I am a triathlete, and after a particularly tough workout recently I found my urine had turned pink. My GP didn't seem to know anything about it. Can you tell me if it's serious, or what?
(Jim Bledsoe replies:)
You're not the only one. Here are three examples from my own experience.
On a sunny summer day, a tennis player completes three strenuous sets of play and then rushes to the lavatory to do a pee. To his extreme consternation, he notices that he is filling up the urinal with something resembling pink lemonade.
A runner finishes a marathon and steps immediately into the loo to relieve himself. Like the tennis player, he is horrified to find himself spraying reddish liquid into the waiting receptacle.
A rower completes a two-hour workout during which she sweats heavily and fails to take in adequate quantities of sports drink. For the next 48 hours, she is literally 'seeing red' whenever she goes to the lavatory.
So what's going on? I can hear you asking. Well, a recent study found that up to 95% of athletes produce urine with unusual characteristics following hard workouts, and individuals engaged in strenuous exercise frequently find that their urine is coming up pink, or even bright red, after training sessions are over. These reddish tints to the urine indicate the presence of a condition called 'haematuria', which literally means blood in the urine.
What's actually in the urine, of course, is not whole blood but either red blood cells or haemoglobin, the colouring (and oxygen-carrying) pigment found in red blood cells. The deeper the colour of the urine, the greater the severity of the problem. Having pink pee means that you have a small quantity of red blood cells or haemoglobin present; shoot out red liquid, and there must be many red blood cells or much haemoglobin in the urine. In most cases, the red cells and haemoglobin are being filtered into the blood via the kidneys, but the bladder may also be letting blood ease into the urine.
'Haematuria is linked with abrupt increases in the duration or intensity of training'
For unknown reasons, males are more likely to suffer from haematuria than females, and the risk of developing the disorder seems to increase after the age of 50. Haematuria is linked with abrupt increases in the duration or intensity of training, and strenuous exercise is in general 'riskier' than light exertion when it comes to passing pink pee. For example, in a recent study carried out at the School of Kinesiology at Lakehead University in Ontario, Canada, researchers found that about 14% of endurance runners exhibited exercise-related haematuria ('The Effect of Exercise Intensity on Haematuria in Healthy Male Runners,' European Journal of Applied Physiol Occup Physiol, 79(1), pp. 99-105, 1998). The haematuria-prone runners were then asked to try four different exercise protocols: (1) a 60-minute treadmill run at 90% of lactate threshold, (2) a 60-minute cycle ergometer ride at 90% of lactate threshold, (3) three 400-metre sprint running intervals, with four minutes of rest or light walking for recovery, and (4) three 60-second, maximal cycle-ergometry tests, also with four minutes of recovery. Interestingly enough, the very short but very intense 400-metre sprints at maximal effort produced the most haematuria and also proteinuria (protein in the blood). Haematuria also tended to be greater after running, compared to biking, indicating that something unique to running could raise the risk of the disorder.
What is the cause of it?
There is debate about the root cause of exercise-linked haematuria, with the proposed mechanisms including foot-strike haemolysis (breaking down of red blood cells as a result of the impacts of the feet with the ground during sporting activity), renal ischaemia (lack of adequate blood flow to the kidneys), hypoxic damage, the release of a haemolyzing factor during exercise, bladder and/or kidney trauma associated with exertion, the use of non-steroidal anti-inflammatory drugs, dehydration, and the peroxidation of red blood cells which is an inevitable feature of sustained aerobic exercise ('Sport-Related Haematuria: A Review,' Clinical Journal of Sport Medicine, Volume 7(2), pp. 119-125, 1997).
Researchers in the Department of Urology at the Golda Medical Center in Israel suggest that there is a key mechanism by which non-traumatic exercise-related haematuria usually develops (they note that traumatic haematuria can be caused by a blow to the kidney area or by bladder injury due to repeated impact of the posterior bladder wall against the bladder base during continuous exercise, which can cause vascular lesions): during continuous exercise, vasoconstriction of the splanchnic and renal arteries and arterioles occurs so that blood can be redistributed to the contracting skeletal muscles and skin. The resulting, reduced flow of blood and oxygen to the kidney's filtering units alters kidney function and allows more materials, including red blood cells and haemoglobin, to pass out of the blood into the urine ('Sports Haematuria,' Journal of Urology, vol. 143 (5), pp. 887-890, 1990).
