In type 4 RTA, which electrolyte abnormality is typically present?

In type 4 RTA, which electrolyte abnormality is typically present?

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

Answer: (A)

In type 4 RTA, the key issue is reduced aldosterone effect—either due to hypoaldosteronism or aldosterone resistance. Aldosterone normally drives potassium secretion in the collecting ducts; when its action is blunted, potassium secretion falls and serum potassium rises. This creates hyperkalemia, which is the characteristic electrolyte finding of this RTA type and is often accompanied by a mild metabolic acidosis from impaired ammonium excretion. The other options don’t fit this pattern: hypokalemia would reflect excess potassium loss or low intake, hypernatremia is not a hallmark of this condition, and hypocalcemia is not a defining feature.

In type 4 RTA, the key issue is reduced aldosterone effect—either due to hypoaldosteronism or aldosterone resistance. Aldosterone normally drives potassium secretion in the collecting ducts; when its action is blunted, potassium secretion falls and serum potassium rises. This creates hyperkalemia, which is the characteristic electrolyte finding of this RTA type and is often accompanied by a mild metabolic acidosis from impaired ammonium excretion. The other options don’t fit this pattern: hypokalemia would reflect excess potassium loss or low intake, hypernatremia is not a hallmark of this condition, and hypocalcemia is not a defining feature.