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Kidney Diseases

Shrinking Kidney-Normal or Reason for Concern



I was to undergo an CT with contrast for pain I have been having in my right side for months, but the test was done without contrast due to abnormal BUN result of 4. CREAT W GFRE was normal. The CT showed that the right kidney measures 9.3cm compared to my previous CT done in 1994 when it measured 10.1cm. Is this reason for concern? I do have Sjogren`s and am wondering if that might be involved?


A BUN of 4 is not abnormal (did you make a typo?).  However, the normal size of kidneys on ultrasound is 10-13 cm, so your right one is on the small side and has gotten smaller in the last 15 years.  Shrinking of a kidney usually means that scar tissue has developed, replacing normal kidney tissue.  The most likely cause for this is decreased blood flow to the kidney because of hardening of the arteries.  Sjogren's does not usually cause kidneys to become scarred, unless there are kidney stones, which sometimes occur with this disease.  

People normally have quite a bit of reserve kidney function, and the fact that you still have a normal eGFR indicates that you have plenty of function (as far as being able to excrete waste products).  A small kidney due to narrowing of the artery can sometimes result in hypertension, so your blood pressure should be carefully monitored and treated if high.  It is unlikely that your right kidney is the cause of your right-sided pain, unless something else was abnormal about the kidney besides its small size.

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Response by:

Mildred   Lam, MD Mildred Lam, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University