The diagnostic value of first-voided urinary LH compared with GNRH-stimulated gonadotropins in differentiating slowly progressive from rapidly progressive precocious puberty in girls.

OBJECTIVE: Characterization of pubertal progression is required to prevent unnecessary intervention in unsustained or slowly progressive (SP) precocious puberty (PP), while delivering hormonal suppression in rapidly progressive (RP) PP. We aimed to assess the diagnostic value of first-voided urinary LH (ULH) compared with GNRH-stimulated gonadotropins in differentiating these forms of PP.

METHODS: A total of 62 girls with PP underwent both GNRH stimulation and ULH assay. Fifteen girls with peak LH ≥ 10 IU/L started treatment immediately, whereas the other 47 girls were evaluated after 6 months for pubertal advancement, height acceleration, and bone-age maturation. Based on these criteria, the participants were assigned to five subgroups: pubertal regression, no progression or progression by one, two or three criteria. The first three subgroups were defined as SP-PP (n=29), while the other two subgroups were defined as RP-PP (n=18). An additional 23 prepubertal girls were evaluated for ULH.

RESULTS: ULH but not serum gonadotropins could distinguish girls with two and three criteria from less progressive subgroups. By comparison with SP-PP (i.e. regression group and groups 0 and 1), those with RP-PP (group 2+3) had lower peak FSH (9.28±2.51 vs 12.57±4.30; P=0.007) and higher peak LH:FSH ratio (0.42±0.30 vs 0.22±0.12; P=0.022) and ULH (1.63±0.65 vs 1.05±0.26 IU/l; P<0.001). Based on receiver operating characteristics analysis, a ULH cutoff of 1.16 IU/l had a better sensitivity (83%) and positive and negative predictive values (65 and 88% respectively) than the other two parameters, with a specificity of 72%.

CONCLUSIONS: ULH assay is a noninvasive, reliable method that can assist in the distinction between SP- and RP-PP.