Unravelling a novel, promising and convenient tool for differential diagnosis of delayed puberty: GnRHa-stimulated inhibin B (GnRH-iB)

Abstract

Etiological diagnosis of delayed puberty is difficult. Despite availability of various basal and stimulation tests differentiation between constitutional delay in puberty and hypogonadotropic hypogonadism is still challenging. To elucidate the role of GnRH agonist-stimulated inhibin B (GnRH-iB) for the differential diagnosis of delayed puberty. Participants were recruited into "exploratory cohort" (n = 39) and "validation cohort" (n = 16). "Exploratory cohort" included children with spontaneous puberty and patients with hypogonadotropic hypogonadism. "Validation cohort" constituted children who presented with delayed puberty. GnRHa (Triptorelin) stimulation test along with measurement of inhibin B level at 24h after GnRHa injection was performed in all the study participants. Cut-offs for GnRH-iB were derived from the "exploratory cohort". These cut-offs were applied to the "validation cohort". Basal LH, basal inhibin B(INH-B), GnRHa-stimulated LH at 4h (GnRH-LH) and GnRH-iB were evaluated for the prediction of onset of puberty on prospective follow-up. GnRH-iB at a cut-off value of 113.5pg/ml in boys and 72.6pg/ml in girls had 100% sensitivity and specificity for the documentation of puberty. In the "validation cohort" basal LH, basal INH-B, GnRH-LH, and GnRH-iB had a diagnostic accuracy of 68.75%, 81.25%, 68.75% and 93.75% respectively, for the prediction of onset of puberty. Basal LH, basal INH-B and GnRH-LH used alone or in combination were inferior to GnRH-iB used alone. GnRHa-stimulated inhibin B (GnRH-iB) is a convenient and easily employable test for the differentiation of constitutional delay in puberty from hypogonadotropic hypogonadism. CTRI/2019/10/021570.