Inhibin B in pubertal development and pubertal disorders.

The inhibin B pubertal surge is a prominent signal of gonadal maturation in females as well as in males. In boys, it denotes the final functional maturation of Sertoli cells, which is accompanied by a progressive suppression of antimüllerian hormone production. In girls it reflects the initial recruitment of preantral follicles and their evolution to the antral stage. In both the prepubertal quiescent phase and the active peripubertal phase there is a striking sexual dimorphism, inhibin B levels being significantly higher in boys than in girls, in contrast to follicle-stimulating hormone (FSH) levels. Determining inhibin B levels together with FSH levels is of considerable help for diagnosing disorders of pubertal development. In girls with central precocious precocity, inhibin B levels are in accordance with the clinical stage of maturation, by contrast to normal or low levels in the McCune-Albright syndrome. In boys with delayed puberty, inhibin B levels are very low in congenital defects of the gonadotropin-releasing hormone-FSH-testis axis, but they are normal or intermediate in constitutional delayed puberty. Together with antimüllerian hormone, inhibin B is a useful marker of the presence of Sertoli cells in bilateral cryptorchidism and in the androgen insensitivity syndrome. In addition, inhibin B measurement, together with that of inhibin A, is helpful for the diagnosis and follow-up of inhibin-secreting tumors: granulosa cell tumors in girls and Sertoli cell tumors of the Peutz-Jeghers syndrome in boys. In conclusion, inhibin determination is an essential tool in the assessment of physiological development as well as in the management of pubertal disorders.