Dear Dr. Roach: My husband had a nonstop coughing incident for a night and day after a feast, which landed him in the emergency room. He was found to have extremely low sodium levels (118-120 mEq/L), confusion, and a lot of heartburn. They are treating him for the low sodium by holding back his water consumption, but we are concerned that no one is looking into the underlying condition. Any suggestions?

— M.C.

Answer: I think your husband has the syndrome of inappropriate antidiuretic hormone (SIADH). Antidiuretic hormone (ADH), also called vasopressin or arginine vasopressin, helps regulate water in the body. When the body makes too much ADH, the urine is concentrated because the body cannot excrete water. Too much water means too little sodium in the blood.

Very low sodium levels can cause confusion, and in severe cases, seizures and even comas can occur. Free water restriction is the primary treatment, although sometimes sodium is necessary. The sodium level has to slowly return to normal, or the brain can suffer a severe shock, causing a dangerous condition called demyelination of the brain.

Your question of the underlying condition is the right one, and although sometimes we can’t find one, the coughing incident suggests that he might not have swallowed all of his feast correctly. Aspiration of food into the lung causes lung damage, which is a well-known trigger of SIADH. Other triggers include brain issues, like a stroke; some lung tumors; hormone deficiencies (thyroid and cortisone); and certain drugs.

Many experts will get a CT scan of the chest and brain as well as some hormone levels to look for the most common causes of SIADH. In the case of your husband and his severe cough, I think the lungs are the most likely culprit if one can be found.

Dear Dr. Roach: I am a 25-year-old woman. I was advised by my neurologist that my ferritin levels were on the low end and that I should consult with my primary care physician. I have a previous ferritin test from 2023 where my ferritin level was about 40 ng/mL. I was advised to use iron supplements but have stopped since July 2024. Could you please share any advice you have around supplementing iron in bioavailable forms?

— V.B.

Answer: Menstruating women always lose iron, so they have to take in at least as much as they lose or they will gradually get iron-deficient. Women with heavier periods often have difficulty keeping up, especially if they don’t eat a lot of meat.

Oral iron supplementation often causes symptoms, especially constipation. But taking a supplement once every other day gives almost as much benefit as once a day or multiple times a day with far less annoying side effects.

Another helpful tip is that vitamin C helps iron absorption. It doesn’t need to be a lot, like a glass of citrus fruit juice or a small vitamin C supplement. (Eighty milligrams is almost as effective as 500 mg.) It may also help to know that coffee reduces iron absorption, while cooking with cast iron does increase iron levels somewhat.

Although there are many types of iron supplements, they all work well if you take them, and there is no convincing evidence that one has fewer side effects. So, I typically recommend the one with highest iron content supplement, which is 325 mg of ferrous sulfate every other day.

I have rarely prescribe IV iron replacement, but this is an option for people who can’t tolerate oral iron or in whom it isn’t enough.

Contact Dr. Roach at ToYourGoodHealth@med.cornell.edu.