Anaemia
A drop in the haemoglobin level in the blood, reducing oxygen transport to tissues, most often caused by iron deficiency.
Anaemia is defined by low haemoglobin (<13 g/dL in men, <12 g/dL in women). Haemoglobin, a protein in red blood cells, carries oxygen. Less haemoglobin = less oxygen to the tissues = fatigue, breathlessness, pallor, palpitations, difficulty concentrating.
Main types:
- Iron-deficiency anaemia: the most common in the world
- Anaemia from B12 or folate (B9) deficiency: “macrocytic” anaemia
- Inflammatory, haemolytic and genetic anaemias (sickle cell disease, thalassaemia)
An original angle (deficiency BEFORE anaemia): iron-deficiency anaemia is the end stage of an iron deficiency. Long before haemoglobin falls, iron stores (ferritin) are silently depleted. You can therefore have “normal” haemoglobin but empty stores: this is “iron deficiency without anaemia”, which already causes fatigue, hair loss, restless legs and breathlessness.
Hence the importance of measuring ferritin, not just haemoglobin. Much unexplained tiredness (especially in women who menstruate) is iron deficiency masked by still-normal haemoglobin.
A diagnostic trap: ferritin is also a marker of inflammation. With inflammation, it can be falsely “normal” despite a deficiency. The result must be interpreted in context (CRP, transferrin saturation coefficient).
Never take iron supplements without testing: excess iron is toxic (pro-oxidant).