High bone turnover is associated with low bone mass and spinal fracture in postmenopausal women.

Calcified tissue international

PubMedID: 9069162

Ravn P, Rix M, Andreassen H, Clemmesen B, Bidstrup M, Gunnes M. High bone turnover is associated with low bone mass and spinal fracture in postmenopausal women. Calcif Tissue Int. 1997;60(3):255-60.
A group of 366 healthy, white postmenopausal women, aged 50-81 years, mean age 66 years, were selected from the screened population of Scandinavians who were part of a multicenter study of the efficacy of tiludronate, a new bisphosphonate, in established postmenopausal osteoporosis. Eighty-eight women had a lumbar spine bone mineral density (BMD) above 0.860 g/cm2, and 278 women had a BMD below 0.860 g/cm2. Spinal fracture was diagnosed from lateral spine X-ray studies and defined as at least 20% height reduction (wedge, compression, or endplate fracture) in at least one vertebra (T4-L4). Bone resorption was assessed by measurement of the urinary excretion of type I collagen degradation products by the CrossLaps enzyme-linked immunoassay (ELISA). Bone formation was assessed by ELISA measurement of the N-terminal-midfragment as well as the intact serum osteocalcin (OCN-MID), thus omitting the influence of the instability of osteocalcin caused by the labile 6 amino acid C-terminal sequence. The women were divided into groups with high or low bone turnover according to the concentrations of urinary Cross-Laps or OCN-MID. Women in the quartiles with the highest concentrations of CrossLaps [519 +/- 119 micrograms/mmol (SD)] or OCN-MID [44.6 +/- 7.5 ng/ml (SD)] had 10-16% lower spinal BMD compared with women in the lowest quartiles (CrossLaps 170 +/- 48 micrograms/mmol (SD), and OCN-MID [22.1 +/- 3.0 ng/ml (SD)] (P < 0.0004). The prevalences of spinal fracture were 25 to 29% in the lowest quartiles, whereas the prevalences in the highest quartiles were almost double-53-54% (P < 0.006). If the women were subgrouped according to spinal BMD and prevalence of spinal fracture, corresponding results were found. Women with a BMD less than 0.860 g/cm2, without or with spinal fracture (n = 136 and n = 142), had 36-43% higher concentration of Cross-Laps (P = 0.0001) and 11-15% higher concentration of OCN-MID (P < 0.02), as compared with women with a BMD above 0.860 g/cm2 and no spinal fracture (n = 84). In conclusion, the results indicate a strong association among high bone turnover, low bone mass, and prevalence of spinal fracture, which supports the theory that high bone turnover is a risk factor for spinal fracture and osteoporosis.