ESPE Abstracts

Background: The current screening test for adrenal insufficiency (AI) involves patients traveling to attend hospital for an “early” morning serum cortisol (EMC) sample, generally taken some considerable time after the child has woken. This risks missing the morning cortisol peak, leading to false positive results and necessitating further testing, usually by the Short Synacthen Test (SST). Both EMC and SST require venepuncture, which is resource intensive and unpleasant for children. Saliva collection is non-invasive, simple and can be undertaken shortly after waking at home, providing a more physiological assessment. Home waking salivary cortisone (WSC) is demonstrated to be an accurate screening test for AI in adults (1). We aimed to investigate its accuracy and acceptability in children.

Methods: A prospective feasibility study was performed in children attending Sheffield Children’s Hospital, UK, for an SST. Patients collected a waking salivary sample by passive drool at home on the morning of their SST. Paired blood and saliva samples were taken at 0, 30 and 60 minutes post Synacthen. AI was defined as a peak serum cortisol post 145 mcg/m² Synacthen of <430nmol/L. Serum cortisol levels measured by LC-MS/MS are presented here. Salivary cortisol (SalF) and salivary cortisone (SalE) were measured by LC-MS/MS. Area under Receiver-Operator Characteristic (AuROC) curves were computed. Patient and carer acceptability were investigated using questionnaires.

Results: Of the 107 patients who consented, 79 successfully completed the study and 77 provided a viable WSC sample. Mean age was 10.4 years (SD 3.4, range 3-17 years), 49% female and 43% currently taking steroid medication. The prevalence of AI was 20.3% (n = 16). Waking salivary cortisone and cortisol predicted the SST outcome with an AuROC of 0.79 (95% CI 0.66-0.92) and 0.73 (95% CI 0.58-0.87) respectively. Baseline (0 minute) cortisol was used as a surrogate for EMC (median sampling time 09:15, IQR 09:00-10:00) and had an AuROC of 0.67 (95% CI 0.51-0.84). The home test was acceptable to 94.9% of parents and 92.4% of children, with only 12.7% preferring an in-hospital SST to the home salivary test.

Conclusion: Our data indicate that WSC may provide an accurate, acceptable and more convenient screening test for AI. Home waking salivary cortisone has the potential to reduce false positive screen results, shorten the AI diagnostic pathway and enable more tailored SST diagnostic testing. Further work is needed to define paediatric diagnostic cut-offs and support widespread clinical implementation. 1. NEJM Evid 2023;2(2) DOI:10.1056/EVIDoa2200182