Which electrolyte disturbance is commonly associated with Cushings disease due to sodium retention?

• A. Hyperkalemia
• B. Hyponatremia
• C. Hypernatremia
• D. Hypocalcemia

Answer: (C)

Excess cortisol in Cushing disease acts like a mineralocorticoid in the kidneys, promoting sodium reabsorption in the distal tubules and water retention. This sodium retention expands the extracellular fluid and elevates the serum sodium concentration, producing hypernatremia. While potassium may be lost due to the same mechanism, the key electrolyte disturbance linked to sodium retention is hypernatremia. Hyponatremia wouldn’t fit the typical pattern of cortisol excess.