A 45-year-old lady presents with diarrhea and hyperpigmentation alongside hypotension. What electrolyte abnormality is most likely?

The presentation of the 45-year-old lady includes diarrhea, hyperpigmentation, and hypotension, which suggests a clinical picture consistent with adrenal insufficiency, potentially Addison's disease. In adrenal insufficiency, particularly in primary adrenal insufficiency, electrolyte abnormalities are common due to a deficiency of glucocorticoids and mineralocorticoids.

The correct answer indicates a sodium level of 130 mmol/L and a potassium level of 6.2 mmol/L. In this scenario, the hyponatremia (low sodium) can occur due to inadequate aldosterone secretion, leading to sodium loss through the kidneys. Meanwhile, the hyperkalemia (high potassium) results from a lack of aldosterone, which is responsible for increasing the renal excretion of potassium. Since aldosterone levels are low in adrenal insufficiency, the kidneys retain more potassium, causing elevated serum potassium levels.

This combination of low sodium and high potassium specifically aligns with the symptoms presented, supporting the diagnosis of adrenal insufficiency. The hypotension further indicates a possible volume depletion due to inadequate sodium retention, while hyperpigmentation can also be attributed to the increased ACTH levels that occur due to low cortisol, stimulating melanocytes.

In contrast, the other choices present different sodium and