DEAR DR. ROACH: I have hereditary hemochromatosis (HH) and atrial fibrillation. My AFib burden seems to vary with my iron levels. My AFib went from 58% to less than 2% in two weeks after I had a phlebotomy recently. I can’t find anyone else who has had this experience. Am I the only one?

My last ferritin test from a few weeks ago was 96 ng/mL. About the same time, I stopped using my combined COPD inhaler because of side effects. — P.M.

ANSWER: HH is a disease of iron absorption where the body cannot regulate how much iron it takes in. Normally, the body stops absorbing iron if it doesn’t need it, but with HH, the body absorbs as much as possible all the time. The body has no normal way to get rid of iron, except when menstruating women lose some iron every month, but this isn’t always enough to counteract the amount they get from their diets.

The resulting iron buildup after decades can cause damage to many tissues, including the heart. This can increase the rate of many kinds of arrythmias, not just AFib, and about 11% of people with HH will have an arrythmia.

Removing iron via phlebotomy (literally bloodletting; a person usually donates the equivalent of a unit of blood as often as necessary to get the iron level into the low-normal range, about where yours is) prevents most organ damage from iron overload. However, it doesn’t do so quickly, and I don’t think your recent phlebotomy was the cause of the sudden drop in your AFib.

Rather, I think it was the inhaler. One of the components of a combination inhaler is a beta agonist, such as albuterol (or a similar but longer-acting drug). These open up the airways, but they also tend to make the heart beat faster. They also predispose people to rhythm disturbances such as AFib. AFib in some people is permanent, but it comes and goes in other people. AFib is highly irregular and can be fast-paced or normal (and rarely slow).

Many people with AFib have an underlying risk, such as a genetic predisposition. When combined with damage to the conduction system by iron deposition in the heart, or by a medication that can induce AFib in susceptible people (or both), then AFib becomes much more likely.

In your case, I think the inhaler made AFib much more likely. Not everyone with AFib needs to stop using their inhalers (never do so without talking to your doctor), but some people are very sensitive to inhaled beta agonists that trigger AFib.

DEAR DR. ROACH: Is it possible to overdose on vitamin D through sun exposure? — S.C.

ANSWER: Vitamin D toxicity is a very real thing, and it’s reasonable to be concerned about it. Since the skin can make large amounts of vitamin D, I understand why you are asking this question.

Fortunately, numerous studies have shown that even in people with very high amounts of sun exposure, the blood levels stay well below the toxic level. The body is smart and has mechanisms not to poison itself. (Hereditary hemochromatosis is one of the few examples where the body can poison itself by letting the gut absorb too much iron, as this is a failure of the regulatory system.) Vitamin D toxicity almost only ever occurs in people who are taking high doses of supplemental vitamin D.

Sun damage to the skin is a much bigger concern than vitamin D with prolonged sun exposure.