Diagnosis of B-thalassaemia major in previously transfused patients

ABSTRACT

The study was conducted to evaluate the effects of blood transfusion[s] on the haematological picture of b-thalassaemia major. Design: Retrospective case control study. Place and Duration of Study Department of Haematology, Armed Forces Institute of Pathology, Rawalpindi from January1999 to December 2000. Subjects and A total of 280 consecutive patients of b-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