Running: Physiologically SpeakingWhy Am I Peeing Blood After My Long Run?

Oops, it happened again, today, to a running friend after she ran 12 miles. Something weird. Something unexpected. And yeah, it freaked the living daylights out of her.

The first time it happened to a friend, I was there, with F.L., when she came out of the bathroom right after the Boston Marathon. She was somewhat freaked as well.

In both circumstances, I happened to be at the right place at the right time and luckily, I miraculously did not fall asleep when they covered this topic in medical school. Go me! On the other hand, I wonder how much running-related medical information I must have missed out on because I used to sleep through all the lectures. Damn, if only I knew I’d be a runner way back when…

Lam, stay on topic, so what is thing that happened to F.L. and your running friend? They both started peeing blood right after their runs. I thought it was obvious from the post title.

Maybe that’s obvious. But why? They both had E.I.H.

What’s E.I.H.? Is that the name of a new designer steroid for performance enhancement? No, no, no. E.I.H. stands for exercise induced hematuria. It is the appearance of blood in the urine (gross or microscopic) occurring after a period of intense exercise in people who have no other evidence of kidney or urinary tract disease. It goes away with rest.

Are there any associated symptoms? No. The key feature of E.I.H. that separates it from everything else is that it occurs in the absence of any disease. As such it is completely asymptomatic, well aside from the residual muscle soreness as a result of the intense exercise of course.

How long does it usually last? It usually resolves within 24-48 hours.

What if it doesn’t? If the hematuria persists beyond 72 hours or you’re having other symptoms, such as pain or fever, then you’re not dealing with E.I.H. and should get checked out by a doctor. It could be a urinary tract infection that requires antibiotics or rhabdomyolysis that may lead to kidney failure or something else.

Why causes E.I.H.? No one really knows. One theory is that constant jarring of the bladder wall during exercise causes bleeding and leakage of blood into the urine. Another more physiologic theory is that when there is intense vasoconstriction of blood vessels into the kidney during prolonged exercise, some of the cells responsible for filtered the blood inside the kidney can die from ischemia and get filtered into the urine. Usually, this slight alteration in kidney function is reversible and not of any clinical consequence, but in cases where the kidneys are already artificially clamped down (as is the case after ibuprofen ingestion…hint, hint...) the effect can be multiplied and result in some degree of kidney ischemia and kidney failure.

How common is E.I.H.? Statistics vary, but according to some studies, about 20-30% of runners were found to have some degree of hematuria after a marathon. Most cases are microscopic though, which means they are not visible to the naked eye.

Is it preventable? Because no one knows what brings it on, no one knows how it can be prevented. There is general consensus though that dehydration plays a key role, so make sure you drink plenty of fluids before, during, and after your runs if you don’t want to see red in your pee.

Where can I go to learn more about this? You can read about it here and here. Someone also wrote a blog post about it here.

Hope you all learned something today. From now on, no more freaking out if you see a little blood in your pee after a long run, you hear? Good. Class dismissed.