Let's Discuss Blood in the Urine

In medical school and residency, we are not taught that there is a specific amount of water everyone should drink each day.  Like most things, fluid intake is relative based on a multitude of personal physical characteristics and medical history.  Nonetheless, when addressing water intake, my general rule and recommendation for patients is to consume enough water each day to maintain light, straw-colored urine. 

Everyone following and reading the Motion Expert blogs has had shades of urine that range from orange to clear.  Notably, there is also a substantial subset of you who have experienced red or brown urine, particularly following strenuous workouts.  More than likely, this caused some alarm and perhaps even some mental distress.  If you have, or have had, what you think is red or brown urine, your physician should know about it.  Reassuringly however, if it has occurred following a long, challenging run or workout, it is likely harmless and is not a sign of bad things to come. 

Instances of red or brown urine are not uncommon in long-distance runners, regardless of training.  Two main causes should be called out.

The first is exercise-induced hematuria, or “runner’s bladder.”  Hematuria is the medical term for blood in the urine.  Exercise-induced hematuria is usually painless – though some folks may have some discomfort – and is otherwise not well understood in terms of its specific cause.  Either way, it appears to be benign (meaning not worrisome), usually resolves on its own within a few days to a week, and does not require further diagnostic testing.  The take-home message for this one is not to worry or fear.  Additional evaluation is warranted if the blood persists beyond several days (certainly a week), if there are clots of blood, if you are a male over 50, if you are known to be at increased risk for kidney or bladder cancer, or if this is a frequently recurring issue.

The second main cause of red or brown urine following strenuous exercise is myoglobinuria, which is the medical term for muscle tissue protein in the urine.  This occurs when there is considerable muscle stress and breakdown – a term called rhabdomyolysis.  Heat, humidity, and low potassium can all contribute.  With myoglobinuria, the urine is usually more brown than red, and pain, weakness, swelling, and fatigue can be present.  If this occurs and you have significant pain or discomfort, emergent medical attention is advised.  For everyone else, aggressive hydration and rest are recommended to avoid further damage to the muscles or kidneys. 

Whether your urine is red or brown, it should put you on notice to pause and take a step back – you could be overdoing it.  Your health care provider should be aware that this has happened – particularly if this is the first time – but it’s likely not an emergent or urgent issue.  The issue should resolve on its own within the next couple of days.  Take that time to listen to your body and to ensure that you are adequately resting and hydrating. 

Your water intake should be proactive and strategically reactive based on your running patterns, especially in the summer.  Your urine color will tell you when enough is enough. 

This article originally appeared in the TCM's weekly e-newsletter, The Connection. Subscribe to the Connection here.

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Kenneth G Poole, Jr, MD, is an internal medicine physician with a special interest in running. He is one of the team of Motion Experts TCM has gathered to help its subscribers and participants get the most out of their running. Instagram: @renaissance_doc; X: @KPooleMD