Objective: To determine whether growth hormone replacement in older men improves functional ability.
Design: Randomized, controlled, double-blind trial.
Setting: General community.
Patients: 52 healthy men older than 69 years of age with well-preserved functional ability but low baseline insulin-like growth factor 1 levels.
Intervention: Growth hormone (0.03 mg/kg of body weight) or placebo given three times a week for 6 months.
Measurements: Body composition, knee and hand grip muscle strength, systemic endurance, and cognitive function.
Results: The participants' mean age was 75.0 years (range, 70 to 85 years). At 6 months, lean mass had increased on average by 4.3% in the growth hormone group and had decreased by 0.1% in the placebo group, a difference of 4.4 percentage points (95% CI, 2.1 to 6.8 percentage points). Fat mass decreased by an average of 13.1% in the growth hormone group and by 0.3% in the placebo group, a difference of 12.8 percentage points (CI, 8.6 to 17.0 percentage points). No statistically or clinically significant differences were seen between the groups in knee or hand grip strength or in systemic endurance. The mean Trails B score in the growth hormone group improved by 8.5 seconds, whereas scores in the placebo group deteriorated by 5.0 seconds, a difference of 13.5 seconds (CI, 3.1 seconds to 23.9 seconds; P = 0.01) However, the growth hormone group's score on the Mini-Mental Status Examination deteriorated by 0.4, whereas the placebo group's score improved by 0.2, a difference of 0.6 (P = 0.11). The two treatment groups had almost identical scores on the Digit Symbol Substitution Test (P > 0.2). Twenty-six men in the growth hormone group had 48 incidents of side effects, and 26 placebo recipients had 14 incidents of side effects (P = 0.002). Dose reduction was required in 26% of the growth hormone recipients and in none of the placebo recipients (P < 0.001).
Conclusions: Physiologic doses of growth hormone given for 6 months to healthy older men with well-preserved functional abilities increased lean tissue mass and decreased fat mass. Although body composition improved with growth hormone use, functional ability did not improve. Side effects occurred frequently.