Postoperative changes in bone metabolism and bone mineral density in Japanese patients with acromegaly: a 3-year prospective study

Growth hormone and insulin-like growth factor-I play important roles in regulating bone metabolism and bone mineral density in adulthood. However, the effect of excess growth hormone on bone metabolism and bone mineral density is not fully understood. Here, we investigated the long-term changes in bone metabolism and bone mineral density after a rapid decline in growth hormone levels due to transsphenoidal surgery in acromegalic patients. Eighteen acromegalic patients (10 males and 8 females) who underwent transsphenoidal surgery were enrolled in this prospective study. Bone formation marker (serum bone alkaline phosphatase), bone resorption marker (urinary type I collagen cross-linked N-telopeptide), and bone mineral density were measured before surgery and at 3 months, 1 year, and 3 years after transsphenoidal surgery. While both serum bone alkaline phosphatase and urinary type I collagen cross-linked N-telopeptide levels decreased significantly after surgery, serum bone alkaline phosphatase/urinary type I collagen cross-linked N-telopeptide ratio was significantly increased at 3 months and 3 years after surgery. Bone mineral density did not change markedly after surgery. In conclusion, the rapid decline in growth hormone levels following transsphenoidal surgery had no marked effect on bone mineral density for up to 3 years, despite significant changes in levels of bone turnover makers post-surgery.