Exercise capacity in patients with beta-thalassaemia intermedia.

ABSTRACT

Thalassaemia intermedia patients can suffer fatigue and exercise capacity reduction, possibly because of anaemia, deconditioning and lack of exercise-induced haemoconcentration. We studied 21 beta-thalassaemia intermedia patients, 10 splenectomised (group A) and 11 not splenectomised (group B). Patients were evaluated by cardiopulmonary exercise test with blood sampling for haemoglobin and plasma protein measurements at rest and peak. During exercise, an isolated increase of haemoglobin suggested spleen contraction while a parallel increase of haemoglobin and proteins suggested fluid filtration through capillary wall. Groups were homogeneous for age and gender. Peak oxygen consumption (VO2) was 22.5 +/- 4.4 ml/min/kg (51 +/- 14%) and 24.3 +/- 7.0 (53 +/- 12%) in groups A and B respectively [not significant (NS)]. At rest, haemoglobin was 8.8 g/dl in both groups. Exercise-induced increment was 0.4 +/- 0.2 and 1.0 +/- 0.4 g/dl (P < 0.001) for haemoglobin and 4.0 +/- 3.0 and 5.0 +/- 4.0 g/l (NS) for proteins, in groups A and B respectively. Anaemia was the major cause of peak VO2 reduction (1097 +/- 260 ml/min). However, anaemia did not explain the entire exercise capacity reduction, suggesting the presence of muscular deconditioning. Exercise capacity is reduced in beta-thalassaemia intermedia because of anaemia and muscular deconditioning. Spleen contraction does not significantly influence exercise capacity although exercise-induced haemoconcentration was greater in patients with spleen.