Elderly patients with adult-onset growth hormone deficiency are not osteopenic.

Abstract

The age-related decline in GH secretion has been implicated in the development of osteoporosis. GH-deficient adults show a significant reduction in bone mineral density (BMD), which is greater in those with childhood-onset GH deficiency than in those with GH deficiency occurring in adult life. To determine whether GH deficiency in late adult life causes a reduction in BMD beyond the decline observed with increasing age, we studied 21 patients over the age of 60 yr with GH deficiency caused by organic pituitary disease and 23 controls of similar age and sex 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 deoxypyridinoline/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 femoral neck, the right femoral trochanter, and Ward's triangle were 1.234 (range, 0.778-1.507) vs. 1.144 g/cm2 (range, 0.809-1.466; P = 0.48), 0.921 (range, 0.605-1.372) vs. 0.96 g/cm2 (range, 0.534-1.315; P = 0.62), 0.92 (range, 0.523-1.229) vs. 0.915 g/cm2 (range, 0.353-1.313; P = 0.68), and 0.773 (range, 0.408-1.289) vs. 0.806 g/cm2 (range, 0.353-1.154; 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, respectively. The median (range) deoxypyridinoline cross-links/creatinine ratio was 3.5 micromol/mol (range, 0.8-8.3) in the patients and 4.9 micromol/mol (range, 3.0-9.7) in the controls (P 0.038). There was a significant correlation between serum insulin-like growth factor I and total bone mass in the controls, but not in the patients. These data demonstrate that BMD is not significantly altered in GH-deficient adults over the age of 60 yr. Markers of bone formation and resorption are decreased, however, suggesting that bone turnover is reduced. Further studies are required to determine whether the reduction in bone turnover in these patients is of benefit.