Cosyntropin is a synthetic polypeptide analog of adrenocorticotropic hormone (ACTH) primarily used in medical diagnostics to assess the function of the adrenal glands. It is administered to stimulate the production of cortisol, a hormone essential for stress response, metabolism, and immune function. By measuring cortisol levels before and after administration (via the ACTH stimulation test), healthcare providers can diagnose conditions such as adrenal insufficiency or Addison's disease. Its synthetic nature ensures consistency, purity, and reduces the risk of allergic reactions compared to natural ACTH preparations.