Ilana Katz MS, RD, CSSD
Hyponatremia tends to be mostly associated with athletes who participate in long duration sports such as marathons and triathlons. Endurance athletes taking in water during training or an event can develop hyponatremia, a potentially life threatening condition that occurs when sodium levels drop to a dangerous low in the blood stream (below 135 mmol/L (of blood). Early symptoms may include nausea, drowsiness, confusion, headache and fatigue. These can quickly progress to seizures, coma and death if not resolved in time. Importantly, athletes are not the only population that needs to be aware of this deadly phenomenon.
Dilution of sodium can result, as mentioned, from over-drinking, but also from water retention (often a side effect of various medications). Sodium can be lost in various ways other than dilution which include urination, perspiration and gastrointestinal distress (vomiting/diarrhea). Furthermore certain medical conditions such as congestive disease, kidney dysfunction and ineffective ant-diuretic hormones are known causes.
Since hyponatremia has usually been associated with endurance sports, those who engage are much more well-informed than in the past, and emergency staff who treat athletic stress conditions are also far better educated to recognize and manage symptoms, and even play a role in prevention. The sports medicine community has been helpful in raising awareness about risks and signs of over-hydration. However, with obvious evidence that there are many other populations at risk for hyponatremia, it is vital to recognize these so that all health care professionals are on the leading edge of avoidance and if necessary, acute care.
Some examples of patients who may be eligible for high alert:
- Psychiatric patients with a syndrome known as psychogenic polydipsia, meaning they drink excessive amounts of water..
- Multi-pharmocological patients (especially elderly). Why, well because many medications have potential risks.
- Diuretics deplete electrolytes, including sodium
- Antidepressants increase level of antidiuretic hormone
- Patients being administered intravenous hypotonic fluids: hypotonic fluids contain a lower concentration of sodium than blood and thus excessive quantities at high entry rate can dilute sodium.
- Tube fed patients: proper fluid levels and electrolyte balance must be continuously monitored and orders adjusted based on results of consistent blood work.
There is also the all controversial sodium debate to consider. Researchers and health practitioners often have opposing arguments as to whether dietary sodium should always be strictly conserved. While lowering sodium is unarguably beneficial for those already diagnosed with hypertension (high blood pressure), increasingly conservative recommendations for the average population is often contested. The argument being that too little sodium can lead to other health problems, the main one being hyponatremia. Interestingly, the dietetic community are in agreement that avoidance of dietary sodium is unlikely to cause hyponatremia. Even a very low sodium diet of 500 – 1000 mg/day should maintain adequate levels under normal circumstances. It is the complexity of what defines “normal circumstances.”
In summary, with regards to controlling appropriate levels of sodium in the blood and avoidance of hyponatremia, not only athletes should be aware of hyponatremic signs and symptoms. For those with a normal blood pressure, eating patterns and water intake should be developed based on clinical judgement, guidelines and scientific evidence.
I’ve been dealing with a heart condition (PSVT) that is aggravated by high levels of sodium in my diet.
As I’ve cut down on my sodium intake, I’ve been surprised recently to see just how little sodium I actually need to continue to perform.
When I noted the correlation between high sodium, particularly in the evening, and PSVT episodes the following morning (I have been keeping a detailed food log since last April, and 5 straight trips to Fellinis on Ponce eating the exact same item — with 1700mg of sodium — resulted in PSVT episodes the following morning), I cut down from about 5-7,000 mg daily Na down to about 3-4,000 in the summer.
3,000 in the winter still gave me episodes, but 1,500-1,800 mg daily kept them in check.
But the most telling was in October, after about 14 hours of inline skating (8 hours overnight to get to the starting line of Athens to Atlanta, 45 minute break, then 5.5 hours hard skating in the actual race.)
I was concerned about too much sodium during the 45 minute break resulting in a PSVT episode starting,
so I didn’t do my usual high Na beverages of Gatorade and Chocolate Milk.
Overall, I think my total Na during the 14 hours was about 5,000 mg, way, way lower than what I had accepted as the expected Na loss for 14 hours of sweating, which would have been about 14,000 mg (at 1 quart an hour, and 1,000mg per quart).
And shortly after I finished the race, the event winner came up to me, saw my clean, unsalted face, and commented, “look at you, all cleaned up after the race!”
But I had NOT cleaned up at all. I just lacked the salt streaks and salt coating that all the other skaters had by the finish. So at that point I realized that the low sodium didn’t detract from my performance (my 5:37 was my fastest ever “return” trip after going there and back, by about 25 minutes), and the salt streaks only show up when you have the standard, high sodium American diet.
That one event ended my concern about hyponatremia, which really was a concern since one of my friends had to give up skating Athens to Atlanta about 10 years ago, after his hyponatremia episode kept him from finishing after 72 miles, and sent him to the hospital to be placed in a coma for 5 days while he recovered.
It’s really tough to keep sodium levels that low, but the PSVT episodes are a pain in the butt, so I do it most days.
And if I want to eat my usual at Fellinis after our group’s night skates Monday or Wednesday, I can still do it, BUT I have to then do an extra hour of skating after, hard, to sweat enough to lower my sodium levels below the point where they facilitate the electrical issues of the PSVT problem.