Erythropoietin levels and microcytosis in heterozygous beta-thalassaemia.

Erythropoietin levels were determined in 50 Greek females: 20 beta-thalassaemia (beta-thal) heterozygotes, 15 with a diagnosis of iron-deficiency anaemia and 15 normal controls. In beta-thal trait carriers, the erythropoietin levels were slightly higher than in normal controls (16.65 +/- 4.43 vs. 12.84 +/- 2.47 mU/ml); these levels were significantly lower than those in iron-deficient subjects with the same degree of anaemia (55.24 +/- 31.35 mU/ml). In both groups, the erythropoietin levels are statistically correlated with the severity of anaemia (r = -0.537 p < 0.05 for iron deficiency; r = -0.610 p < 0.01 for beta-thal heterozygotes). In beta-thal heterozygotes, a close inverse correlation with red cell number and erythropoietin levels was also noted. It is suggested that microcytosis accompanying beta-thal trait constitutes an additional factor intervening in the regulation of erythropoiesis.