For patients with microcytosis MCV 75-79 and normal Hb, low TIBC, and normal ferritin do you always rule out thalassemia?

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 without iro...

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. @Dr. First Last's answer

A (Anemia of inflammation) - The “old” name, “anemia of chronic disease”, i...

I wanted to add a few ideas -

Thalassemia disease is an easy diagnosis. Its distinguishing Thal trait from IDA is more challenging:

1. Don't ignore RBC count (!!). RBC > 6 is very good for thalassemia trait in the setting of microcytosis - never see this in IDA.
2. The Rule of 3's: RBC * 3 = Hg, Hg * 3 =...

Dr. @Dr. First Last'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 t...

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...