Serum levels of mullerian inhibiting substance in boys throughout puberty and in the first two years of life.

Serum levels of Mullerian inhibiting substance (MIS) have been measured in 91 boys throughout normal pubertal development. MIS levels fell sharply after pubertal stage 1 and were mostly undetectable at pubertal stage 6. The relationship between MIS concentration and pubertal stage was similar when compared with age. Seven patients with precocious puberty and 12 with delayed puberty were also investigated and found to have MIS levels consistent with their degree of pubertal development. Precocious puberty was associated with MIS levels that were abnormally low for age, while delayed puberty resulted in persistence of high MIS levels. Serum MIS levels were also measured in 29 boys less than 2 yr of age undergoing minor surgery. High levels were found throughout this time period, which is consistent with previous reports. MIS levels appear to be inversely related to levels of gonadotropins, steroids, and inhibin, which fall in the first 2 yr of life and rise throughout puberty.