Endocrine Abstracts

Background: The current screening test for adrenal insufficiency (AI) involves patients attending hospital for an “early” morning serum cortisol sample, generally taken some considerable time after the child has woken. This risks missing the morning cortisol peak, leading to false positive results. It requires venepuncture, which is unpleasant for children. Saliva collection is non-invasive, simple and can be undertaken on waking at home, providing a more physiological assessment. Home waking salivary cortisone has proven an accurate screening test for AI in adults (1), and we have investigated its use in children.

Methods: A prospective diagnostic accuracy study was performed in children attending Sheffield Children’s Hospital for a Short Synacthen Test (SST). Patients collected a waking salivary sample at home on the morning of their SST. Salivary cortisol (SalF) and salivary cortisone (SalE) were measured by liquid chromatography-tandem mass spectrometry. Area under Receiver-operator characteristic (AuROC) curves were computed, and cut-off accuracies derived. Patient and carer acceptability were investigated using questionnaires.

Results: Seventy-eight patients have completed the study to date, 68 with adequate samples for analysis. Mean age was 10.6 years (SD 3.4, range 3-17 years), 52% female and 60% taking steroid medication. The prevalence of AI (defined as a peak serum cortisol post 145 mg/m2 Synacthen of <430nmol/L) was 19% (n=13). Waking salivary glucocorticoids predicted SST outcome with an AuROC of 0.76 (95% CI 0.60-0.92, P=0.004) for SalF and 0.83 (95% CI 0.73-0.93, P=0.000) for SalE. A waking SalE cut-off of >13.9nmol/L excluded AI with a sensitivity of 92% and a negative predictive value of 97% and would have avoided 35 (45%) SSTs. The home test was acceptable to 97%, with 86% preferring the salivary test over the SST.

Conclusions: Our data indicate that waking salivary cortisone provides an accurate, acceptable and more convenient screening test for AI. Paediatric cut-offs may be different to those recently reported in adults (1). Home waking salivary cortisone has the potential to shorten the AI diagnostic pathway, reduce false positive screen results, enabling more tailored SST diagnostic testing. Further work is needed to support implementation throughout the NHS.1. NEJM Evid 2023;2(2) DOI:10.1056/EVIDoa2200182