| Abstract:Objective：To establish the continuous percentile curve of carbohydrate antigen 125 (CA125) by coefficient of skewness-median-coefficient of variation (LMS) method, so as to evaluate the age-specific applicability of current reference interval.Methods：CA125 measurements of healthy women enrolled from January to December 2016 were collected. The continuous percentile curve for CA125 value was fitted by using LMS method after the outliers were removed through Turkey method. The age stratification was performed according to the curve and verified by Z-test. Results：A total of 29 992 individuals were finally enrolled after 1015 outliers were eliminated. The current reference interval of CA125 (35 U/mL) was corresponded to the 99.5th percentile. A large decline of CA125 level was observed in those individuals between 40 to 60 years old, and no remarkable change of CA125 was observed in other ages. For those aged from 15 to 40 and those aged from 60 to 95, the median of CA125 level was 17.8 U/mL and 11.5 U/mL, while the 99.5th percentile was 35.5 U/mL and 29.5 U/mL; for those aged from 40 to 45, 45 to 50, 50 to 55 and 55 to 60, the median and 99.5th percentile were 12.9, 11.7, 9.7, 8.7 U/mL and 35.3, 35.4, 33.5, 28.9 U/mL, both showing downward trend. The CA125 level showed significantly difference between groups with 50 as cut-off value of age (Z=54.76, P＜0.001, Z*=4.9).Conclusions：Current upper reference limit of CA125 level (35U/mL) has been approved to be inappropriate for all ages, because CA125 is significantly affected by age. It is necessary to establish the reference interval of CA125 level for different age according to the character of age distribution. |