Which laboratory value is elevated in Addison's disease?

In Addison's disease, which is characterized by adrenal insufficiency, the adrenal glands do not produce enough corticosteroids, particularly cortisol and aldosterone. Among the laboratory values associated with this condition, serum potassium levels are often elevated. This occurs because the lack of aldosterone, which normally promotes sodium retention and potassium excretion in the kidneys, leads to an accumulation of potassium in the blood.

Patients with Addison's disease frequently exhibit hyperkalemia (high potassium levels), which can result in various symptoms such as muscle weakness, fatigue, and heart rhythm disturbances. The elevation in serum potassium is a critical indicator of the adrenal insufficiency that defines Addison's disease, making it an important laboratory value for diagnosis and management.

In contrast, cortisol levels are typically low in Addison's disease due to the inadequate adrenal response. Aldosterone levels also tend to be low due to the disease process affecting the adrenal glands. Calcitonin, produced by the thyroid gland, is not directly related to Addison's disease and does not demonstrate changes associated with this adrenal condition. Thus, when considering the elevated laboratory values in the context of Addison's disease, serum potassium is the correct answer.