A high-sensitivity test in the assessment of adrenocortical insufficiency: 10 microg vs 250 microg cosyntropin dose assessment of adrenocortical insufficiency.

The short cosyntropin (synthetic ACTH) test is recognized as the best screening manoeuvre in the assessment of adrenocortical insufficiency. Recent data, however, suggest that i.v. administration of 250 microg cosyntropin could be a pharmacological rather than a physiological stimulus, losing sensitivity for detecting adrenocortical failure. Our objective was to compare 10 vs 250 microg cosyntropin in order to find differences in serum cortisol peaks in healthy individuals, the adrenocortical response in a variety of hypothalamic-pituitary-adrenal axis disorders and the highest sensitivity and specificity serum cortisol cut-off point values. The subjects were 83 healthy people and 37 patients, the latter having Addison's disease (11), pituitary adenomas (7), Sheehan's syndrome (9) and recent use of glucocorticoid therapy (10). Forty-six healthy subjects and all patients underwent low- and standard-dose cosyntropin testing. In addition, 37 controls underwent the low-dose test. On comparing low- and standard-dose cosyntropin testing in healthy subjects there were no statistical differences in baseline and peaks of serum cortisol. In the group of patients, 2 out of 11 cases of Addison's disease showed normal cortisol criterion values during the standard test but abnormal during the low-dose test. In our group of patients and controls, the statistical analysis displayed a better sensitivity of the low-dose vs standard-dose ACTH test at 30 and 60 min. In conclusion, these results suggest that the use of 10 microg rather than 250 microg cosyntropin i.v. in the assessment of suspicious adrenocortical dysfunction gives better results.