Endocrine Abstracts

Growth hormone (GH) replacement in GH-deficient adults exerts clear effects on body composition, but there is a lack of high-quality evidence concerning its functional effects which may be clinically more important. This meta-analysis is carried out to determine the effects of GH replacement on exercise performance. A Medline search and examination of reference lists of included studies and relevant review articles identified 11 studies with utilizable, robust data, involving a total of 268 patients. All studies included were randomized, double-blind, placebo-controlled, and of either parallel or cross-over design. Information was retrieved in uniform format, with data pertaining to patient numbers, study design, GH dose, mean age, IGF-I levels, and exercise variables (VO₂ max, maximal power output, maximal heart rate) recorded. The data was analyzed using a fixed effects model, utilizing continuous data measured on different scales. A summary effect measure (d_s) was derived for the individual exercise parameters, while an overall summary effect was derived from the sum of all studies across different variables; 95% confidence intervals were calculated from the weighted variances of individual study effects. Results revealed significant improvement when all studies were combined (d_s =+0.32+0.24, P=0.012), and for those studies measuring maximal power output only (d_s=+0.4+0.34, P=0.012). Those utilising VO₂ max as the exercise parameter showed definite improvement but of borderline statistical significance (d_s=+0.34+0.27, P=0.07). No correlation was seen between mean age at diagnosis, initial IGF-1 levels or GH dose on the degree of benefit gained via any of the measured parameters. These results confirm the beneficial effect of GH replacement on exercise capacity in GH-deficient patients. This improvement in exercise capacity provides a further, more practical and compelling indication for treatment of patients with GH-deficiency.