Trajectories and characteristics of urinary gonadotropin and sex hormones in healthy 0 – 6 years old children

  Objective  To observe changing trends and characteristics of urinary gonadotropin and sex hormones in healthy children aged 0 – 6 years and to provide preliminary references for researches on mini-puberty and precocious puberty.

  Methods  First morning urinary samples were collected from 920 healthy 0 – 6 years old children (471 boys and 449 girls) in two communities of Wuxi city, Jiangsu province between May 2016 and October 2017; urinary gonadotropin and sex hormones were determined using immunochemiluminometric assay with creatinine (Cr) correction.

  Results  The median (25% percentile P₂₅ – 75% percentile P₇₅) of urinary luteinizing hormone corrected by creatinine (ULH/Cr) was 29.36 (17.72 – 65.05) U/mol and 33.31 (20.47 – 76.46) U/mol in the boys and girls, without significant gender difference. The median (P₂₅ – P₇₅) of urinary follicle stimulating hormone corrected by creatinine (UFSH/Cr) among the boys was 473.37 (304.15 – 758.17) U/mol and was significantly lower than that (2 414.57 1 444.80 – 4 212.84 U/mol) among the girls (t = – 16.61, P < 0.001). The median (P₂₅ – P₇₅) of urinary estriol corrected by creatinine (UE3/Cr) among the boys was 21.58 (16.06 – 32.47) μg/mol and was significantly lower than that (24.18 18.57 – 35.53 μg/mol) among the girls (t =– 0.857, P = 0.001). The median (P₂₅ – P₇₅) of urinary estradiol corrected by creatinine (UE2/Cr) was 34.89 (24.08 –59.87) μg/mol and 32.08 (22.33 – 54.39) μg/mol among the boys and girls, without significant gender difference. The urinary gonadotropin and sex hormone presented a decreasing trend with the increment of age in both the boys and the girls. The decrease in UE2/Cr slows down at the age of 1.5 years and the decreases in other sex hormones slows down at the age of 6 months among the boys; while, among the girls the decreases in ULH/Cr and UE2/Cr slow down at the age of 2 years and the decreases in UFSH/Cr, UE3/C, and urinary progesterone corrected by creatinine (UPro/Cr) slow down at the age of 5 years, 6 months, and 3 years, respectively.

  Conclusion  Urinary gonadotropin and sex hormone decrease with the increment of age and the decreases differ by gender and various hormones among 0 – 6 years old healthy children.