Iron · g/L

Hemoglobin

Hemoglobin is the protein in red blood cells that binds oxygen in the lungs and carries it through the body (and carries away carbon dioxide). It contains iron, which gives blood its red color. The measurement shows the blood's oxygen-carrying capacity.

See my Hemoglobin explained →

Ranges we useWHO

Rating	Range
Talk to a doctor	below 110 g/L
Worth improving	110 – 120 g/L
No rating	120 – 130 g/L
Good	130 g/L and above

This marker also has 2 age- or sex-specific range sets in the app — the table shows the general one.

Source: WHO · Guideline on haemoglobin cutoffs to define anaemia in individuals and populations · 2024 · open

Why it matters

WHO: a low level means anemia (fatigue, shortness of breath); the limits are sex-specific.

If it’s low

Low hemoglobin = anemia. The body receives less oxygen, which shows up as fatigue, breathlessness on exertion, pallor, sometimes dizziness or palpitations. It is essential to find the cause — not just raise the number.

If it’s high

High hemoglobin is rarer. It is often apparent (dehydration — the blood is concentrated) or a result of smoking, living at altitude, lung/heart disease; rarely true polycythemia.

What to do

Low hemoglobin should be clarified — first ferritin (iron stores) and MCV. Supplement iron only with confirmed deficiency. Markedly low or with symptoms → seek advice.