Dear Dr. Roach: I am a 91-year-old man with swollen legs. I take 20 mg of furosemide and 20 mEq of Klor-Con daily. I understand that the Klor-Con is to replace the potassium loss caused by the former. I also understand that I should reduce my salt intake to the lowest amount possible. Because of my age and the poor condition of my taste buds, the loss of table salt is extremely difficult. I have started using a salt substitute called NoSalt, containing potassium rather than the bad sodium. Since the salt substitute is providing me with potassium, can I eliminate or lower my intake of Klor-Con? E.P.
Answer: Sodium and potassium are critically important minerals that need to be regulated precisely. The kidney is normally very good at it, but the furosemide you are taking forces the kidney to lose both sodium and potassium along with water. Prolonged use of furosemide can lead to abnormalities, especially in potassium levels.
Low potassium can cause muscle cramps and weakness, even muscle breakdown. However, high potassium is even more dangerous, as it can lead to a fatal heart rhythm. Potassium replacement needs to be properly managed, including regular blood testing.
Salt substitutes are essentially the same as the Klor-Con you are taking. The first ingredient in your salt substitute is potassium chloride, which is the active ingredient in Klor-Con. According to the nutrition label, 1/4 teaspoon of the salt substitute contains 650 mg of potassium. Twenty milliequivalents of Klor-Con contains 800 mg of potassium.
Potassium in food is usually given in milligrams, whereas potassium in medicines is usually prescribed in milliequivalents.
With the prescription Klor-Con, you are getting precisely the same amount every day. Unless you are meticulously careful, your intake of the salt substitute is likely to vary a bit one day to the next. For a person with healthy kidneys, its probably fine. Your kidneys can probably get rid of any excess potassium, provided you are staying within reasonable limits. Its people with kidney disease (or who are taking other medications that raise potassium, such as ACE inhibitors, angiotensin receptor blockers or potassium-sparing diuretics) who need to be very careful with salt substitutes.
I should note that treatment with diuretics like furosemide (Lasix) is not an effective long-term treatment for most people with swollen legs. The swelling is commonly due to vein problems in the legs. Diuretics may be needed for people with swollen legs due to liver, heart or kidney problems.
