Age-related trends and reference intervals of cross-linked C-telopeptide of type I collagen and procollagen type I N-propeptide from a reference population of Sri Lankan adult women

Abstract

Summary Reference values of bone turnover markers (BTMs) are determined by factors that are country-specific. In Sri Lanka, unavailability of BTM reference data has led to their non-use in management of osteoporosis. The results of this study can be used as reference data for women in Sri Lanka. Introduction This study was performed to establish age-related reference intervals for bone resorption marker; cross-linked C-telopeptide of type I collagen (CTX) and bone formation marker; procollagen type I N-propeptide (PINP) in a group of Sri Lankan adult women. Methods Adult women (n = 347) aged 20–70 years were recruited using age-stratified random sampling technique and categorized into age groups by decades. Serum CTX and PINP concentration were measured using enzyme-linked immunosorbent assay (ELISA). The geometric mean (95% confidence interval) and 2.5th and 97.5th percentiles were calculated. ANOVA was used to compare the means between groups. Results Mean CTX levels were relatively low and remained unchanged between 20 and 49 years. After the age of 49 years, mean CTXconcentration elevated significantly until the age of 70 years (43%, p < 0.001). Mean PINP concentrations were not significantly different between age categories (p > 0.05). Reference intervals of CTX and PINP were based on 2.5th and 97.5th percentile values. Reference intervals of CTX for the age groups of 20–29, 30–39, 40–49, 50–59, and 60–70 years were 0.19–0.97 ng/mL, 0.18–0.95 ng/mL, 0.20–1.29 ng/mL, 0.17–2.20 ng/mL, and 0.17–2.85 ng/mL respectively. Reference intervals of PINP for the same age groups were 118–810 pg/mL, 119–772 pg/mL, 116–645 pg/mL, 108–684 pg/mL, and 108–715 pg/mL respectively. Conclusion In Sri Lanka, bone turnover markers are not used in evaluating patients mainly due to lack of normative data. These values can be used as reference data for women in this age group.