Suzanne Brown1, Narelle Hadlow2,3, Imran Badshah1, David Henley1,3. 1. Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, WA, Australia. 2. Department of Biochemistry, PathWest Laboratory Medicine, Sir Charles Gairdner Hospital, Nedlands, WA, Australia. 3. School of Medicine and Pharmacology, University of Western Australia, Perth, WA, Australia.
Abstract
OBJECTIVE: Cortisol cut-offs can predict requirement for Synacthen stimulation tests (SST). We assessed the performance of a standard cortisol cut-off (375 nmol/L) across the morning and compared this with a time-adjusted cut-off. DESIGN: Retrospective audit PATIENTS: Community reference set (n=12 550) and SST patients (n=757). MEASUREMENTS: In the reference population, time-specific cortisol medians were calculated and used to convert cortisol to time-adjusted Multiples of the Median (MoM). In 757 SST patients, the predictive performance of a standard cortisol cut-off (375 nmol/L) and its time-adjusted MoM equivalent were compared. RESULTS: Median cortisol decreased by ~30 nmol/L per hour between 0700 and 1200h. In the reference population, proportions below the 375 nmol/L cut-off increased throughout the morning (range 35%-64%), whereas using the time-adjusted MoM cut-off proportions were consistent (range 46%-50%), with a 17% maximal difference in referral rates between the two cut-offs after 1100h. A similar pattern was noted in the SST cohort. When a cortisol MoM cut-off was used to predict SST success, the excess proportion of patients tested and misclassification rates were lower and more consistent than when the standard cut-off was used. A median cortisol of 375 nmol/L equated to 444 and 313 nmol/L before 0800 and after 1100 h, respectively. CONCLUSION: The use of a standard cortisol cut-off results in 17% more patients being referred for SST later in the morning. A time-adjusted cortisol cut-off provides consistent and lower referral rates, whilst maintaining similar or better performance than a standard single cut-off in predicting outcome of SST.
OBJECTIVE: Cortisol cut-offs can predict requirement for Synacthen stimulation tests (SST). We assessed the performance of a standard cortisol cut-off (375 nmol/L) across the morning and compared this with a time-adjusted cut-off. DESIGN: Retrospective audit PATIENTS: Community reference set (n=12 550) and SST patients (n=757). MEASUREMENTS: In the reference population, time-specific cortisol medians were calculated and used to convert cortisol to time-adjusted Multiples of the Median (MoM). In 757 SST patients, the predictive performance of a standard cortisol cut-off (375 nmol/L) and its time-adjusted MoM equivalent were compared. RESULTS: Median cortisol decreased by ~30 nmol/L per hour between 0700 and 1200h. In the reference population, proportions below the 375 nmol/L cut-off increased throughout the morning (range 35%-64%), whereas using the time-adjusted MoM cut-off proportions were consistent (range 46%-50%), with a 17% maximal difference in referral rates between the two cut-offs after 1100h. A similar pattern was noted in the SST cohort. When a cortisol MoM cut-off was used to predict SST success, the excess proportion of patients tested and misclassification rates were lower and more consistent than when the standard cut-off was used. A median cortisol of 375 nmol/L equated to 444 and 313 nmol/L before 0800 and after 1100 h, respectively. CONCLUSION: The use of a standard cortisol cut-off results in 17% more patients being referred for SST later in the morning. A time-adjusted cortisol cut-off provides consistent and lower referral rates, whilst maintaining similar or better performance than a standard single cut-off in predicting outcome of SST.
Authors: H Philpott; M K Dougherty; C C Reed; M Caldwell; D Kirk; D J Torpy; E S Dellon Journal: Aliment Pharmacol Ther Date: 2018-03-05 Impact factor: 8.171
Authors: Ravikumar Ravindran; Joanne L Carter; Asit Kumar; Florin Capatana; Ishrat N Khan; Mohamed A Adlan; Lakdasa D Premawardhana Journal: Clin Med Insights Endocrinol Diabetes Date: 2022-05-06