Cardiovascular effects of prolonged growth hormone replacement in adults

Abstract. Objectives . To study the cardiovascular effects of human growth hormone (GH) replacement therapy in adults. Intervention . Biosynthetic human GH given in a daily dose of 0.04 ± 0.01 IU kg^?1 for 6–18 months in an open trial. Patients . Thirty-four GH-deficient hypopituitary patients on conventional replacement therapy, aged 19–67 years and with a body mass index of 18.0–410.0 kg/m². Measurements . Resting blood pressure, exercise tolerance, renal function and routine blood counts were assessed every 6 months. Two-dimensional echocardiography and Doppler ultrasound scanning were performed at 0, 6 and 12 months of GH therapy. Results . Exercise time increased significantly on GH from 9.37 ± 2.64min at the start to 10.39 ± 2.86 min (P < 0.001), 10.90 ± 2.48 min (P < 0.001) and 11.11 ± 0.70 min (P < 0.001) at 6, 12 and 18 months respectively. There was no change in the heart rate or in the blood pressure at rest nor at the peak of exercise. No significant changes were observed in measures of cardiac structure (left ventricular mass index, left ventricular posterior wall thickness and interventricular septal thickness), ejection fraction nor in cardiac output. Isovolumic relaxation time, a marker of diastolic function, decreased in 24 patients after 6 months on GH (from 98.6 ± 15.9 to 89.6 ± 15.2 ms; P < 0.03) but it was not different from baseline in the 18 patients who were restudied at 12 months. There was no significant change in the left ventricular filling neither at 6 nor at 12 months. No significant changes were observed in plasma electrolytes, creatinine nor in blood count on GH treatment. Conclusions . Growth hormone replacement therapy in hypopituitary adults for 6–18 months produced sustained increase in exercise tolerance but was not associated with changes in cardiac structure or systolic function.