Quantitative Evaluation of the Mechanisms of the Anaemia in Heterozygous β‐Thalassaemia

Ferrokinetic studies were carried out in 8 patients with heterozygous β-thalassaemia with anaemia of varying severity. Effective and ineffective erythropoiesis, mean red cell lifespan and non-erythroid iron turnover were estimated from the experimental data through a mathematical model of iron kinetics. Erythropoietic activity was markedly increased in all patients, but was variably ineffective (from 10 to 74%). A negative correlation (r = -0.855, P < 0.01) was found between the amount of ineffective erythropoiesis and Hb level. Red cell lifespan was variably shortened and there was a negative correlation between the degree of daily peripheral haemolysis and Hb level (r = -0.733, P < 0.05). Non-erythroid iron turnover was increased in most patients. The results provide quantitative measurements of the mechanisms responsible for the wide variation of the Hb level in heterozygous β-thalassaemia. Ineffective erythropoiesis seems to be the major reason for the anaemia. Peripheral haemolysis contributes to it, especially in the most severely affected patients. The increased non-erythroid iron turnover may be responsible for the pathology which characterizes heterozygotes in the adult life.