Dear Dr. Roach: Two weeks ago, my sodium was too low. I was told to drink more water and increase my sodium. I always put salt on my food. I eat ramen noodles and drink the broth, so I don鈥檛 understand how it can be low. Both my feet are so swollen that I can hardly get my shoes on, but they tell me to keep my feet up. I also get headaches and feel nauseated at times.
Could you please talk about low sodium and what causes it? I am taking HCTZ for blood pressure.
J.U.H.
Hyponatremia, a low sodium level in the blood, rarely is about getting too little dietary sodium. Instead, it is about the inability of the body to handle free water. Occasionally, this is because people drink excessive amounts of water, but far more frequently it is because the body is producing too much anti-diuretic hormone for the situation. However, in your case, the cause likely is the HCTZ.
Hydrochlorothiazide prevents the kidneys from being able to dilute urine appropriately, so the sodium level in the blood goes down if you drink a lot of water. The advice about drinking a certain number of glasses of water a day doesn鈥檛 apply to everybody. You shouldn鈥檛 be trying to drink extra water; in fact, you should be cutting back a little bit.
That does NOT mean that all people on diuretics need to be careful about drinking too much water. In hot weather, people need extra water. Drinking when you are thirsty is a good idea, and drinking extra if you haven鈥檛 needed to urinate in a while is another.
Swollen feet might indicate problems with the kidney, heart or liver, so have your doctor make sure nothing is wrong there.
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Dear Dr. Roach: Is it OK to reuse bottled water bottles for water from a new gallon container of drinking water and tap water?
S.K.
Reusing water bottles is a great idea, since it helps the environment. There is no medical reason not to. I have a steel flask that I like to use because it keeps the water cold. I also drink only tap water, being in a fortunate area with outstanding-quality water.
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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to [email protected].
