A possible role for reproductive hormones in newborn boys: Progressive hypogonadism without the postnatal testosterone peak

Healthy buys have a considerable production of reproductive hormones during the first postnatal months, the biological significance of which is poorly understood. We report on cases of male infants with hypogonadism (hypogona dotropic hypogonadism, n = 1; panhypopituitarism, n = 2) who showed lack of penile growth and involution of the scrotum. In two buys, diagnoses were o btained in early infancy and hormonal measurements at 3-4 months of age sho wed serum testosterone levels below detection limits in both low inhibin B (37 and 199 pg/mL, respectively; normal range, 193-563 pg/mL) and low to un detectable gonadotropins [LH, undetectable and 0.07 IU/L (normal range, 0.6 5-2.69 IU/L), respectively; FSH, 0.18 IU/L in both (range, 0.86-2.52 IU/L)] . In a third boy, Konadotropin deficiency was diagnosed at 3 yr of age by u ndetectable serum level of FSH and LH both before and after stimulation wit h GnRH. All cases required hormonal treatment with testosterone, administer ed as suppositories in daily doses between 1 and 5 mg, which reintroduced m ale genital development. Our observations suggest that normal phallic and s crotal development in humans is dependent on intact testosterone secretion during early infancy. Additionally, the diagnosis of gonadotropin deficienc y may be established in a short-time window postnatally by measurement of s pontaneous serum concentrations of reproductive hormones.