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. 

eAJKD: Test your knowledge on Glomerular Diseases in Sjorgen's syndrome

Check out the latest post on eAJKD re SS and Glomerular Diseases.

CONSULT ROUNDS: Sjogren's Syndrome and Glomerular Diseases?

What is the association of Sjogren's Syndrome(SS) with any glomerular disease..

Well, besides few cases reports scattered in the literature, there are two large case series that highlight this nicely.

In 2001, Bossini et al described the clinical and morphological features of kidney involvement in SS.  Sixteen patients (27%) had laboratory evidence of tubular and/or glomerular dysfunction.  Renal biopsies from nine patients showed tubulo‐interstitial nephritis in six and glomerular disease in three. The three diagnosis were MPGN, mesangiproliferative and membranous. Patients with renal involvement had a significantly shorter disease duration compared with patients without renal abnormalities.

A more recent study in CJASN looked at more number of patients and at least 24 biopsies of SS patients showing mostly tubular interstitial disease but the glomerular disease was a mixed bag: FSGS, mild mesangial sclerosis, MPGN, minimal change disease( 1 case), membranous, were the ones reported. The paper is free access ( look below). Four patients (17%) were diagnosed with lymphoma during their follow-up. Below is a pie chart from the paper that had 24 cases and the distribution on the biopsy. Overall, not a very common thing to see in SS, but glomerular disease is likely.

From CJASN 2009

http://ndt.oxfordjournals.org/content/16/12/2328.full

http://cjasn.asnjournals.org/content/4/9/1423.full