Cosyntropin: evidence, FDA status and research

A hospital test drug that checks whether the adrenal glands, which make stress hormone, are working. Data from 679 patients show the test sorts sick from healthy well.

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Cosyntropin carries no wellness hype; it is a hospital and clinic diagnostic, and the only online debate is whether the standard or low-dose test is more accurate.

Studies say

Pooled data from 679 patients show the cosyntropin stimulation test reliably separates adrenal insufficiency from normal function, which supports an A for its diagnostic use.

Why grade A. The use cosyntropin is known for is the ACTH stimulation test, and the evidence is diagnostic-accuracy data, with no treatment trials. A meta-analysis pooled patient-level data from 13 studies with 679 subjects and found the test discriminates adrenal insufficiency well, with the low-dose version performing better than the standard dose for chronic pituitary-related insufficiency. Decades of routine clinical use rest on this kind of validation. ¹²

FDA. Cosyntropin is FDA-approved as Cortrosyn (cosyntropin for injection), a diagnostic agent for screening patients presumed to have adrenocortical insufficiency; it is not approved as a treatment for anything. ²

Written from 2 cited sources. Fact-checked 2026-10-27: 11 claims checked, 0 corrected. Last refreshed 2026-10-27. Not physician reviewed.

What this means for you

What people take it for: A medical test for adrenal gland problems.
Can a US doctor prescribe it?: Yes, FDA approved for testing for adrenal gland failure; it is not a treatment.
Properly tested in people?: Yes, in large controlled trials as a test: 679 patients across 13 studies.

Evidence checklist

Randomised controlled trial Diagnostic accuracy studies, not treatment trialsno information
Human study over 100 people Pooled 679 subjects across 13 studiesyes
More than one research group Meta-analysis of studies from many groupsyes
Clinical outcomes, not surrogate markers Test accuracy against reference diagnosesyes
Human safety data beyond case reports Label data; single-dose useyes

Drawn from the cited studies below. A dash means the sources give no information.

What it is

Cosyntropin is a lab-made peptide. It is the first 24 amino acids of adrenocorticotropic hormone (ACTH). That piece carries all of ACTH's activity. So it drives the adrenal glands just as the full 39-amino-acid hormone does. Older corticotropin extracts held animal protein. Cosyntropin does not. ²

It is sold as Cortrosyn and as generics. Doctors give it once, as a test. It goes in by intravenous or intramuscular injection. Blood cortisol is measured before the shot and 30 to 60 minutes after. ²

How it works

Cosyntropin binds the melanocortin-2 receptor on cells of the adrenal cortex. This triggers a burst of cortisol. A healthy adrenal gland responds within half an hour. Blood cortisol rises clearly. Some glands respond weakly or not at all. One cause is a gland that has been destroyed (primary adrenal insufficiency). Another is a gland that has shrunk because the pituitary stopped sending ACTH (secondary insufficiency). The test picks this up. ²¹

What human research shows

Kazlauskaite and colleagues searched the studies from 1966 to 2006. They got patient-level data from 13 of 23 eligible studies. That covered 679 subjects. They compared two tests, standard-dose and low-dose cosyntropin. They checked each against reference diagnoses of hypothalamic-pituitary-adrenal insufficiency. The measure was the area under the ROC curve. It shows how well a test tells disease from health. A score of 1.0 is perfect. The low-dose test scored 0.92. The standard-dose test scored 0.79. Seven studies gave both tests to the same 254 patients. There the low-dose test did better (0.94 versus 0.85). ¹

The authors concluded that the low-dose test is more accurate for chronic secondary insufficiency. They noted practical problems. The low dose must be diluted from the standard vial. Small errors in dilution change the result. ¹

Study	Model	Finding
Kazlauskaite 2008 meta-analysis	Humans, 13 studies, n=679, patient-level diagnostic-accuracy meta-analysis	Low-dose test AUC 0.92 versus 0.79 for standard dose; paired comparison 0.94 versus 0.85. ¹
Cortrosyn FDA label	Regulatory summary	Approved as a diagnostic for screening adrenocortical insufficiency; adverse reactions mostly hypersensitivity. ²

Safety

Cosyntropin is given once. So side effects are rare and brief. The label lists hypersensitivity reactions, including rash, flushing and, rarely, anaphylaxis. It also lists brief bradycardia, tachycardia or hypertension. People who have had an allergic reaction to ACTH products are most at risk. There are no long-term safety questions, because there is no long-term exposure. ²

Questions for your clinician

What do the test results mean for my adrenal function?
Does the low-dose or standard-dose test suit my situation?
Should I mention past reactions to ACTH products?

Questions people ask

Is cosyntropin FDA-approved?

Yes, as Cortrosyn and generics. It is approved for diagnostic screening of adrenocortical insufficiency. It is not approved to treat any condition. ²

What is the cosyntropin stimulation test?

A nurse draws a blood cortisol level and injects cosyntropin. Cortisol is drawn again after 30 to 60 minutes. A normal adrenal gland shows a clear rise. A flat response points to adrenal insufficiency. Either the adrenal glands are damaged, or the pituitary has stopped signalling them. ²¹

Low-dose or standard-dose test: which is better?

A meta-analysis of 679 patients found the low-dose test more accurate for chronic pituitary-related insufficiency (ROC area 0.92 versus 0.79). But the low dose must be diluted by hand. That adds errors. So many centres still use the standard dose. ¹

Is cosyntropin the same as corticotropin?

No. Cosyntropin is a lab-made 24-amino-acid piece of ACTH. It is used once as a test. Corticotropin (Acthar Gel) is the full natural hormone in slow-release form. It is used as a treatment. ²

Citations

Kazlauskaite 2008, J Clin Endocrinol Metab: corticotropin tests for hypothalamic-pituitary-adrenal insufficiency, meta-analysis doi.org
FDA label, 2023: Cortrosyn (cosyntropin for injection) accessdata.fda.gov