Objective: We aimed to study the effect of biosynthetic growth hormone (GH) replacement in growth hormone deficient adults.
Design: We performed a double-blind placebo-controlled cross-over study of 6 months biosynthetic GH, replacement and 6 months placebo separated by a 1-month's washout period.
Patients: Fourteen growth hormone deficient adults were studied.
Measurements: We measured total body weight, percentage fat mass, lean body mass, muscle volume, exercise capacity, maximum oxygen consumption, muscle strength, bone mineral content, a number of biochemical parameters, IGF-I, GH antibodies and psychological well-being.
Results: Total body weight remained unchanged, but lean body mass increased (before GH mean +/- SEM 49.8 +/- 5.5, after 53.4 +/- 5.6 kg; placebo before 51.2 +/- 5.4, after 50.4 +/- 5.1 kg; P less than 0.05 and fat mass decreased (before GH 21.5 +/- 4.1, after 19.3 +/- 4.3; placebo before 19.3 +/- 4.0, after 22.5 +/- 4.5 kg; P less than 0.05). Thigh muscle volume increased: (before GH 94.1 +/- 7.7, after 99.5 +/- 8.4 ml; placebo before 99.3 +/- 8.6, after 95.4 +/- 7.8 ml/0.8 mm computerized tomographic slice; P less than 0.05). Exercise capacity increased (before GH 174 +/- 15, after 199 +/- 18.9 watts; placebo before 162.5 +/- 2.3, after 154 +/- 19.8 watts; P less than 0.05), as did maximum oxygen consumption (before GH 1.93 +/- 0.2, after 2.17 +/- 0.2 l/m; placebo before 1.92 +/- 0.3, after 1.98 +/- 0.2 l/m; P less than 0.05). There was no change in quadriceps muscle strength. Alkaline phosphatase increased (before GH 87.5 (32-158), after 106.0 (49-179) U/I, placebo 99.5 (50-145), after 72.0 (40-111) U/I; P less than 0.05) without a change in the spinal bone density. IGF-I increased (before GH 62 (36-97), after 216 (62-362) micrograms/l; placebo before 59 (52-112), after 60.5 (38-94) micrograms/l; P less than 0.05). Carbohydrate tolerance remained unchanged as did fasting lipids, serum sodium, potassium, urea, calcium, phosphate and liver transaminases. Psychological well-being remained unchanged. No growth hormone antibodies were detected before or after GH treatment.
Conclusions: GH alters the body composition of growth hormone deficient adults and leads to improved exercise capacity; alkaline phosphatase activity increases but without a change in spinal bone density, and carbohydrate tolerance remains unaltered.