Haemoglobin cutoffs to define anaemia in individuals and populations
📌 Children
- 6 – 23 months: Hb <10.5 g/dL
- 24–59 months: <11.0 g/dL
- 5 – 11 years: <11.5 g/dL
- 12–14 years, nonpregnant girls: <12.0 g/dL
- 12–14 years, boys: <12.0 g/dL
📌 Adults
- 15–65 years, nonpregnant women: <12.0 g/dL
- 15–65 years, men: <13.0 g/dL
📌 Pregnancy
- First trimester: <11.0 g/dL
- Second trimester: <10.5 g/dL
- Third trimester: <11.0 g/dL
Haemoglobin cutoffs for severity of anaemia
Population | Normal (g/dL) | Mild anaemia (g/dL) | Moderate anaemia (g/dL) | Severe anaemia (g/dL) |
Children | ||||
6 – 23 months | ≥10.5 | 9.5–10.4 | 7.0–9.4 | <7.0 |
24–59 months | ≥11.0 | 10.0–10.9 | 7.0–9.9 | <7.0 |
5–11 years | ≥11.5 | 11.0–11.4 | 8.0–10.9 | <8.0 |
12–14 years, non-pregnant girls | ≥12.0 | 11.0–11.9 | 8.0–10.9 | <8.0 |
12–14 years, boys | ≥12.0 | 11.0–11.9 | 8.0–10.9 | <8.0 |
Adults | ||||
15–65 years, non-pregnant women | ≥12.0 | 11.0–11.9 | 8.0–10.9 | <8.0 |
15–65 years, men | ≥13.0 | 11.0–12.9 | 8.0–10.9 | <8.0 |
Pregnant | ||||
First trimester | ≥11.0 | 10.0–10.9 | 7.0–9.9 | <7.0 |
Second trimester | ≥10.5 | 9.5–10.4 | 7.0–9.4 | <7.0 |
Third trimester | ≥11.0 | 10.0–10.9 | 7.0–9.9 | <7.0 |
Haemodilution in pregnancy
- Maternal physiological adaptation to pregnancy: plasma volume expansion exceeds the increase in red blood cell mass, resulting in functional hemodilution. There is a drop in the concentration of red blood cells, hemoglobin, and hematocrit.
- Hemodilution is most pronounced during second trimester. Hence, WHO sets a lower hemoglobin threshold for second trimester compared to the first and third.
- In third trimester, plasma volume continues to increase, but at a slower rate. The discrepancy between plasma and RBC mass narrows, and hemoglobin levels stabilize
Reference
- WHO Guideline on haemoglobin cutoffs to define anaemia in individuals and populations https://www.who.int/publications/i/item/9789240088542
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