Which endocrine disorder is associated with hyperkalemia?

The association between Addison's disease and hyperkalemia is primarily due to the deficiency of adrenal hormones, specifically cortisol and aldosterone. In Addison's disease, the adrenal glands are not producing enough hormones, which leads to an inability to regulate electrolyte balance effectively. Aldosterone typically promotes the retention of sodium and the excretion of potassium in the kidneys. When aldosterone is deficient, as in Addison's disease, the result is poor sodium retention and impaired potassium excretion, leading to elevated levels of potassium in the bloodstream, known as hyperkalemia.

In contrast, the other disorders listed do not primarily lead to hyperkalemia. For example, Cushing's syndrome is characterized by excess cortisol, which actually can lead to hypokalemia due to increased aldosterone-like effects. Diabetes mellitus primarily influences blood glucose levels, and while it can have various related electrolyte disturbances, it is not typically associated with hyperkalemia in the context of its primary pathology. Pheochromocytoma involves increased production of catecholamines and does not have a direct link to hyperkalemia as part of its clinical features. Thus, Addison's disease is the most relevant endocrine disorder associated with hyperkalemia due to its specific hormonal imbalances.