)
Not medically reviewed · Content last updated · 1 min read ·
This is the date the draft was written, not a medical review date.
Haemoglobin is the oxygen-carrying protein of red cells and the primary measure used to define anaemia. Its concentration depends on age, sex, altitude, pregnancy and smoking.
Reference interval
| Conventional (g/dL) | SI (g/L) | |
|---|---|---|
| Men | 13.5–17.5 g/dL | 135–175 g/L |
| Women | 12–15.5 g/dL | 120–155 g/L |
Specimen: Whole blood (EDTA) · Conventional × 10 = SI
Causes of high values
Polycythaemia vera, secondary erythrocytosis (chronic hypoxia, smoking, high altitude, erythropoietin-secreting tumours), and haemoconcentration from dehydration.
Causes of low values
Anaemia: iron deficiency, chronic disease, vitamin B12 or folate deficiency, haemolysis, blood loss, marrow failure, haemoglobinopathies and chronic kidney disease. Haemodilution in pregnancy or fluid overload lowers values without red-cell mass loss.
Pre-analytical and method notes
Reference intervals vary by laboratory, analyser, age and population; WHO anaemia thresholds (2011) are about 13 g/dL in men, 12 g/dL in non-pregnant women and 11 g/dL in pregnancy. Altitude and smoking shift values upward; posture and venous stasis affect sampling.
References
- Rifai N, Horvath AR, Wittwer CT. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Elsevier, 6th edition (2018) — Tier 3 (textbook)
- Haemoglobin concentrations for the diagnosis of anaemia and assessment of severity (WHO/NMH/NHD/MNM/11.1). World Health Organization (2011) — Tier 1 (standards / international bodies)
- Loscalzo J, et al.. Harrison's Principles of Internal Medicine. McGraw-Hill, 21st edition (2022) — Tier 3 (textbook)
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