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What Does It Mean When You Have Protein In The Urine?

Author: Pedro Cortes, M.D., Director, Nephrology Research Laboratory, Henry Ford Hospital, Detroit, MI
Source: Diabetes Explorer, May/June 2006

 What does it mean when you have protein in the urine?

Urine is essentially filtered blood. It is the result of blood pressed (by blood pressure) through a very good filter, one’s kidneys. In this process blood cells and blood proteins are retained in the circulation while fluid containing waste prodcts of small size pass through this filter and into the urine. A defective filter with holes larger than normal will allow blood products of large size to escape into the urine. The most abundant of these escaping products is protein. Thus protein in the urine means a damaged urine filter, which often is the first evidence of kidney disease.

How to test to see if you have kidney damage?

The most sensitive test to detect early kidney damage is to measure the amount of albumin (a normal blood protein) in the urine. Since at the beginning this amount is very small, it requires special methods of detection. At later periods, when the disease is well established, the presence of albumin in the urine is in much greater amounts. Then, simple methods (dip-stick) can detect it.


Normal Less than 30 pg/mg creatinine
Microalbuminuria 30-299 pg/mg creatinine
Macroalbuminuria 300 pg/mg creatinine or greater