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

Abstract

AbstractObjectivesWhile 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 PatientsRetrospective 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.ResultsTwo 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.ConclusionsThis 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.