Proximal RTA (type 2) treatment commonly includes which therapies?

• A. Thiazides and potassium-sparing diuretics
• B. High-dose bicarbonate alone
• C. ACE inhibitors
• D. Sodium phosphate supplementation

Answer: (A)

In proximal (type 2) RTA, the proximal tubule fails to reabsorb bicarbonate, causing bicarbonate wasting and a metabolic acidosis with potential potassium loss. The treatment goal is to correct the acidosis while reducing bicarbonate loss and balancing potassium. Thiazide diuretics help by producing mild volume depletion, which increases proximal bicarbonate reabsorption and lowers the amount of bicarbonate that must be given as therapy. At the same time, potassium-sparing diuretics counteract the tendency toward potassium loss that accompanies bicarbonate therapy and the distal nephron’s handling of sodium. Put together, this combination reduces the bicarbonate dose needed and helps maintain potassium, making it a common approach in proximal RTA. High-dose bicarbonate alone often isn’t sufficient, and ACE inhibitors aren’t part of standard therapy for this condition; phosphate supplementation addresses another aspect of Fanconi syndrome but isn’t the primary treatment for the bicarbonate-wasting issue.