Corticotrophin-releasing hormone stimulation tests for the infants with relative adrenal insufficiency.

BACKGROUND: Very low birthweight (VLBW) infants are considered to be vulnerable to relative adrenal insufficiency (RAI); however, diagnosis is difficult in some clinical settings. Considering this background, it is necessary to establish a diagnosis of RAI in preterm infants.

OBJECTIVE: In this study, we attempted to clarify the difference in response to CRH stimulation tests for preterm infants with or without RAI.

METHODS: Between June 2009 and December 2015, we performed CRH stimulation tests for preterm infants born at a gestational age of <30 weeks at around 2 weeks of age. Retrospectively, subjects were classified into two groups: infants with RAI (n = 9) or without RAI (n = 17) based on the clinical symptoms and responsiveness to hydrocortisone.

RESULTS: We found no difference in base or peak serum cortisol levels related to CRH stimulation tests between the two groups; however, delta cortisol levels and responsive ratio (peak-to-base ratio) were significantly reduced in infants with RAI. 140 nmol/L for delta cortisol or 1.5 times for peak-to-base ratio may be cut-off levels in preterm infants.

CONCLUSION: This study provides evidence that base cortisol levels of preterm infants with RAI were not different from those without RAI; however, CRH stimulation tests may be a useful tool for the diagnosis of RAI in preterm infants.