Effects of Recombinant Human Growth Hormone (Somatropin 191aa) Replacement Therapy on Fat-Free Mass Density and Lipolytic Homeostasis in Growth Hormone-Deficient Adults

Journal Context: The New England Journal of Medicine | Identifiers: DOI: 10.1056/NEJM198910263211703 / PMID: 2797101

Principal Investigators: Salomon, F., Cuneo, R. C., Hesp, R., & Sönksen, P. H. (Department of Endocrinology, St. Thomas's Hospital, London)

Methodology: A double-blind, placebo-controlled human trial enrolling 24 adults with severe growth hormone deficiency. Subjects were randomized to receive either a daily subcutaneous injection of recombinant Somatropin (191aa) or a placebo over a continuous 6-month timeline to evaluate total body fat-mass shifts and lean mass accretion via potassium-40 tracking.

Key Findings: 6 months of true 191aa Somatropin therapy induced a massive structural shift in body composition. The active treatment cohort experienced an average gain of $5.5\text{ kg}$ of pure lean fat-free mass, while concurrently executing an average loss of $5.7\text{ kg}$ of total fat mass. The study also documented a substantial drop in circulating low-density lipoprotein (LDL) cholesterol and a profound improvement in systemic physical work capacity.