Measurements of serum müllerian inhibiting substance in the evaluation of children with nonpalpable gonads.

BACKGROUND Müllerian inhibiting substance, produced constitutively by the prepubertal testes, promotes involution of the müllerian ducts during normal male sexual differentiation. In children with virilization and nonpalpable gonads, only those with testicular tissue should have detectable serum concentrations of müllerian inhibiting substance. METHODS We measured serum mullerian inhibiting substance in 65 children with virilization at birth and nonpalpable gonads (age at diagnosis, 2 days to 11 years) and serum testosterone in 54 of them either after the administration of human chorionic gonadotropin or during the physiologic rise in testosterone that occurs in normal infants. RESULTS The mean (+/-SD) serum mullerian inhibiting substance concentration in the 17 children with no testicular tissue was 0.7+/-0.5 ng per milliliter, as compared with 37.5+/-39.6 ng per milliliter in the 48 children with testes (P<0.001). In the latter group, the mean values in the 14 children with abnormal testes and the 34 with normal testes were 11.5+/-11.8 and 48.2+/-42.1 ng per milliliter, respectively (P< 0.001). The sensitivity and specificity of the serum müllerian inhibiting substance assay for detecting the absence of testicular tissue were 92 percent and 98 percent, respectively, as compared with 69 percent and 83 percent for the measurement of serum testosterone. Furthermore, measurement of serum mullerian inhibiting substance was more sensitive than serum testosterone measurement for the identification of children with abnormal testes (67 percent vs. 25 percent), whereas the specificity of the two tests was similar. CONCLUSIONS Measurements of serum mullerian inhibiting substance can be used to determine testicular status in prepubertal children with nonpalpable gonads, thus differentiating anorchia from undescended testes in boys with bilateral cryptorchidism and serving as a measure of testicular integrity in children with intersexual anomalies.