Dear Doctor: I started taking potassium pills about five years ago. Then after a few months, I began to have anxiety attacks so severe that I could barely talk to people. Finally, I read warnings about potassium's side effects, which included anxiety attacks. I immediately stopped taking the pills, but still have mild anxiety attacks. More people should know about this side effect.

Dear Reader: Thank you for sharing what has clearly been a difficult experience. Before we explore the potential risks, however, let's be clear on one point: Humans need potassium for normal cellular function within the body. Major deficiencies in this mineral can lead to severe muscle weakness, failure of the respiratory and gastrointestinal systems, kidney dysfunction, abnormal heart rhythms and possible death. Because many diuretic drugs deplete potassium, people taking such drugs should also take potassium supplements. So too should people with chronic diarrhea, for the same reason.

But if you're not taking medication that decreases potassium, don't have diarrhea and do have a healthy diet, you don't need extra potassium. That doesn't mean people don't take it, however. Some use potassium to ease muscle cramps or to help build muscle through workouts. Others use it as a table salt substitute. Some people even take extra potassium to reduce blood pressure, although there's no evidence that this has any effect.

Humans normally require 2,000 to 3,500 milligrams of potassium daily. Because the mineral is found in a variety of foods, most people's needs can be met through a generally healthy diet. Though it may be tempting to supplement, taking additional potassium can cause your levels to go too high. Because people with kidney dysfunction are already apt to have higher levels of potassium, taking supplements is especially risky for them.

An elevated potassium level can lead to muscle weakness and even paralysis. It can also interfere with electrical conduction in the heart, causing abnormal heart rhythms and, when severe, a shutdown of the heart's electrical activity, meaning loss of any muscle contraction and, quickly, death.

As for the kidneys, although they're efficient at maintaining potassium balance, they can be overwhelmed by high levels, causing them to retain more acid, which leads to metabolic acidosis. In this process, the body tries to decrease acidity in the blood by eliminating carbon dioxide via hyperventilation. (More on this later.)

In your case, I suspect that your potassium levels were too high to begin with. Angiotensin receptor blockers and ACE-inhibitors (both are blood pressure medications) can elevate potassium levels, as can the diuretic spironolactone. And, again, kidney dysfunction can elevate potassium levels as well.

As for your symptoms, it's possible that the high potassium levels led to an abnormal heart rhythm, which in turn led to panic. Another possibility is that the high potassium levels led to greater acidity in the blood -- and the ensuing hyperventilation.

That hyperventilation can lead to dizziness, nausea, palpitations, shortness of breath and chest pain -- many of the same symptoms as a panic attack.

I'm not sure if my line of thinking is correct, but I do agree that stopping the potassium supplement was the right thing to do. As a next step, I would also recommend that you see your doctor and have both your kidney function and your potassium checked. Those tests may provide some clarity.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: My son just got a job working construction in Houston, which means he's surrounded by noise pretty much all the time. A family friend says he read that all that noise might be bad for my son's health, including his heart. Just how strong is the connection between heart disease and noise pollution?

Dear Reader: When it comes to noise being bad for us, your friend is correct. Decades of research have suggested a strong connection between ongoing exposure to noise pollution and a host of adverse health outcomes. These range from feelings of annoyance and tension, to increasingly significant problems like sleep and anxiety disorders, depression and cognitive impairment, particularly in children. Now, after an analysis of years of existing data, researchers from Johannes Gutenberg University in Germany confirm what previous studies have suggested -- that hypertension and cardiovascular disease also belong on the list.

Inquiry into the physiological effects of noise dates back at least to the 1980s. Those earlier studies focused solely on the effects of traffic noise, including road sounds, horns and sirens. Later studies added the effects of aircraft and railway noise into the mix. Scientists found that exposure to noise pollution resulted in an increase of blood and saliva concentrations of cortisol, adrenaline and noradrenaline in the study subjects. Chronic high levels of these stress hormones are known to play a role not only in heart disease, but also in immunity, hypertension and stroke. Individuals appear to be particularly vulnerable to the ill-effects of noise pollution at night, during sleep.

In this most recent review paper, published earlier this year in the Journal of the American College of Cardiology, researchers connected seemingly minor responses to noise pollution to the most serious outcomes. Each honk of a horn, scream of a siren or screech from a train track is met with a corresponding spike in stress hormones, heart rate and blood pressure. Even when individuals become outwardly inured to the ongoing sounds of traffic or aircraft, their bodies are mounting a stress response. Over time, the thinking goes, the cumulative effect takes a toll on the body at the cellular level.

When it comes to your son, he faces the effects of noise pollution at his workplace and, if he lives in the city, at home. While he's at work, he should use a hearing protection device like ear plugs, or ear muffs with soft cushions that fit around the ear and hard outer cups to help block out sound. If his construction company doesn't supply either of these, he should invest in high-quality gear of his own. This will safeguard his hearing as well as offer a measure of protection against the constant barrage of noise.

At home, using a white noise machine at night can help filter out some of the sounds that would otherwise produce a startle reflex. Noise-canceling headphones -- the technology has become advanced enough that you can create a virtual cone of silence -- can also offer protection.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: What causes Crohn's disease? My grandson has had two surgeries for it. Did the food he ate while growing up cause it? I have heard that it is genetic, but we don't know of anyone in his family who has had it.

Dear Reader: It's understandable to want answers about Crohn's disease. A type of inflammatory bowel disease, Crohn's ultimately affects multiple portions of the body, but specifically the large and small intestine, causing diarrhea, abdominal pain, cramping, fatigue, reduced appetite and weight loss. About one in every 500 people within the United States has the disease, and it's most often diagnosed among teenagers and young adults.

And yes, there is a genetic component. About 20 percent of people with Crohn's have a family member with an inflammatory bowel disease, and having a sibling with Crohn's disease increases the risk of getting the disease thirtyfold. For identical twins, the link is even stronger. They have a 50 percent risk of developing the disease if one of the twins has it.

A family history of Crohn's disease isn't the only risk factor. Current and former smokers appear to be at increased risk, as are people who have taken antibiotics or who have had a gastrointestinal infection. Factors that can slightly boost the risk are not having been breast-fed, obesity, chronic use of nonsteroidal anti-inflammatory drugs and the use of oral contraceptives.

That brings us to your question about diet. The rate of Crohn's disease is increasing in the United States and Europe, especially among children. A low-fiber diet appears to be a significant factor. The Nurses' Health Study showed that people who had a higher fiber intake from fruits and vegetables had a 40 percent reduced risk of the disease. Conversely, consumption of saturated fats, processed meats and polyunsaturated fats has been associated with increased incidence of the disease, as have diets high in refined sugar, such as from desserts, candies and sodas.

Many doctors believe that Western diets increase permeability of the intestine, making the intestine more vulnerable to injury. Also, our diets may change our intestinal bacteria in a way that promotes inflammation, leading in turn to Crohn's disease.

To manage Crohn's disease, eliminating foods that have caused past flares will reduce the chance of another flare, as will increasing the amount of dietary fiber and exercise. Because lack of sleep, stress, anxiety and depression can exacerbate the disease, maintaining good mental and emotional health is vital.

On the plus side, therapies have improved. Newer treatments with injectable biologic agents have shown greater efficacy than traditional drugs against Crohn's disease in those with severe cases, even reversing the disease in many patients so that they don't need surgery to remove damaged portions of the bowel.

In short, a myriad of factors could have led to your grandson's disease. What's important now is to ensure that he maintains a proper diet; gets enough sleep and exercise; and limits his stressors.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)