Which findings suggest type 2 renal tubular acidosis (RTA)?

Updated: Dec 08, 2020
  • Author: Christie P Thomas, MBBS, FRCP, FASN, FAHA; Chief Editor: Vecihi Batuman, MD, FASN  more...
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The diagnosis of type 2 RTA should be suspected in patients who have a normal-AG metabolic acidosis with a serum HCO3- level usually greater than 15 mEq/L and acidic urine (pH < 5.0). Those patients have an FEHCO3- less than 3% when their serum HCO3- is low. However, raising serum HCO3- above their lower threshold and closer to normal levels results in significant HCO3- wasting and an FEHCO3 exceeding 15%.

FEHCO3- = (urine [HCO3-] X plasma [creatinine] / plasma [HCO3-]) X urine [creatinine] X 100

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