Increased serum levels of N-telopeptides (NTx) of bone collagen in postmenopausal Nigerian women

Serum levels of cross-linked N-telopeptides (NTx) of bone collagen, alkaline phosphatase (ALP), and intact parathyroid hormone (PTH) were determined in 64 premenopausal (PRM) and 86 postmenopausal (PSM) women living in northern Nigeria. Serum NTx values were correlated with ALP activity (r = 0.31-0.58, P < 0.01) and PTH (0.32-0.35, P < 0.01) in all of the subjects studied, and were also related to age (-0.47, P < 0.001) and body mass index (-0.45, P < 0.001) in PPM women. Menopause had the effect of increasing the circulating concentrations of NTx and ALP activity by 15% (P = 0.001) and 11% (P = 0.02), respectively; however, serum levels of PTH were not different between these two groups of women. Compared with Caucasian counterparts matched for age and body mass index, PSM Nigerian women had significantly increased circulating concentrations of NTx (21.7 versus 16.2 nmol BCE/liter, P = 0.01) and demonstrated a trend towards higher ALP activities and PTH levels. These results indicate that (1) discrete reference intervals should be defined for biochemical markers of bone metabolism in African populations, (2) Nigerian women have relatively higher rates of bone turnover, and (3) further investigation of the implications of increased serum NTx should be undertaken using physical methods such as dual X-ray absorptiometry (DXA) and bone ultrasound attenuation.