Why Do I Have Blood in My Urine After Running?

Q Is it normal to have blood in the urine after running? This happened to me last year (during a 10km run, which was a normal distance for me). I had a whole series of tests afterwards, which were all normal and the urologist said it was common for runners. But, is it common? This happened again recently after another 10km run over the weekend and a 5km run this morning. My base runs are 5km 4-5 days a week with a long run the weekend. Is it normal for runners? – ANNE


A Blood in the urine is not normal, but does happen occasionally in some runners. There are two types of hematuria (blood in the urine) – macroscopic where you can see it and microscopic where we see it under a microscope. The usual causes of hematuria are infection, trauma, kidney stones, cancer, blood cell disorders, medications and strenuous exercise. We do not know why strenuous exercise can cause blood leaking in the urinary tract, but it could have to do with fluid balance (dehydration), blood cell breakdown, or bladder trauma.

You did the right thing by getting evaluated after the first episode. I am guessing that you had a study of your kidneys like an ultrasound and a cystoscopy where the urologist could directly visualise your bladder. If those two tests and others for abnormal blood cells are normal, and you did not have an infection, you likely have a running-induced blood leak. It is important to have all the causes, especially bladder cancer, ruled out before you assume the blood loss is due to exercise. Exercise-related hematuria is a diagnosis of exclusion.

If the leak is in the bladder, there may be a strategy to reduce the problem. Some runners get blood loss if they void immediately before the run, and the hypothesis is that the bladder walls slap together causing traumatic blood loss. The usual recommendation to relieve this form of hematuria is to void 20-30 minutes before your run so there is some urine in the bladder to “soften” the slap. – BILL

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