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Cosyntropin may help diagnose adrenal insufficiency
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The diagnosis of adrenal insufficiency may be made using the serum free cortisol response to cosyntropin as an alternative to serum total cortisol, according to recent findings.
Lynnette K. Nieman, MD, of the Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, and colleagues evaluated 27 healthy controls, 19 patients with primary adrenal insufficiency, 24 with secondary adrenal insufficiency and 15 with Child-Pugh Class A cirrhosis to determine the efficacy of the cosyntropin simulation test on determining serum free cortisol responses.
All participants received 250 µg cosyntropin with measurements of adrenocorticotropic hormone (ACTH) and corticosteroid-binding globulin at time 0, as well as total cortisol and serum free cortisol at 0, 30 and 60 minutes. In the cirrhosis group, salivary cortisol was measured at all time points.
Compared with the primary adrenal insufficiency group, peak serum free cortisol and total cortisol were higher in the secondary adrenal insufficiency group (P < .05 for both). Controls and the cirrhosis group had higher baseline total and free cortisol compared with the adrenal insufficient groups (P < .0001).
To correctly diagnose adrenal insufficient patients vs. controls, the optimal peak serum free cortisol criterion was 0.9 µg/dL with 95% sensitivity and 100% specificity.
Mean albumin levels and meal corticosteroid-binding globulin levels were similar across all participants.
“This study demonstrates that the serum free cortisol response to cosyntropin is an alternative to serum total cortisol for the diagnosis of adrenal insufficiency, and its use should be considered in patients with protein abnormalities, specifically those with abnormal [corticosteroid-binding globulin] levels, while total cortisol can be used in patients with normal protein levels,” the researchers wrote. “The normative database for serum free cortisol responses to ACTH stimulation may be clinically useful in the assessment of adrenal function.”
A peak serum free cortisol cutoff of 0.9 µg/dL is recommended by the researchers to differentiate patients with adrenal insufficiency from healthy patients. – by Amber Cox
Disclosure: The researchers report no relevant financial disclosures.
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