CARDIOVASCULAR EFFECTS OF PROLONGED GROWTH-HORMONE REPLACEMENT IN ADULTS

Objectives. To study the cardiovascular effects of human growth hormon e (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 i n an open trial. Patients. Thirty-four GH-deficient hypopituitary pati ents on conventional replacement therapy, aged 19-67 years and with a body mass index of 18.0-410.0 kg/m(2). Measurements. Resting blood pre ssure, exercise tolerance, renal function and routine blood counts wer e assessed every 6 months. Two-dimensional echocardiography and Dopple r ultrasound scanning were performed at 0, 6 and 12 months of GH thera py. Results. Exercise time increased significantly on GH from 9.37 +/- 2.64 min 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 b lood pressure at rest nor at the peak of exercise, No significant chan ges were observed in measures of cardiac structure (left ventricular m ass index, left ventricular posterior wall thickness and interventricu lar septal thickness), ejection fraction nor in cardiac output. Isovol umic 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 w ho were restudied at 12 months. There was no significant change in the left ventricular filling neither at 6 nor at 12 months. No significan t changes were observed in plasma electrolytes, creatinine nor in bloo d count on GH treatment. Conclusions. Growth hormone replacement thera py 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.