Reproducibility and Refinement of Urinary LH in the Screening of Progressive Puberty in Girls.

CONTEXT: First-voided urinary LH (FVU-LH) has been suggested as an alternative to GnRH stimulation test for detection of precocious puberty. OBJECTIVE: To evaluate the reproducibility of FVU-LH, its correlation with basal and GnRH-stimulated gonadotropins, and its diagnostic value for differentiating progressive from nonprogressive puberty. DESIGN AND PARTICIPANTS: Clinical and endocrine data were obtained from the medical records of 95 girls with suspected progressive puberty who underwent 2 consecutive FVU-LH tests. In 55 of these participants, GnRH stimulation test was performed close to the FVU-LH test. The reported cutoff levels of 5 IU/L and 1.16 IU/L for GnRH-stimulated LH and FVU-LH, respectively, were used as markers of progressive puberty, clinically defined as bone age advancement of ≥1 year and/or growth velocity SD score ≥2, in addition to thelarche. RESULTS: The 2 consecutive measurements of FVU-LH were highly correlated (r = 0.830; P < 0.001). The higher of the 2 results was better correlated with basal gonadotropins and GnRH-stimulated LH. Furthermore, it aligned better with the clinical outcome of girls with early thelarche, which supports the approach of double tests of FVU-LH to distinguish progressive from nonprogressive puberty. By comparison to GnRH-stimulated LH, the higher FVU-LH value had better sensitivity (68%), whereas peak LH had better specificity (91%) for the diagnosis of progressive puberty. Both tests had high positive predictive value and poor negative predictive value. CONCLUSIONS: The higher value of paired FVU-LH tests can be used to screen girls with suspected progressive puberty and can reduce the need for GnRH stimulation test.