Addison's disease commonly presents with which electrolyte disturbance guiding fluid therapy?

• A. Hyperkalemia
• B. Hyponatremia
• C. Hypercalcemia
• D. Hypomagnesemia

Answer: (B)

In Addison's disease, lack of aldosterone leads to salt wasting by the kidneys, so sodium is lost in urine and circulating volume drops. Cortisol deficiency further raises ADH, promoting water retention and diluting serum sodium, making hyponatremia a common and clinically important finding. Because the priority in management is to restore intravascular volume and correct sodium loss, fluid therapy is guided by hyponatremia and typically uses isotonic saline to replenish both sodium and fluid, while starting glucocorticoid and mineralocorticoid replacement. Hyperkalemia can occur due to reduced potassium excretion, but this electrolyte issue is not the primary driver for the initial fluid management; hypercalcemia and hypomagnesemia are not the typical disturbances guiding therapy in this context.