Objective: To evaluate prospectively cardiac function in children with primary hypothyroidism before and after replacement therapy with L-thyroxine.
Design: Prospective clinical and laboratory cardiac evaluation of children with hypothyroidism before and after therapy.
Setting: Hospital based.
Subjects: 20 consecutive children aged 6 months - 14 years with primary hypothyroidism.
Methods: Assessment of cardiac status by clinical, radiological, ECG, echocardiography, M-mode and 2 dimensional echo-Doppler study and phonocardiography for systolic and diastolic functions and structural anomalies.
Results: Indices of myocardial contractility like ejection fraction (EF), velocity of circumferential fibre shortening (VCF) did not change with therapy. However, systolic time intervals, both left ventricular (before therapy 0.32+/-0.03 msec; after therapy 0.25+/-0.03 msec; p <0.001) showed a significant change. In diastolic functions, isovolumic relaxation time fell from 62+/-9 msec before therapy to 50+/-5 msec after therapy (p <0.001). Pericardial effusion was found in 10 children before treatment which disappeared in 7 following therapy.
Conclusion: Subtle evidence of alteration of myocardial function is thus seen in children with primary hypothyroidism which reverses with treatment.