Discontinuing Long-Term GH Replacement Therapy--A Randomized, Placebo-Controlled Crossover Trial in Adult GH Deficiency

Context: Adult GH deficiency (GHD) is associated with impaired quality of life (QoL) and increased cardiovascular risk. Continued long-term efficacy in terms of QoL and cardiovascular risk factors has been indicated in open surveillance studies. Objectives: The aim was to study the impact of discontinuation of long-term GH replacement on QoL, body composition, and metabolism. Design and Setting: We conducted a randomized, double-blind, placebo-controlled 4-month crossover trial in a referral center. Patients: Sixty adult hypopituitary patients with GHD and more than 3 yr of continuous GH replacement therapy (mean treatment duration, 10 yr) participated in the study. Intervention: Patients received GH or placebo. Main Outcome Measurements: We measured QoL using validated questionnaires; body composition using computer tomography, dual-energy x-ray absorptiometry, and bioelectrical impedance spectroscopy; and insulin sensitivity using the short insulin tolerance test. Results: Mean serum IGF-I decreased from 168 ± 52 to 98 ± 47 μg/liter during the placebo period (P < 0.001). Two QoL domains (emotional reactions and positive well-being) in the Nottingham Health Profile and Psychological General Well-Being questionnaires deteriorated during placebo, compared with GH treatment (P < 0.05). Waist circumference and sc and visceral fat mass increased, and extracellular water and muscle area decreased during the placebo period (all P < 0.05). C-reactive protein and total-, low-density lipoprotein-, and high-density lipoprotein-cholesterol increased, and insulin sensitivity improved during placebo, compared to GH treatment (P < 0.05). Conclusion: After more than 3 yr of GH replacement therapy, a 4-month period of placebo treatment caused self-perceived deterioration in QoL and increased abdominal fat accumulation. Moreover, markers of systemic inflammation and lipid status deteriorated, whereas insulin sensitivity improved. Long-term continuous GH replacement is needed to maintain therapeutic effects of GH on QoL and cardiovascular risk factors.