Cosyntropin (acetate) is primarily used in medical diagnostics to assess adrenal gland function. It is administered to stimulate the adrenal cortex, prompting the release of cortisol. This helps in diagnosing conditions like adrenal insufficiency, Addison's disease, or hypopituitarism. Additionally, it is utilized in research settings to study adrenal responses and the effects of corticosteroids. Its synthetic nature ensures consistent and reliable results compared to natural ACTH.