Urinary gonadotrophins: a useful non-invasive marker of activation of the hypothalamic pituitary-gonadal axis

BACKGROUND: Non-invasive screening investigations are rarely used for assessing the activation and progression of the hypothalamic-pituitary gonadal axis through puberty. This study aimed to establish a normal range for urinary gonadotrophins in children progressing through puberty. METHODS: Urine samples were collected from 161 healthy school children (76 boys, 85 girls) aged 4–19 yrs. Height and weight were converted to standard deviation score. Pubertal status, classified by Tanner staging, was determined by self-assessment. Urinary gonadotrophins were measured by chemiluminescent microparticle immunoassay. Results were grouped according to pubertal status (pre-pubertal or pubertal). RESULTS: Of the 161 children, 50 were pre-pubertal (28 boys; 22 girls) and 111 were pubertal (48 boys; 63 girls). Overall, urinary gonadotrophins concentrations increased with pubertal maturation. All pre-pubertal children had a low urinary LH:Creatinine ratio. LH:Creatinine ratios were significantly higher in pubertal compared to pre-pubertal boys (p<0.001). In girls, FSH:Creatinine ratios were significantly higher in the pubertal group (p = 0.006). However, LH:FSH ratios were a more consistent discriminant between pre-pubertal and pubertal states in both sexes (Boys 0.45 pubertal vs 0.1 pre-pubertal; girls 0.23 pubertal vs 0.06 pre-pubertal). CONCLUSION: Urinary gonadotrophins analyses could be used as non-invasive integrated measurement of pubertal status which reflects clinical/physical status.