Abstract
Inhibin B (INHB) is an emerging biomarker of sexual function diseases, but its clinical use in children is hindered due to the lacking reference intervals (RIs) based on age and sex. A total of 622 healthy Chinese children including 48.6% females and 51.4% males were included and serum INHB and six conventional sex hormones were measured. INHB was partitioned by four predetermined age groups (< 1 year, 1-5 years, 5-10 years, 10-18 years) and the corresponding RIs were determined with quantile. The effect of age on INHB was assessed using five models including linear, quadratic, cubic, S, and logarithmic. Spearman correlation was used to examine the associations between INHB and sex hormones. Compared to the boys, girls had lower median concentrations and variability in INHB across all four age groups. The optimal models for the effect of age on INHB were cubic (R(2) = 0.440 for boys and R(2) = 0.198 for girls). The median INHB concentrations in the youngest and oldest age groups for girls were higher than the two intermediate age groups and in the youngest age group for boys were higher than other age groups (all P ≤ 0.001). Spearman's correlation analysis showed the sex-dependent associations between INHB and conventional sex hormones (e.g. a positive association with PRL in boys). INHB level is influenced by age and sex, and our results provide specific RIs to facilitate screening sexual function diseases in Chinese children.