ELDERLY PATIENTS WITH ADULT-ONSET GROWTH-HORMONE DEFICIENCY ARE NOT OSTEOPENIC

The age-related decline in GH secretion has been implicated in the dev elopment of osteoporosis. GH-deficient adults show a significant reduc tion in bone mineral density (BMD), which is greater in those with chi ldhood-onset GH deficiency than in those with GH deficiency occurring in adult life. To determine whether GH deficiency in late adult life c auses a reduction in BMD beyond the decline observed with increasing a ge, we studied 21 patients over the age of 60 yr with GH deficiency ca used by organic pituitary disease and 23 controls of similar age and s ex distribution and BMI. Dual energy x-ray absorptiometry was used to determine total bone mass and BMD at the hip and in the lumbar spine. Serum osteocalcin was determined in all subjects and urinary deoxypyri dinoline/creatinine ratio in 19 patients and 21 controls. The median ( range) known duration of GH deficiency in the patients was 8 yr (range , 4-41 yr). The median (range) total bone mass was 2774 g (range, 1534 -3734) in the patients and 2717 g (range, 1235-3549) in the controls ( P = 0.42). Specific measurements of BMD made at L2-L4, the right femor al neck, the right femoral trochanter, and Ward's triangle were 1.234 (range, 0.778-1.507) vs. 1.144 g/cm(2) (range, 0.809-1.466; P = 0.48), 0.921 (range, 0.605-1.372) vs. 0.96 g/cm(2) (range, 0.534-1.315; P = 0.62), 0.92 (range, 0.523-1.229) vs. 0.915 g/cm(2) (range, 0.353-1.313 ; P = 0.68), and 0.773 (range, 0.408-1.289) us. 0.806 g/cm(2) (range, 0.359-1.154; P = 0.81) in the patients and controls, respectively. The median (range) serum osteocalcin was 11.5 (range, 3.6-23.0) vs. 15.1 ng/mL (range, 0.7-40.5, P = 0.019) in the patients and controls, respe ctively. The median (range) deoxypyridinoline crosslinks/creatinine ra tio was 3.5 mu mol/mol (range, 0.8-8.3) in the patients and 4.9 mu mol /mol (range, 3.0-9.7) in the controls (P 0.038). There was a significa nt correlation between serum insulin-like growth factor I and total bo ne mass in the controls, but not in the patients. These data demonstra te that BMD is not significantly altered in GH-deficient adults over t he age of 60 yr. Markers of bone formation and resorption are decrease d, however, suggesting that bone turnover is reduced. Further studies are required to determine whether the reduction in bone turnover in th ese patients is of benefit.