Protein in urine: What does it mean?

Our son just had his sports physical. His doctor said he had elevated levels of protein in his urine. Should we be concerned?

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Mayo Clinic urologist Erik Castle, M.D., and colleagues answer select questions from readers.

Answer

Small increases in urine protein are rarely a cause for concern. Typically, if a urine test shows a slight increase in protein, the doctor asks for a second urine sample. For the second sample, the doctor may request morning urine, which usually contains the least amount of protein. The doctor may also recommend a 24-hour urine sample, in which all urine from one morning to the following morning is collected, to quantify its protein content. During the 24-hour urine collection, it's important that your son strictly limit his physical activity.

Large amounts of protein in the urine may indicate a serious kidney problem. Normally, the body is very efficient in minimizing the amount of protein loss in the urine.

If a urine test shows a high level of protein loss in the urine, a doctor may recommend other tests — such as a urine analysis and a measurement of serum creatinine and creatinine clearance — to check kidney function. If you have concerns about your son's test results, ask his doctor for more information.