| Objective To detect the levels of total N-terminal propeptide of type 1 precollagen (tP1NP), β cross-linked C-telopeptide of type 1 collagen(β-CTX) and osteocalcin(OC) in the serum of healthy adults in Chengdu area, and to establish their reference intervals. Methods To collect fasting serum from the subject, and the levels of serum tP1NP, β-CTX and OC were measured by electrochemiluminescence immunoassay. Male and female aged from 20 to 77 years old were included, and each group was divided into 5 years old. The locally weighted scatterplot smoothing (LOWESS) method was used to describe the scatter plot of various indicators of different genders with age. And determine the specific age of the reference population. The reference interval of each index and their upper and lower 90% confidence intervals were established. Results 1325 subjects were enrolled, 11 groups for each gender. Respectively, the anerage ages of males and females were 43.0±10.6 years and 37.7±10.1 years. The overall level of serum tP1NP, β-CTX and OC and the levels of each group did not obey the normal distribution (P＜0.001). The levels of various indicators decreased with age before the age of 30, and there was a relatively stable plateau period between the ages of 30 and 59. The levels of various indicators in males over 60 still showed a downward trend with age, while in females, the opposite was true. The age groups with relatively stable distribution and no significant difference of serum tP1NP, β-CTX and OC levels between groups were 35-59 years old for males and 35-49 years old for females（P＞0.05）, which were used as the reference population of healthy adult males and premenopausal females. The reference intervals (P2.5-P97.5) for establishing respective serum tP1NP, β-CTX and OC were 24.20-89.01ng/ml, 0.168-0.791ng/ml and 8.68-27.58ng/ml for healthy adult males and were 21.38-76.03ng/ml, 0.098-0.646ng/ml and 6.60-25.13ng/ml for healthy premenopausal females. Conclusion The levels of serum tP1NP, β-CTX and OC in healthy males aged 35-59 and premenopausal females aged 35-49 in Chengdu are relatively stable with age, and the reference intervals are established based on these. The results are different from the reference range provided by the manufacturer. It is recommended that each region establish a reference interval for bone turnover markers that is suitable for the characteristics of the local population. |