Utility of First-Morning-Voided Urinary Total Luteinizing Hormone in Detecting the Onset of Central Puberty.

Introduction: Early morning basal serum luteinizing hormone (S-LH) ≥0.3 IU/L is a specific marker for the onset of central puberty. In this study, we aimed to investigate the sensitivity and specificity of the first-morning-voided (FMV) total urinary LH (U-LH) to replace this marker.

Methods: We re-analyzed our previously published data set of 297 children (145 boys and 152 girls, aged 5-15 years, across Tanner stages 1 through 5) using receiver operating characteristic (ROC) analysis and determined cutoff values for FMV total U-LH in predicting early morning S-LH concentration at or above 0.3 IU/L. We also determined S-LH and serum follicle-stimulating hormone (S-FSH) concentrations in girls at different stages of sexual maturation.

Results: ROC analysis showed that FMV total U-LH levels of 0.60 and 0.63 IU/L in girls and boys, respectively, predicted early morning S-LH levels of 0.3 IU/L or higher with 97.4% sensitivity and 90.6% specificity. Higher cutoff levels for U-LH (0.78 IU/L for boys and 0.79 IU/L for girls) yielded 94.7% specificity at the expense of a relatively lower level of sensitivity (94.1%). The areas under the curve were 0.98 in boys and 0.99 in girls, respectively. Additionally, the increase in FMV total U-LH (or S-LH) levels identified the activation of central pubertal development at the mean age of 10.3 (10.3) in boys and 10.5 (10.6) in girls. The S-FSH concentrations of the six biochemically prepubertal girls with thelarche, ranging between 2.3 and 2.7 IU/L, were significantly higher than those measured in biochemically and clinically prepubertal girls of the same 10-12-year-old age group and significantly lower than those measured in both biochemically and clinically pubertal girls (p = 0.039 and p = 0.018, respectively).

Conclusions: A FMV total U-LH concentration of 0.6 IU/L or above reliably reflects pubertal morning S-LH levels and is effective in detecting the onset of central puberty, which occurs at similar ages in both sexes. Concurrent S-FSH or noninvasive FMV U-FSH determinations may be useful in the differential diagnosis of isolated thelarche.