Consult Rounds: Distal RTA and Sjorgren's Syndrome

Distal renal tubular acidosis in Sjorgren’s Syndrome (SS):

1. One of the mechanisms is an absence of the H-ATPase pump on intercalated cells in the collecting duct.  

2. Also, Sjogren's syndrome (SS) leads to autoantibodies directed against carbonic anhydrase II.

This leads to less proton excretion.

3. Severe hypokalemia might also suggest that there is a combined proximal and distal RTA.
4. Full blown fanconi syndrome has been described in SS as well.

5. Severe hypokalemia can occur in SS despite no RTA and is thought to be due to tubular damage induced sodium wasting with subsequent increased distal sodium delivery.  

6. Chronic hypokalemia can lead to a nephrogenic diabetes insipidus(NDI)

7. Regarding NDI, the largest series is an Italian series 21% of patients were noted to have an abnormal urinary concentrating ability. Lymphocytic infiltrates of the collecting duct might be the cause. 

8. A nice attending rounds in CJASN discusses hypokalemic metabolic acidosis.