Long distance runners beware of hyponatremia

As physicians, if we know that our patients plan marathon running (or longer), we have a responsibility to warn them about fluid intake.  Alex Hutchinson writes regularly about the science of running in a column called Sweat Science.  Today his publication – How to Avoid Overdrinking: Researchers release new guidelines on preventing and treating hyponatremia. appeared on the Runner’s World website. I have had a great interest in teaching about hyponatremia for many years. In my standard lecture I mention the problem of hyponatremia occurring in long distance runners. Alex writes about the new guidelines concerning fluid intake: Most of the statements and recommendations are fairly unsurprising. Exercise-associated hyponatremia happens when you drink too much and levels of sodium in your body get diluted, most often in endurance events. The risk profile suggests that smaller and slower runners are particularly at risk. If you’re running more slowly, you’ll sweat less (even if your relative effort, i.e. as a percentage of VO2max, is the same), it will be physically easier to drink, and you’ll be out there longer, giving the effects more time to accumulate. One of the open questions is whether there’s some abnormal response that determines who gets sick from overdrinking. In most cases, we’re pretty good at peeing out extra water. Do the people who end up with hyponatremia have some malfunction of that fluid regulation process, or is it pur...
Source: DB's Medical Rants - Category: Internal Medicine Authors: Tags: Medical Rants Source Type: blogs