Cosyntropin Products | Cleanchem - Cosyntropin is a synthetic form of adrenocorticotropic hormone (ACTH) used to evaluate adrenal gland function. It stimulates the adrenal cortex to produce cortisol, making it useful in diagnosing adrenal insufficiency such as Addison? disease. Administered by injection, the cosyntropin stimulation test measures cortisol response. It is essential for distinguishing primary from secondary adrenal insufficiency.