DEAR DR. DONOHUE: I have been diagnosed with inappropriate antidiuretic hormone and have been told to restrict my fluid intake to 1.5 liters (1.59 quarts) per day. What causes this syndrome? What are the short- and long-term consequences? Do I count foods prepared with liquids, such as oatmeal? - G.H.
ANSWER: Most people have never heard of antidiuretic hormone, also called vasopressin or arginine vasopressin. It comes from the pituitary gland at the base of the brain. It preserves body-fluid balance by regulating urine volume. If the body is low on fluids, ADH secretion diminishes urine production, and body fluid levels rise. If the body has too much fluid, ADH production drops off, urine output increases and body fluid levels drop.
Inappropriate ADH is the situation where the body has more than enough fluid, but ADH secretion continues, and body fluid reaches high levels. Urine production has been shut down. The expansion of body water dilutes the blood sodium concentration. Low sodium leads to headache, confusion, loss of appetite, nausea, vomiting and, in extreme cases, coma. With proper treatment, long-term consequences are minimal and few.
Causes of the syndrome include lung, ovary and pancreatic cancer; multiple sclerosis; neuropathy; some medicines; infections such as pneumonia, tuberculosis and meningitis; strokes; congestive heart failure; and severe digestive-tract inflammation. These are common illnesses, making inappropriate ADH common. As with all illness, sometimes a cause cannot be found.
A reduction of fluid intake is the first step in treatment. If you're not making progress, shown by a rise in blood sodium, then you have to adopt stricter fluid restriction. Measure you urine output for 24 hours. Your intake should be 500 ml (16.9 ounces, about 2 cups) less than that amount. Even the most solid of solid food has fluid in it. You don't have to consider that amount of fluid or the fluid in a stew. You should in foods like soups.
If fluid restriction isn't improving the blood sodium level, medicines can be used. Demeclocycline is one. Tolvaptan is another. Most importantly, treatment of the underlying cause is the best approach, if an underlying cause has been found.
DEAR DR. DONOHUE: What benefits do Epsom salts offer? Secondly, we occasionally enjoy a glass of wine with our meals. The label states that the wine contains sulfites. What are they? Are they harmful? - J.R.
ANSWER: Epsom salts are magnesium sulfate. Around 1695, in the area of Epsom, England, deposits of these salts became a popular remedy for sore muscles and joints. Nowadays, most doctors believe the warm water of a soak is as effective without the salts as with them.
Sulfites are preservatives found in many foods and drinks. They prevent spoilage. Unless you're allergic to sulfites, they are not harmful.
- Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible.