Muscle strength in elderly adults with GH deficiency after 10 years of GH replacement

Abstract

Only few studies have investigated the effects of GH replacement on muscle strength in elderly patients with GH deficiency (GHD). OBJECTIVE, DESIGN, AND PATIENTS: In this prospective open-labeled study, the effects of 10 years of GH replacement on muscle strength and neuromuscular function were followed in 24 elderly GHD adults (mean age of 65.2 years; range 61-74 years). Muscle strength was compared with reference values obtained from the background population. The mean initial GH dose of 0.72 mg/day was lowered to 0.37 mg/day. The mean IGF1 SDS increased from -1.10 at baseline to 1.17 at study end. GH replacement induced a sustained increase in lean body mass and a transient increase in isometric knee flexor strength. Isometric knee extensor strength was reduced after 10 years. However, after correction for age and gender, using observed/predicted value ratios, there was sustained and even progressive increase in most variables reflecting muscle strength. Measurements of neuromuscular function showed unchanged voluntary motor unit activation after 10 years. Ten years of GH replacement therapy in elderly GHD adults resulted in a transient increase in isometric knee flexor strength, and provided protection from most of the normal age-related decline in muscle performance and neuromuscular function.