The Change of Bone Turnover Markers and Bone Remodelling Balance in Acromegaly

Objectives: The aim of this study was to evaluate the change of bone metabolism and bone remodelling balance in active and biochemical controlled acromegalic patients. Methods: We recruited 68 consecutive patients diagnosed as acromegaly in Nanjing Drum Tower Hospital. Of those, 39 patients after treatments with complete follow-up data were included. 30 sex-, age- and BMI-matched healthy persons were also included as normal controls. Serum calcium, phosphorus, parathyroid hormone (PTH), 25-hydroxy-vitamin D, bone turnover markers [osteocalcin, C-terminal telopeptide of type 1 collagen (CTX) and procollagen type 1 N-terminal propeptide (P1NP)], and bone remodelling index were investigated at baseline and after treatment. Univariate and multivariate linear regression analysis was used to determine the independent predictors of bone turnover markers. Results: At baseline, acromegalic patients had higher serum calcium, phosphorus and lower PTH levels than controls (all P < 0.01). Acromegalic patients had higher serum osteocalcin [45.98(31.98, 60.27) vs 15.83(12.74, 19.96) ng/ml, P < 0.01], P1NP [115.50(72.64, 145.90) vs 36.45(30.45, 44.28) ng/ml, P < 0.01] and CTX than controls [1.12(0.79, 1.56) vs 0.37(0.30, 0.50) ng/ml, P < 0.01], and the bone remodelling index of acromegaly patients is significantly increase compared to healthy controls [4.27(1.31, 5.99) vs 0.03(-0.38, 0.63), P < 0.01]. Multivariate linear regression analysis revealed that serum insulin-like growth factor 1 (IGF-1) was an independent predictor for osteocalcin (r = 0.610, P = 0.000), P1NP (r = 0.601, P = 0.000) and CTX (r = 0.596, P = 0.000). After treatment, serum calcium and phosphorus decreased, while PTH increased in acromegalic patients. Serum levels of bone turnover markers osteocalcin, PINP, CTX and bone remodelling index were also significantly decreased after treatment (all P < 0.05). In patients with biochemical control after treatment, bone turnover markers and bone remodelling index almost decreased to normal level (all P > 0.05). Conclusion: Acromegalic patients exhibited PTH-independent calcium-phosphate alterations, enhanced bone turnover state and positive bone remodeling balance. The abnormal bone metabolism is reversible after biochemical control of acromegaly. [Key words]Acromegaly; Bone turnover markers; Bone remodelling index; Growth hormone; Insulin-like growth factor 1