Reference database of CrossLaps and osteocalcin for a healthy Iranian population

Markers of bone turnover are becoming an important tool for practitioners in the management of osteoporosis. Therefore, it is essential to establish a reference database of the markers before using them in various clinical settings. A total of 785 individuals (37% males, 63% females) without apparent or suggested abnormalities affecting bone mass were randomly selected from 13 clusters in Bushehr Port in southern Iran. The serum CrossLaps ELISA and the N-MID Osteocalcin ELISA were used for the quantitative measurement of CrossLaps and osteocalcin in sera. Bone mineral density was determined for the lumbar spines (L2-L4), proximal femur (neck), and forearm (the distal part) using dual-energy X-ray absorptiometry. Men had higher biochemical serum bone markers (P<0.0001). In women, there were progressive increases in serum CrossLaps after 30 years of age, peaking at >60 years. In men, serum CrossLaps levels were decreased progressively by increases in age, with the peak at 20 - 29 years. In women, there was a significant decrease in serum osteocalcin from 20 - 29 years to 30-49 years, followed by a progressive increases during 50 - 59 years, with the peak at >60 years. In men, the highest concentrations for serum osteocalcin occurred at 20 - 29 years. At all sites checked for bone mineral densitys, women in the high osteocalcin quartile had the lowest mean bone mineral densitys values, but women in the high CrossLaps quartile had the lowest mean bone mineral densitys at lumbar and radial sites. However, in men, bone mineral densitys values at neither site differed between the lowest and the highest quartiles of serum biochemical bone markers. We presented a five- year age-specific mean values of bone markers in a general healthy Iranian population. Only women in the high osteocalcin and CrossLaps quartiles had the lowest mean bone mineral densitys values at the lumbar and radial sites. Our results suggest that the significance of osteoclastic bone resorption or bone formation as a determinant of bone mineral densitys may depend on sex.