How does secondary adrenal insufficiency differ from primary in terms of electrolyte abnormalities and management?

• A. Hyperkalemia is more pronounced in secondary.
• B. Secondary has less or no hyperkalemia because aldosterone is preserved; cortisol deficiency dominates; treat with glucocorticoid replacement; check for pituitary origin.
• C. Aldosterone deficiency is the main issue in secondary.
• D. No treatment difference from primary.

Answer: (B)

In secondary adrenal insufficiency, the problem is a lack of ACTH leading to cortisol deficiency, while the aldosterone system (driven mainly by the RAAS) remains intact. That means potassium balance is usually preserved because aldosterone, which promotes potassium excretion, is still produced. The electrolyte pattern is dominated by cortisol deficiency, which can cause hyponatremia through increased ADH and water retention, but hyperkalemia is not typical. Management focuses on replacing glucocorticoids (for cortisol) and identifying a pituitary origin, rather than replacing mineralocorticoids. This contrasts with primary adrenal insufficiency, where both cortisol and aldosterone are deficient, leading to hyperkalemia and requiring both glucocorticoid and mineralocorticoid replacement.