In pediatric patients, basal
testosterone and
gonadotropin levels may be uninformative in the assessment of testicular function. Measurement of serum anti-Müllerian
hormone (AMH) has become increasingly widespread since it provides information about the activity of the male gonad without the need for dynamic tests, and also reflects the action of FSH and
androgens within the testis. AMH is secreted in high amounts by Sertoli cells from fetal life until the onset of puberty. Basal AMH expression is not dependent on
gonadotropins or sex
steroids; however, FSH further increases and
testosterone inhibits AMH production. During puberty,
testosterone induces Sertoli cell maturation, and prevails over FSH on AMH regulation. Therefore, AMH production decreases. Serum AMH is undetectable in patients with congenital or acquired anorchidism, or with complete
gonadal dysgenesis. Low circulating levels of AMH may reflect primary testicular dysfunction, e.g. in certain patients with
cryptorchidism, monorchidism, partial
gonadal dysgenesis, or central
hypogonadism. AMH is low in boys with
precocious puberty, but it increases to prepubertal levels after successful treatment. Conversely, serum AMH remains at high, prepubertal levels in boys with constitutional delay of puberty. Serum AMH measurements are useful, together with
testosterone determination, in the diagnosis of patients with
ambiguous genitalia: both are low in patients with
gonadal dysgenesis, including
ovotesticular disorders of sex development,
testosterone is low but AMH is in the normal male range or higher in patients with disorders of
androgen synthesis, and both
hormones are normal or high in patients with
androgen insensitivity. Finally, elevation of serum AMH above normal male prepubertal levels may be indicative of rare cases of
sex-cord stromal tumors or Sertoli cell-limited disturbance in the
McCune Albright syndrome.