Circulating antimüllerian hormone levels in boys decline during early puberty and correlate with inhibin B.

OBJECTIVE: To investigate peripheral levels of inhibin B and antimüllerian hormone (AMH) in boys during peripuberty and in patients with congenital hypogonadotropic hypogonadism (HH).

DESIGN: Randomized, placebo-controlled trial (peripubertal boys); and cross-sectional clinical study (males with HH).

SETTING: University central hospital.

PATIENT(S): Twenty-eight peripubertal boys with idiopathic short stature (ISS), 19 males with Kallmann syndrome.

INTERVENTION(S): Letrozole (2.5 mg/day) or placebo in boys with ISS for 2 years.

MAIN OUTCOME MEASURE(S): Longitudinal follow-up observation of serum AMH and its relationship with inhibin B during early puberty and the influence of high (letrozole-treated boys) and low (males with HH) gonadotropin exposure on circulating AMH.

RESULT(S): In boys with ISS receiving placebo, the decrease in AMH levels and the increase in inhibin B levels were correlated. The serum AMH level had already declined before a clinically significant increase in testis volume or serum testosterone occurred. Letrozole did not appear to modulate the decline in AMH. The AMH levels were lower in boys and young adults with Kallmann syndrome and prepubertal testes (mean: 20.9 ± 4.7 ng/mL, n = 6) as compared with prepubertal ISS boys (102.3 ± 11.9 ng/mL).

CONCLUSION(S): The gonadotropin-mediated early pubertal increase in inhibin B is tightly coupled to decrease in AMH levels and may reflect androgen-mediated differentiation of Sertoli cells. Profound gonadotropin deficiency is associated with low AMH levels, suggesting impaired development of the Sertoli cell population.