Diagnosis of beta-thalassaemia major in previously transfused patients

The study was conducted to evaluate the effects of blood transfusion(s) on the haematological picture of b-thalassaemia major.

Retrospective case control study.

Department of Haematology, Armed Forces Institute of Pathology, Rawalpindi from January 1999 to December 2000.

A total of 280 consecutive patients of beta-thalassaemia major were studied. They were diagnosed by haematological parameters, and Hb-F estimation. Parent's study and PCR was also used when required.

Out of the 280 patients 109 (39%) had received one or more blood transfusions (cases). The remaining 171 patients who did not receive any transfusion served as controls. The mean MCV, MCH and Hb-F in cases were significantly higher than in the controls (p<0.05). The mean Hb-F in 95 cases, which had received occasional ( <4) transfusions, was higher (33%) than in the 14 cases who had received >4 transfusions (17%) (p=0.016). In the occasionally transfused patients Hb-F level was directly related to the time since last transfusion. In 44/109 (40%) transfused patients (Hb-F >30%) the diagnosis of thalassaemia was not difficult. In 54/109 (50%) patients (Hb-F: 5-30%) the diagnosis was aided by parent's study, while PCR for thalassaemia mutations was required in 11/109 (10%) patients (Hb-F <5%).

In most transfused patients of thalassaemia major MCV and MCH were significantly higher while Hb-F was lower than in the un-transfused patients. There was a linear correlation between Hb-F level and time since last transfusion in the occasionally transfused patients. However, the reduction in Hb-F level was more marked and sustained in multipally transfused patients. Parent's study and PCR are useful aids in establishing the correct diagnosis in these patients.