Hypogonadotropic Hypogonadism in Infants with Congenital Hypopituitarism: A Challenge to Diagnose at an Early Stage.

Background: Combined pituitary hormone deficiency (CPHD) presents a wide spectrum of pituitary gland disorders. The postnatal gonadotropic surge provides a useful period to explore the gonadotropic axis for assessing the presence of congenital hypogonadotropic hypogonadism (CHH).

Aim: To explore the functioning of the hypothalamic-pituitary-gonadal axis in the postnatal gonadotropic surge for an early diagnosis of CHH in newborns or infants suspected of having CPHD.

Subjects And Methods: A cohort of 27 boys under 6 months and 19 girls under 24 months of age with suspected hypopituitarism was studied. Serum concentrations of LH, FSH, testosterone, inhibin B, anti-Müllerian hormone (AMH) and estradiol were measured, and male external genitalia were characterized as normal or abnormal (micropenis, microorchidism and/or cryptorchidism).

Results: CPHD was confirmed in 36 out of 46 patients. Low LH and testosterone levels were found in 66% of the hypopituitary males, in significant association with the presence of abnormal external genitalia. This abnormality had a positive predictive value of 93% for CHH. No significant association was observed between serum FSH, AMH and inhibin B and the patient's external genitalia.

Conclusion: In newborn or infant boys with CPHD, LH and testosterone concentrations measured throughout the postnatal gonadotropic surge, together with a detailed evaluation of the external genital phenotype, facilitate the diagnosis of CHH at an early stage.