Which condition is primarily treated with mineralocorticoids?

Mineralocorticoids are primarily used to treat Addison's disease, a condition characterized by insufficient production of hormones from the adrenal glands, including cortisol and aldosterone. In Addison's disease, the lack of aldosterone leads to issues such as low blood pressure, electrolyte imbalances, and increased potassium levels. Mineralocorticoids, particularly fludrocortisone, are administered to help regulate sodium and potassium levels, promote sodium reabsorption in the kidneys, and manage blood pressure. This replacement therapy is crucial for restoring the balance of these electrolytes and alleviating symptoms associated with adrenal insufficiency.

Other conditions listed in the choices have different treatment focuses. Secondary adrenal insufficiency often requires glucocorticoid therapy rather than mineralocorticoids, Cushing's syndrome is treated by reducing cortisol levels typically through surgery or medication, and congenital adrenal hyperplasia involves replacing glucocorticoids and sometimes mineralocorticoids depending on the specific enzyme deficiency present. Thus, Addison's disease is the primary condition where mineralocorticoids play a central role in treatment.