Background: There is limited evidence regarding the most appropriate method to investigate adrenal dysfunction in neonates. Our unit in Sheffield, UK measures a series of three serum cortisol levels to determine the need for a short synacthen test (SST). Other units use the SST as the first-line investigation in suspected adrenal insufficiency in neonates; however SST is more invasive with anaphylactic risk.
Objective and hypotheses: To determine the proportion of neonates at risk of adrenal insufficiency who are likely to require SST. Our criteria was that two cortisol levels of >100 nmol/l or one level of >200 nmol/l would indicate normal adrenal function.
Method: By retrospectively analysing a cohort of 154 neonates who underwent cortisol sampling over a 5-year period.
Results: Out of 154 babies, 8(5.1%) had cortisols below the threshold and required SST (one abnormal). The mean random cortisol was 46.3±8.1 and 491.6±833.5 nmol/l for babies requiring and not requiring SST respectively (P<0.0001). Hypoglycaemia (27%), maternal steroids (23%), hypotension (16%) and suspected pituitary anomaly (10%) were the common reasons for adrenal-axis testing. To demonstrate normal adrenal function, 80%(123/154) of neonates required one cortisol and 10%(15/154) required two cortisol tests. Among neonates with hypoglycaemia only 7%(3/41) required two cortisol tests and one required SST (normal). All babies tested due to hypotension required only one cortisol. Of the 16% babies with suspected pituitary dysfunction or congenital adrenal hyperplasia, 8%(2/25) had significantly low cortisol levels requiring steroid replacement; only one of them had SST. Among babies tested due to maternal steroids, 11%(4/36) required SST (normal) and one (3%) was started on steroid replacement prior to SST due to significantly low cortisol levels.
Conclusion: Random cortisol measurement in suspected adrenal insufficiency is an appropriate screening test prior to SST assuming laboratory testing of cortisol is rapid. A SST is indicated if two cortisol measurements are <100 nmol/l.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology