Can a random serum cortisol reduce the need for short synacthen tests in acute medical admissions?

Abstract

Background: Short synacthen tests (SSTs) are frequently performed in medical inpatients with suspected adrenocortical insufficiency. The utility of a random or baseline serum cortisol in this setting is unclear. We determined random cortisol thresholds that safely preclude SSTs in acute medical admissions. Methods: We analysed SSTs in acute non-critically ill general medical patients (n ¼ 166, median age 66, range 15-94 y; men 48%, women 52%). The SST was defined according to the 30-min cortisol as 'pass' (.550 nmol/L) or 'fail' (550 nmol/L). Receiver operating characteristics (ROC) curves were generated to determine the predictive value of the basal cortisol for a failed SST. Results: Of 166 SSTs, a pass was seen in 127 (76.5%) tests, while 39 (23.5%) tests failed the SST. ROC curves showed that no single cut-off point of the baseline cortisol was adequately both sensitive and specific for failing the SST despite a good overall predictive value (area under curve 0.94; 95% confidence interval 0.89-0.98). A basal cortisol ,420 nmol/L had 100% sensitivity and 54% specificity for failing the SST, while a basal cortisol ,142 nmol/L had 100% specificity and 35% sensitivity. Restricting the SST to patients with a basal cortisol ,420 nmol/L would have prevented 44% of SSTs while correctly identifying all patients who failed the SST. Conclusion: A baseline serum cortisol may prevent unnecessary SSTs in medical inpatients with suspected adrenocortical insufficiency. However, SSTs are still indicated in patients with random cortisol ,420 nmol/L, or where the suspicion of adrenal insufficiency is compelling.

First presentation of Addison's disease as hyperkalaemia in acute kidney injury

“…A diagnosis of primary adrenal insufficiency was suspected, and further blood tests revealed a random serum cortisol level, taken at 10.30, of 49 nmol/L (200–750 nmol/L). This test (despite inherent shortcomings due to imprecision in cortisol assays)6 has been suggested as a useful first test in suspected Addison's disease before conducting any form of adrenocorticotropic hormone (ACTH) stimulation test 7. In this case, a short Synacthen test was attempted and abandoned, as it was impossible to gain further peripheral vascular access due to intravascular hypovolaemia.…”

Validated criteria for the interpretation of a single measurement of serum cortisol in the investigation of suspected adrenal insufficiency

“…For inpatients, comparatively little attention has been given to the use of a single measurement of serum cortisol as an initial step in the approach to suspected AI, although an approach which avoids the need for a carefully timed dynamic test in busy inpatient units is clearly advantageous. Our study addresses this question using predefined criteria and in a much larger cohort than previously published studies . We have found morning basal serum cortisol is highly sensitive and carries the potential for a large reduction in the need for SSTs.…”

“…Furthermore, existing studies allow conclusions to be drawn in the relatively confined clinical setting of outpatients attending in the morning. The performance of the test in samples drawn in the afternoon has not been tested, and relatively little is known about the value of the test in the inpatient setting …”

“…A single measurement of serum cortisol as an initial step in the investigation of AI therefore carries a number of advantages over dynamic testing. Although extensively studied, [6][7][8][9][10][11][12][13][14][15][16][17][18] this remains a contentious approach, and reports of its diagnostic utility, and suggested thresholds, vary considerably. This may reflect challenges in interpreting single measurements of serum cortisol due to its circadian and ultradian variability, 19 assay variation, 17 and the relative rarity of the condition relative to the size of the population tested, meaning a large cohort is required to draw reliable conclusions.…”

Mineralocorticoid responsive hyponatremia of the elderly

“…One report evaluating the relation between random and post-ACTH stimulation cortisol level among acute noncritically ill general medical patients indicated that post ACTH stimulation cortisol level is >20 μg/dL, if random cortisol level is >15.2 μg/dL, indicating that adrenal insufficiency has been ruled out in such cases. [20] For these reasons, the possibility of adrenal insufficiency might not have been ruled out in at least 4 cases in our current review. [5,7,9,10] In addition, cases with recent use of diuretic agent and correction of hyponatremia without the use of fludrocortisone acetate might need to be excluded.…”