When should type 4 renal tubular acidosis (RTA) be suspected?

Updated: Dec 08, 2020
  • Author: Christie P Thomas, MBBS, FRCP, FASN, FAHA; Chief Editor: Vecihi Batuman, MD, FASN  more...
  • Print

Type 4 RTA should be suspected in any patient with a mild non-AG metabolic acidosis and hyperkalemia. The serum HCO3- level is usually greater than 15 mEq/L, and the urine pH is less than 5.0 because these patients have a normal ability to secrete H+. The primary problem is hyperkalemia from aldosterone deficiency or end organ (collecting duct) resistance to the action of aldosterone. This can be diagnosed by measuring the transtubular potassium gradient (TTKG).

TTKG = urine K+ X serum osmolality/serum K+ X urine osmolality

Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!