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

Thalassemia major is associated with impaired exercise tolerance because of the severe anemia and cardiopulmonary dysfunction characteristic of the condition.

To assess the exercise performance in thalassemic children before and two hours after hemotransfusion.

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.

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).

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.