Endocrine Abstracts

Background: Adrenal insufficiency is a life-threatening condition, which may present in the neonatal period with an array of symptoms, one of which includes conjugated hyperbilirubinaemia. The aim of this study was to review the cortisol tests performed across 2 tertiary neonatal centres and to determine how many were undertaken due to conjugated hyperbilirubinaemia and the outcomes of the babies they were performed on.

Methodology: All cortisol tests taken in infants under 30 days old at the time of testing in Glasgow from 01/01/2021 - 31/12/22 were reviewed. Data on gestational age, birth-weight, biochemistry, outcome of Short Synacthen Test (SST) (if applicable: normal cut-off ≥430nmol/l), prior use of steroids and overall outcome were gathered from hospital electronic networks. A random cortisol ≥250nmol/l was accepted as satisfactory.

Results: In total, 184 cortisol tests were undertaken on 97 neonates at a median (range) age of 3 days (1, 27), approximating 4 tests per month. The median gestational age for the infants was 37 (26, 42) weeks. The most common indications for testing were hypoglycaemia (51%) and conjugated hyperbilirubinaemia (18%). Random cortisol levels were <250 nmol/l in 50 (52%). Of these, 26 (50%) remained low on repeat testing. SST was undertaken in 22 (23%) infants and 5 (23%) children had abnormal results. Four of these neonates went onto regular oral hydrocortisone therapy, with 3 remaining on treatment at 18 months’ follow up due to differing, conclusive diagnoses of adrenal insufficiency. One patient required sick day dosing hydrocortisone for 6 months only prior to a normal SST thereafter. Of the 17 babies with conjugated hyperbilirubinaemia, 7 (41%) went on to have an SST with 2 (28%) subsequently starting oral steroids. Only 1 (6%) of these children continues on steroids with a diagnosis of primary adrenal insufficiency. None of the infants who did not have a repeat cortisol or SST have developed adrenal insufficiency.

Conclusion: Low random cortisol levels are not uncommon in the immediate neonatal period, with adrenal insufficiency being confirmed in around 5% of infants tested. Guidance should be followed regarding investigation and management of these abnormal results, as inappropriate management could be potentially life-threatening.