Differential diagnosis of anemias

1. Big picture

Anemia in children is not a final diagnosis; it is a sign. In the exam, the safest approach is:

Confirm anemia → assess severity and danger signs → classify by mean corpuscular volume (MCV) and reticulocyte count → look for iron deficiency, hemolysis, blood loss, marrow failure, chronic inflammation, renal disease, malignancy, or inherited disease.

The examiner wants to hear that you do not simply say “iron deficiency” in every pale child. You must first decide:

1. Is the child stable or acutely ill?
2. Is the anemia microcytic, normocytic, or macrocytic?
3. Is the bone marrow responding? Reticulocytes high = marrow is working → blood loss or hemolysis. Reticulocytes low = marrow is not producing → deficiency, inflammation, renal disease, marrow failure, leukemia.

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