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Kidney Diseases

One Kidney Smaller Why?



I had an ultrasound of my abdomen for abdominal pain. My left kidney was found to be less than half the size of my right. I am scheduled to see a specialist and am told there could be many reasons for this problem. What are some possible causes? I am 41 and in good health.


There certainly are a large number of reasons that one kidney is significantly smaller than the other in ‘healthy` 41 year olds! You could have been born with a small left kidney which otherwise can function well. One kidney can obviously do the job of two. Otherwise to donate a kidney would not be a wise move! Tests of kidney function of donors years later show no deficiency.

Another reason could be that the blood supply to the small kidney could have been slowly reduced by the process of atherosclerosis. This often is detected first by increase in the blood pressure. Cat scan and NMR studies will usually help in making the diagnosis. This is treatable with medication and or surgery.

Rarely blood born infectious agents may attack one kidney without any obvious ill feelings on the part of the patient. Blood and urine tests can be helpful in detecting the agent. Radiographic imaging such as an intravenous pyelogram, Cat scan and NMR are sometimes diagnostic.

There are autoimmune disorders that very rarely attack one kidney more than the other. Systemic Lupus Erythematosis, some forms of glomerulonephritis are two. Diabetes mellitus can affect one kidney more than the other.

A good site for more specific details on the web is the National Institute for Diabetes, Digestive and Kidney Diseases. I hope this information is helpful.

Related Resources:

national Institute for Diabetes, digestive and kidney Diseases

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Response by:

Philip W Hall, 3rd, MD Philip W Hall, 3rd, MD
Formerly, Professor Emeritus of Medicine
School of Medicine
Case Western Reserve University