Variation in serum cortisol thresholds and use of salivary cortisol/cortisone in the biochemical diagnosis of adrenal insufficiency (AI) in the UK: Results from the Society for Endocrinology survey

Vladimir Vaks; Miguel Debono; Yasir Elhassan; Sirazum Choudhury; Aparna Pal; Ashley Grossman

doi:10.1530/endoabs.117.P53

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Endocrine Abstracts (2026) 117 P53 | DOI: 10.1530/endoabs.117.P53

SFEBES2026 Poster Presentations Adrenal and Cardiovascular (54 abstracts)

Variation in serum cortisol thresholds and use of salivary cortisol/cortisone in the biochemical diagnosis of adrenal insufficiency (AI) in the UK: Results from the Society for Endocrinology survey

Vladimir Vaks ¹ , Miguel Debono ² , Yasir Elhassan ³ , Sirazum Choudhury ⁴ , Aparna Pal ⁵ & Ashley Grossman ⁶

Author affiliations

¹Great Western Hospitals NHS Foundation Trust, Swindon, United Kingdom; ²Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, United Kingdom; ³University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom; ⁴Imperial College Healthcare NHS Trust, London, United Kingdom; ⁵Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom; ⁶Royal Free London NHS Foundation Trust & University of Oxford, London, United Kingdom

Introduction: Since the introduction of modern cortisol immunoassays, many clinical teams have changed cortisol thresholds in the biochemical diagnosis of AI. The aim of this survey was to evaluate the current practice among UK endocrinologists.

Methods: An online anonymous cross-sectional survey, comprising of 27 multiple-choice questions was developed and disseminated to members of the Society for Endocrinology in July and October 2024.

Results: Forty-three responses from 35 NHS Trusts were received. Respondents worked in both university (n = 12; 34.3%) and district general (n = 23; 65.7%) hospitals. Several cortisol immunoassays platforms are in use with the Roche assay the most common (54.3%). In 90.5% of respondents, 9am or random cortisol threshold was used prior to selecting patients for a Short Synacthen test (SST). However, there were considerable variations in threshold above which cortisol level was considered sufficient to exclude AI (200-400nmol/l), and that indicative of adrenal insufficiency (between <50 and 150nmol/l). Thirty-minute SST responses were used by 57% of Trusts, with 40% using 30- and 60-minute values. Thirty- and 60-minute cut-offs ranged between 380 to 450nmol/l and 375 to 500nmol/l, respectively. The term “subnormal response” was employed by 64% of clinicians with wide threshold range. Insulin tolerance tests are used by 44% of respondents, predominantly for pituitary patients. An adequate response varied between 415 to 500nmol/l, with 25% classifying “subnormal responses” Currently, 20% of Trusts use salivary cortisol/cortisone in current clinical practice analysing the sample by LC-MS/MS.

Conclusions: There are marked variations in current clinical practice in the UK regarding serum cortisol thresholds in the biochemical diagnosis of AI, even using measurement of cortisol by the same immunoassay. However, some Trusts have already started to use salivary cortisol/cortisone, measured by LC-MS/MS. Consensus to establish cortisol thresholds for different modern immunoassays in the biochemical diagnosis of AI is essential.