The impact of glucocorticoid replacement on bone mineral density in patients with hypopituitarism before and after 2 years of growth hormone replacement therapy.

Abstract

Patients with hypopituitarism have reduced bone mineral density (BMD) and increased fracture risk. The aim of this study was to analyze the effects of glucocorticoid (GC) replacement on BMD before and after 2 years of GH therapy in hypopituitary patients. The main hypothesis was that patients on GC replacement demonstrate greater improvement in BMD when treated with GH. This was a post hoc analysis of data from a prospective single-center study. Data on 175 adult patients with hypopituitarism and verified GH deficiency due to nonfunctioning pituitary adenoma were analyzed. Ninety-eight (56%) were GC insufficient, receiving a mean ± SD hydrocortisone equivalent dose of 20.9 ± 5.0 mg/d. BMD before and after 2 years of GH replacement therapy was measured by using dual-energy X-ray absorptiometry. BMD at baseline did not differ between GC-sufficient and -insufficient patients, neither at lumbar spine nor femur neck. After 2 years on GH replacement, BMD increased in both groups. After adjustment for weight, age, gender, free T4 concentrations, change in IGF-I levels, and sex hormone treatment, GC sufficiency was associated with a greater increase in BMD at the femur neck (ΔT-score in GC insufficient patients 0.09 ± 0.46, in GC sufficient patients 0.19 ± 0.43; P < .05) but not at the lumbar spine. GH replacement therapy for 2 years increased BMD in hypopituitary patients. In contrast to our hypothesis, GC-insufficient patients receiving near physiological doses of hydrocortisone do not show a greater therapeutic response to GH therapy than their GC-sufficient counterparts.