ESPE Abstracts (2014) 82 P-D-2-3-505

Random Serial Cortisol Levels in Neonates: Does it Reduce Synacthen Testing?

Susannah Pyea, Zoe Smitha & Rakesh Aminb


aHomerton University Hospital, London, UK; bGreat Ormond Street Hospital, London, UK


Background: Diagnosis of adrenal insufficiency in the neonatal period is most accurately diagnosed with a short Synacthen test. Some tertiary endocrinology centres advocate random serial cortisol measurements over a 3-h period; a normal cortisol reading during such a test would negate the need for a Synacthen test.

Objective and hypotheses: Our aim is to assess whether serial cortisol level readings accurately identifies neonates with normal adrenal function, therefore avoiding a Synacthen test. We hypothesise that serial cortisol readings in a neonate generates inconclusive results. In such cases Synacthen testing is the most accurate and reliable way of formally assessing adrenal function.

Method: This retrospective study identified all abnormal cortisol results on neonates at a tertiary centre NICU between June 2012 and December 2013. The notes and lab results of eligible neonates were reviewed to determine how many patients were advised on having serial cortisol level readings, and of those, how many went on to have a short Synacthen test following inconclusive results.

Results: 38 neonates had a random cortisol level requested during the 18-month period. Of those, 18 had an abnormal result. 13 had a further abnormal repeat cortisol level. Four patients had serial cortisol level readings: the results were inconclusive in 3 (75%), and therefore had a formal Synacthen test. None of the patients requiring a Synacthen test had a diagnosis of adrenal insufficiency during the admission.

Conclusion: Although adrenal assessment is relatively rare in the neonatal unit, our results indicate that there was no obvious gain in performing serial cortisol level testing in neonates with abnormal cortisol readings. 75% of neonates who underwent serial cortisol level testing had inconclusive results and required a formal Synacthen test. We conclude that the most accurate and efficient way of assessing adrenal function in neonates continues to be a Synacthen test.

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