Cosyntropin/cortrosyn stimulation test


Cosyntropin (Cortrosyn) stimulation test, serum or plasma

SST, light green PPT, or lavender


First draw a cortisol level. Then administer cosyntropin (250 mcg IV or IM). Draw another cortisol level in 30 to 60 minutes.

Physiologic Basis

Cosyntropin (also known as Cortrosyn, a synthetic peptide analogue of ACTH) stimulates the adrenal to release cortisol.

A normal response is a doubling of basal levels or a significant increase to a level above 20 mcg/dL (>552 nmol/L).

A poor cortisol response to cosyntropin indicates adrenal insufficiency (see Adrenocortical insufficiency algorithm, Figure 9–3).


Decreased in: Acute adrenal insufficiency (adrenal crisis), chronic adrenal insufficiency (Addison disease), pituitary insufficiency, AIDS.


ACTH stimulation test itself does not distinguish primary from secondary (pituitary) chronic adrenal insufficiency, because in secondary adrenal insufficiency the atrophic adrenal may be unresponsive to cosyntropin. Test may not reliably detect pituitary insufficiency.

Metyrapone test may be useful to assess the pituitary-adrenal axis.

Serum/plasma baseline ACTH is markedly elevated if patient has primary adrenal disease, whereas ACTH is decreased in secondary (pituitary) adrenal insufficiency.

AIDS patients with adrenal insufficiency may have normal ACTH stimulation tests.

Charmandari E et al. Adrenal insufficiency. Lancet 2014;383:2152.  [PMID: 24503135]

Husebye ES et al. Consensus statement on the diagnosis, treatment and follow-up of patients with primary adrenal insufficiency. J Intern Med 2014;275:104.  [PMID: 24330030]

Raff H et al. Physiological basis for the etiology, diagnosis, and treatment of adrenal disorders: Cushing’s syndrome, adrenal insufficiency, and congenital adrenal hyperplasia. Compr Physiol 2014;4:739.  [PMID: 24715566]