The assessment of urinary sexual hormones within minipuberty and correlations with anthropometrics in a cohort of healthy term children.

Introduction: Minipuberty follows different trends in boys and girls. Aim of our study was to explore timing and dynamics of minipuberty in healthy infants, analyzing urinary levels of sexual hormones. Moreover, we analyzed the association among HPG axis activity and linear growth, ano-genital distances (AGDs) in both sexes, and penile length in males.

Methods: Longitudinal cohort study in healthy term infants from birth to 6 months of life. Clinical evaluation (anthropometrics and AGDs) and urine sampling were performed at 0 (T0), 3 (T3), and 6 (T6) months. Urine samples were analyzed for gonadotropins and sex hormones.

Results: 165 participants were involved. The growth trend of our population was regular, as were the AGDs. Urinary hormones were correlated each other's. Specifically, in boys, the correlation coefficient between urinary FSH (uFSH) and urinary LH (uLH) decreased from T0 to T6, while between urinary Testosterone (uT) and uFSH increased. In girls, correlations between uFSH and urinary Estradiol (uE) were observed at each time point. Notably, several correlations between hormones and anthropometrics and AGDs were found; the most interesting correlation was found in males within uLH and PL (at T0 ρ: 0.323, p < 0.05 and at T3 ρ: 0.371, p < 0.01), whereas in females uFSH at T0 showed negative correlations with both length and body weight percentile at T3 (ρ: -0.505, p < 0.01 and ρ: -0.478, p < 0.01, respectively).

Conclusion: Urinary matrix has proved to be a valuable, practical, non-invasive and cheaper method for sexual hormone assessment.