Overview of Congenital Hypopituitarism for the Neonatologist

Diagnosing and treating anterior pituitary hormone deficiency in pediatric patients

Hypopituitarism, or the failure to secrete hormones produced by the anterior pituitary (adenohypophysis) and/or to release hormones from the posterior pituitary (neurohypophysis), can be congenital or acquired. When more than one pituitary hormone axis is impaired, the condition is known as combined pituitary hormone deficiency (CPHD). The deficiency may be primarily due to a hypothalamic or to a pituitary disorder, or concomitantly both, and has a negative impact on target organ function. This review focuses on the pathophysiology, diagnosis and management of anterior pituitary hormone deficiency in the pediatric age. Congenital hypopituitarism is generally due to genetic disorders and requires early medical attention. Exposure to toxicants or intrauterine infections should also be considered as potential etiologies. The molecular mechanisms underlying the fetal development of the hypothalamus and the pituitary are well characterized, and variants in the genes involved therein may explain the pathophysiology of congenital hypopituitarism: mutations in the genes expressed in the earliest stages are usually associated with syndromic forms whereas variants in genes involved in later stages of pituitary development result in non-syndromic forms with more specific hormone deficiencies. Tumors or lesions of the (peri)sellar region, cranial radiation therapy, traumatic brain injury and, more rarely, other inflammatory or infectious lesions represent the etiologies of acquired hypopituitarism. Hormone replacement is the general strategy, with critical periods of postnatal life requiring specific attention.

The utility of a random cortisol level in determining neonatal central adrenal insufficiency

OBJECTIVES

While it has been established within the first 4 months of life that there is no circadian rhythm, what is unclear is the usefulness of a random serum cortisol (rSC) level in determining neonatal central adrenal insufficiency (CAI). The objective of the study is to determine the utility of using rSC in infants less than 4 months old in the evaluation of CAI.

DESIGN AND PATIENTS

Retrospective chart review of infants who underwent a low dose cosyntropin stimulation test ≤4 months of life with rSC taken as baseline cortisol before stimulation. Infants were divided into three groups: those diagnosed with CAI, those at risk for CAI (ARF-CAI) and a non-CAI group. Mean rSC for each group was compared, and ROC analysis was used to identify rSC cut-off for the diagnosis of CAI.

RESULTS

Two hundred and fifty one infants with the mean age of 50.5 ± 38.08 days, and 37% of these were born at term gestation. The mean rSC were lower in the CAI group (1.98 ± 1.88 mcg/dl) as compared to the ARF-CAI (6.27 ± 5.48 mcg/dl, p = .002) and non-CAI (4.6 ± 4.02 mcg/dl, p = .007) groups. ROC analysis identified a cut-off of rSC level of 5.6 mcg/dL is associated with 42.6% sensitivity and 100% specificity for the diagnosis of CAI in term infants.

CONCLUSIONS

This study demonstrates that though an rSC can be used within the first 4 months of life, its value is best when done ≤30 days of life. Moreover, a diagnostic cut-off for CAI using rSC levels was identified for term infants.