'Haematuria has few other symptoms, though burning during urination, pain in the genitals, abdominal discomfort and low-back pain have sometimes been reported'
Note that dehydration makes this haematuria-producing mechanism much worse. For example, when you exercise strenuously for extended periods, particularly on warm days, you often suffer a significant net water loss as a result of sweating and expelling moist air from your lungs, even when you are drinking replacement fluids. Blood volume then dips, and blood flow to the kidneys is restricted even more than usual, magnifying the 'spill-over' effect described above.
Aside from reddish urine, haematuria has few other symptoms, although burning during urination, pain in the genitals, abdominal discomfort, and low-back pain have sometimes been reported in association with exercise-induced haematuria. The red-tinged urine normally reverts back to its straw-coloured appearance in 24 to 48 hours.
What to do about it
If you experience haematuria yourself, your doctor will want to take a complete personal and family medical history and will be concerned as to whether kidney disease is part of your family history. A urine sample will be taken and examined for the presence of red blood cells, white blood cells, and certain protein substances - to rule out or confirm bladder infection or kidney inflammation. If you're female, your doctor will want to know whether appearance of blood in the urine has been associated with menstrual blood flow, and in certain cases, your health-care professional will order blood tests and x-rays (or other imaging procedures) of your lower abdominal area.
Usually, the treatment for haematuria is a modification of exercise habits. Some individuals may need to back off on their training intensity and/or duration for a while, with a gradual return to the level of exertion originally associated with haematuria. This may actually work to limit the risk of haematuria if the athlete becomes fitter during the intervening period; one of the adaptations associated with fitness is an increase in plasma volume, which in effect helps to thwart the exercise-related renal-ischaemia problem. Naturally, you should never train or compete when haematuria is actually present.
Since dehydration is a key risk factor for haematuria, it makes sense to take in plentiful quantities of fluid during workouts and competitions; during a workout or race lasting for an hour or more, it's reasonable to swill 10 ounces of sports drink 10 minutes before the start of exertion and then about five regular swallows every 15 minutes during the overall effort. During soccer, rugby, tennis, and basketball practices and matches, one should attempt to drink extensively during break periods and time-outs (as part of this strategy, it's important to keep palatable drinks close at hand so that they may easily be taken in). Caffeinated drinks such as coffee, tea, and cola should be avoided by haematuria-prone athletes, since such beverages can increase the chance of dehydration.
'Weigh yourself in the nude before and after your practices... and also measure how much fluid you ingest'
A very sensible way to lower your risk of dehydration is to determine your typical 'fluid shortfall' during exercise. To do this, weigh yourself in the nude before and after your practices (you'll be sweaty after practice, so dry yourself off with a towel before weighing) and also measure how much fluid you ingest. For each pound of weight you lose during the exercise period, your fluid shortfall is about 16 ounces. For example, if you lose three pounds during a two-hour training session, you have sweated away 48 ounces more fluid than you have consumed. During future training sessions, you should gradually increase your fluid intake - even if you don't feel thirsty - until you can replace at least 75% of your sweat losses during exercise. In the example just given, you would need to increase your drinking by at least 0.75 x 48 = 36 ounces per two-hour workout (remember that this is above and beyond what you originally drank). It sometimes helps to use an alarm wristwatch to remind you that it's time to take a drink.
The bottom line? Haematuria itself is usually a fairly benign condition, but it should be evaluated by a health professional, since it can sometimes indicate underlying problems such as kidney or bladder infection or even cancer. If you engage in contact sports (football, rugby, boxing, etc), you should make sure your haematuria is not the result of physical trauma to your urinary system.
Even if serious health problems do not exist, however, haematuria in an athlete is an indication that something has gone awry. If the haematuria is caused by dehydration, the athlete should correct the dehydration in order not just to stop the production of pink urine but to perform at a higher level. If the haematuria results from overexertion, the athlete should train more suitably for his/her level of fitness. Note, too, that chronic haematuria can eventually lead to anemia. Thus, athletes suffering from haematuria should not ignore the condition or plead that a little urinary bleeding is 'normal'; they need to eliminate the pink pee. By doing so, they will be able to ultimately achieve higher levels of fitness.