Why is measuring ACTH levels clinically significant?

Measuring ACTH (adrenocorticotropic hormone) levels is clinically significant primarily because it aids in diagnosing adrenal dysfunction. The adrenal glands produce cortisol in response to ACTH, which is released by the pituitary gland. When there is an adrenal disorder, such as Addison's disease (adrenal insufficiency) or Cushing's syndrome (overproduction of cortisol), measuring ACTH levels can help differentiate between primary adrenal problems (where the adrenal glands are not functioning properly) and secondary causes (like pituitary tumors) that result in abnormal ACTH levels.

High levels of ACTH may indicate that the adrenal glands are not producing enough cortisol on their own (as seen in adrenal insufficiency), while low levels may suggest that the pituitary gland is not adequately stimulating the adrenal glands, indicating possible pituitary dysfunction. Thus, measuring ACTH levels is crucial in understanding adrenal health, guiding further testing and treatment strategies for patients presenting with signs and symptoms of endocrine disorders.