FSH-stimulated Inhibin B (FSH-iB): A Novel Marker for the Accurate Prediction of Pubertal Outcome in Delayed Puberty

Abstract

Abstract Background Clinicians have long been struggling to find an effective tool to predict onset of puberty. Objective To explore stimulability of inhibin B after exogenous FSH and its potential role for prediction of onset of puberty. Design and participants Study subjects were enrolled into “exploratory cohort” (n = 42) and “validation cohort” (n = 19). The exploratory cohort was further divided into group 1 (healthy children with spontaneous puberty [SP], n = 26) and group 2 (patients with hypogonadotropic hypogonadism [HH], n = 16). The validation cohort included children who presented with complaints of delayed puberty. Intervention and outcome Participants were subjected to FSH stimulation test and GnRH analogue stimulation test. Cutoffs derived from the exploratory cohort for basal and FSH stimulated inhibin B (FSH-iB) were applied on the validation cohort. Basal LH, GnRH analogue-stimulated LH, basal inhibin B, and FSH-iB were compared with clinical outcomes on a prospective follow-up for prediction of onset of puberty. Results There was statistically significant increment in inhibin B after exogenous FSH in group 1 (SP) in both male (188.8 pg/mL; P = 0.002) and female (1065 pg/mL; P = 0.023) subjects. The increment was not statistically significant in group 2 (HH) in both sexes. FSH-iB at a cutoff of 116.14 pg/mL in males and 116.50 pg/mL in females had 100% sensitivity and specificity for labelling entry into puberty. On application of these cutoffs on the validation cohort, FSH-iB had 100% positive predictive value, negative predictive value, and diagnostic accuracy for prediction of pubertal onset. Conclusion Inhibin B was stimulable in both male and female subjects. FSH-iB can be considered a novel and promising investigation for prediction of onset of puberty. Future studies are required for further validation.