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Kidney Diseases

What does an extremely elevated BUN mean?

06/23/2010

Question:

My husband had a creatinine of 3. today but a BUN of 109. He is extremely tired; has confusion more often and a history of Type 11 Diabetes; Heart Disease; PVD; Congestive Heart Failure. Does this extreme number suggest failure of his kidneys?

Answer:

A very high BUN sometimes means advanced kidney failure.  But in that case, the creatinine is usually very high as well; with a BUN of 109, I'd expect a creatinine of 9 or 10 (with renal failure alone). 

There are several conditions that can cause a BUN that is disproportionately higher than creatinine.  These include:

a) heart failure alone
b) heart failure treated with diuretics (water pills)
c) internal bleeding, especially in the stomach or intestines
d) high doses of steroid medications like prednisone

Please check with your husband's doctors to see if one of these scenarios may apply to him.  Advanced kidney failure can certainly cause tiredness and confusion; but so can heart failure and severe anemia (for instance, if there is internal bleeding).  He sounds like he has a very complicated illness -- best wishes for his improvement, and please write again if I can furnish any more information for you.

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Response by:

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