Ten Years of Growth Hormone (GH) Replacement Normalizes Muscle Strength in GH-Deficient Adults

Context: GH replacement for 1–5 yr improves, but does not fully normalize, muscle strength. Objective, Design, and Patients: In this single-center, open-labeled, prospective study, the effects of 10 yr of GH replacement on muscle strength and neuromuscular function were followed in 109 consecutive adults (61 men; mean age 50.0 yr; range 22–74 yr) with adult-onset GH deficiency. Results: The mean initial GH dose of 0.88 mg/d was gradually lowered to 0.47 mg/d. The mean IGF-I sd score increased from −1.54 at baseline to 1.12 at study end. GH replacement induced a sustained increase in lean mass and isometric knee flexor strength (60°). In most other measures of upper leg and handgrip strength, there were transient increases during the first half of the study (0–5 yr), whereas during the second half (5–10 yr), the absolute values of muscle strength decreased and returned to or even below the baseline values. However, after correction for age and gender using observed/predicted value ratios, there were sustai...