CARDIOVASCULAR EFFECTS OF GROWTH-HORMONE REPLACEMENT THERAPY IN HYPOPITUITARY ADULTS

In the present study the effects of replacement with biosynthetic huma n growth hormone (GH) in a large group of hypopituitary adults on card iac structure and function were investigated. Thirty-six GH-deficient, hypopituitary patients (17 males and 19 females; aged 19-67 years) on conventional replacement therapy without GH were studied. Twenty-nine of the patients had acquired hypopituitarism in adult life, mainly du e to pituitary tumours. The design of the study was a prospective, ran domized, double-blind placebo-controlled trial for 6 months. Growth ho rmone (17 patients) was given in a daily dose of 0.02-0.05 IU/kg body wt sc (or a placebo, 19 patients) according to the patients' tolerance . Other pituitary replacement treatment was unchanged. Resting and exe rcise electrocardiography using the Bruce protocol, two-dimensional ec hocardiography, Doppler ultrasound scanning and serum insulin-like gro wth factor I (TGF-I) were assessed at 0 and 6 months. Resting blood pr essure was measured at 0, 1, 3 and 6 months. Serum IGF-T increased sig nificantly on GH treatment (mean +/- so) GH: 293 +/- 197 vs placebo: 8 2 +/- 40 mu g/l; p < 0.0001 at 6 months). Exercise time increased sign ificantly on GH but not on placebo (GH: 8.45 +/- 3.16 to 9.38 +/- 2.42 min.sec, p < 0.01; placebo 9.08 +/- 4.35 to 9.50 +/- 4.14 min.sec, NS ), although the change was not significantly different between the two . There was no change in the heart rate or the blood pressure either a t rest or at the peak of exercise. No significant changes were observe d in the left ventricular mass index, the left ventricular posterior w all thickness, the interventricular septal thickness, the ejection fra ction or the cardiac output. Isovolumic relaxation time, a measure of the left ventricular diastolic function, decreased significantly on GH but not on placebo (GH: 98 +/- 18 to 89 +/- 11 ms, p = 0.03; placebo: 93 +/- 17 to 89 +/- 14 ms, NS), although again the change on GH was n ot significantly different from that on placebo. There was no signific ant change in the left ventricular filling. No significant changes wer e observed in plasma levels of urea, electrolytes or creatinine on eit her GH or placebo. In conclusion, six months of GH replacement therapy in hypopituitary adults had favourable cardiovascular effects, includ ing increased exercise tolerance and improved diastolic function,