Aims/hypothesis: Bone turnover markers mainly reflect three processes: bone remodelling, linear growth, and bone modelling. These occur at different rates depending on age. Oestradiol levels, a mediator of all processes of bone turnover, vary according to sex and age whereas, parathyroid hormone levels, an important regulator of bone remodelling, vary with age. We hypothesised that gender and age differences in the bone formation marker, serum amino terminal propeptide of type 1 collagen (PINP) and the bone resorption marker, serum β carboxy (C) terminal telopeptide (βCTX), could be related to differences in these hormones.
Methods: We performed an observational, cross-sectional study in 180 participants, 90 men and 90 women, divided into three groups (30/group) by age: Group A 1618 years, Group B 3032 years and Groups C over 70 years. In all individuals we measured fasting serum oestradiol, parathyroid hormone, serum βCTX and PINP at 9am.
|Group A||Group B||Group C|
|Oestradiol (pg/ml)||21.0 (9)||68.3 (58)||22.9 (6)||88.8 (87)||24.3 (12)||8.4 (4)|
|PTH (pg/ml)||34.5 (12)||35.2 (15)||35.3 (12)||36.2 (10.1)||46.7 (20)||46.3 (28)|
|Serum βCTX (ng/ml)||1.3 (0.4)||0.7 (0.2)||0.5 (0.2)||0.3 (0.1)||0.4 (0.2)||0.5 (0.2)|
|PINP (ng/ml)||201.4 (101)||106.4 (41)||53.6 (23)||38.7 (17)||54.2 (80)||50.7 (20)|
Results: In Group A (1618 years) serum βCTX (P<0.001); PINP (P<0.001) and in Group B (3032 years) serum βCTX (P<0.001); PINP (P=0.003) were significantly higher in males compared to females whilst in the elderly Group C values were similar: serum βCTX (P=0.2) PINP (P=0.2). Using multiple linear regression age, sex and oestradiol were significant predictors for serum βCTX (P<0.001), (P=0.006) (P<0.001) and PINP (P<0.001), (P=0.03) and (P=0.02), respectively. PTH had no effect whilst oestradiol was a negative predictor for bone marker levels.
Conclusions/interpretation: Younger men were found to have higher bone turnover markers then women but levels were similar in the elderly. This study highlights the importance of having different bone turnover marker reference intervals for young men and women.