Exercise performance in children with severe beta-thalassemia before and after transfusion.

Unlabelled: Thalassemia major is associated with impaired exercise tolerance because of the severe anemia and cardiopulmonary dysfunction characteristic of the condition.
Objective: To assess the exercise performance in thalassemic children before and two hours after hemotransfusion.
Patients and Methods: The study included eleven children with thalassemia major (12.3 +/- 2.8 years; Hb g/dl = 8.1 +/- 1.3) and 11 matched controls. All subjects underwent comprehensive pulmonary function assessment and incremental exercise test on a treadmill.
Results: The thalassemic children were, in general, shorter and lighter than their healthy counterparts; we also found lower absolute values of lung function parameters which did not reach statistical significances. On the other hand the most considerable differences were found in diffusion capacity (uncorrected TL(L,CO) % = 56.8 +/- 12.1 vs. 94.3 +/- 16.1 in controls; p<0.001) and blood oxygen content (ctO2 mmol.L(-1) = 4.7 +/- 1.1 vs. 8.3 +/- 0.8, p<0.05). The thalassemic children had significantly lower exercise capacity compared to controls (VO2/ kg = 27.1 +/- 5.0 vs. 37.1 +/- 3.2 mL.min(-1).kg(-1); p<0.001). In the patients' group hemoglobin was elevated significantly two hours after transfusion (Hb g/L from 80.5 +/- 12.7 to 93.6 +/- 10.6; p<0.001) leading to significant improvement in exercise duration (7.3 +/- 2.8 vs. 10.3 +/- 2.3 min; p<0.05), VO2/kg (28.5 +/- 5.0 vs. 36.2 +/- 7.1 mL.min(-1).kg(-1); p<0.05), and transfer factor (4.27 +/- 1.40 vs. 5.41 +/- 1.08 mmol.min(-1).kPa(-1); p=0.003). There were strong correlations between Hb and TL(L,CO) and VO2 (r = 0.687 and 0.750, respectively; p < 0.01 for both).
Conclusions: Patients with thalassemia major have a seriously reduced transfer factor and exercise impairment. The short-term changes in hemoglobin concentration are associated with significant improvement in exercise performance.