Athlete with Protein in Urine

My son is an otherwise healthy 18 year old. He is a cross country runner, running 8-10 miles seven days a week. He was just pre-screeded prior to attending college and running cross country for their team. He was given a routine CBC and urinalysis
required by the school athletic department. The CBC was normal, but the urinalysis showed protein in the urine. I do not have more specifics. His doctor seems to think it is from dehydration and not eating enough. He is 5'9" and now weighs 134lbs., he has always had trouble maintaining a decent weight during the season.
The doctor has ordered no running for three days, and then a retest. This problem has potentially large consequences, not only not running but maybe not getting off to college at all. Can you provide any insight on this issue and any specific ideas as to how to remedy this. Obviously we are both very concerned about this. Thank-you.

[Kevin Pho, MD]

Hello - thanks for asking your question.

As you can imagine, there are many causes of protein in the urine.  This should definitely be evaluated by your physician.

The first thing I would do is repeat the test after a few days of not exercising (as you are doing).  Transient proteinuria is the most common cause (occuring in 4 percent in males and 7 percent in females) - simple infection, dehydration or exercise can cause protein in the urine.  If the protein resolves on repeat, then some sort of transient cause (such as exercise) is the most probable cause.

If the proteinuria persists on retest, then further evaluation - possibly with a kidney specialist - may be necessary.  Causes for persistent proteinuria would include various forms of kidney diseases.  I would hold off on a more extensive evaluation until the urine tests are repeated.  

Followup with your personal physician is essential.

This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.

Thanks,
Kevin, M.D.