Microcytosis is typical in thalassemia. With a normal ferritin and hemoglobin concentration, I would start screening by measuring HPLC, HbA2 levels that are high in beta-thalassemia carriers. (HbA2 can be normal with “mild” thalassemia alleles and for several other reasons.) Microcytosis...

The "easy" part of microcytosis is that the differential diagnosis - TAILS - has remained the same for decades. However, there are some newer developments worth noting:T (Thalassemia) – Please see Dr. @Steinberg's answerA (Anemia of inflammation) - The “old” name, “anemi...

I wanted to add a few ideas - Thalassemia disease is an easy diagnosis. Its distinguishing Thal trait from IDA is more challenging: Don't ignore RBC count (!!). RBC > 6 is very good for thalassemia trait in the setting of microcytosis -  never see this in IDA. The Rule of 3's: RBC * 3 =...

Dr. @Bejjani's patient is likely to have HbS-Hereditary Persistence of Fetal Hemoglobin (HPFH) characterized by a large deletion that removes both the beta- and delta-globin genes. Microcytosis is usually present because the increased expression of the gamma-globin genes does not compensate totally ...

I will offer my anecdote n = 1 of a patient with mild microcytosis without anemia with normal iron studies, all as above, with aches/pains in his hips. Electrophoresis had Hb S of 63%, F 35%, and A2 2%, and subsequent XR/MRI showed extensive AVN of both hips. A simple electrophoresis was instrumenta...