Protein in the urine (known as proteinuria) is a finding in kidney disease. It is first necessary to find out exactly how much protein is spilling into the urine. If that protein loss is more than 3 grams per day, then he may have the nephrotic syndrome. If this is the case, a kidney biopsy is often required to make a specific diagnosis. I suggest consultation with a nephrologist to determine the amount of protein lost in the urine and if a kidney biopsy is warranted.
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