Dear Dr. Gott: A friend of mine recently underwent chelation. It has something to do with filtering the blood in your system.

I'm not sure whether this is a medical hoax or valid treatment. I cannot find anything in medical journals indicating whether or not the AMA has approved this. What is your opinion?

Dear reader: It depends on why he is having treatment and involves the administration of a synthetic amino acid known as ethylenediamine tetraacetic acid (EDTA) into the veins.

It is a recognised treatment for heavy-metal poisoning, particularly lead and mercury. The therapy works by binding the metals and creating a compound that is ultimately excreted in the urine.

In addition, EDTA binds calcium, one of the components of atherosclerotic plaque. This led to speculation almost 50 years ago that EDTA could remove calcium deposits from build-ups present in the arteries.

Thus, chelation therapy was proposed both to treat atherosclerosis and prevent it from forming.

The American College of Cardiology, the American Heart Association and organised medicine as a whole oppose chelation for this purpose, citing insufficient evidence to justify it as valid treatment; therefore, if your friend has had heavy-metal exposure, I can endorse the therapy.

Otherwise, I don't. And I would be surprised if his physician or cardiologist would consider it, either.

While some people will show what appears to be significant improvement following therapy, chelation is not without risk. There is a danger of kidney failure, cardiac arrhythmias, bone-marrow depression, allergic reactions and more.

There are reported cases of people on dialysis as a result of kidney failure caused, at least in part, by the therapy.

Speak with your friend. If he or she is undergoing therapy for the right reasons, so be it. If not, perhaps he or she will choose to listen to your concerns and seek a second opinion.

Dear Dr. Gott: I am a 61-year-old male in good health except for chronic sinus infections. I've been told my CT scan revealed all of my sinuses are infected, and my hearing has been reduced due to the regular presence of fluid in my ears.

I've been through several courses of antibiotics, nasal sprays, steroids and now prednisone — with little to no relief.

I've seen two ENT specialists. The first recommended balloon sinuplasty, and the second endoscopic sinus surgery.

Both claim their procedures are minimally invasive and effective. As the recommendations are so different, I am unsure what to do.

Can you please give your opinion regarding each procedure so I might make an informed decision?

Dear reader: Balloon sinuplasty is performed on people suffering from sinusitis. It is not recommended for large nasal polyps or when appreciable scarring from prior nasal surgery is present.

A small, balloon-type catheter is inserted to open the sinuses and blocked passages to allow restoration of normal sinus drainage.

The technique appears safe and effective, and recovery is rapid.

This is a reasonably new procedure, and physicians are still determining when it is the best treatment of choice.

Endoscopy involves inserting a tube with a camera attached into the nose to allow a physician a view of the sinuses. Surgical instruments are simultaneously inserted alongside the endoscope.

The instruments allow the removal of material such as polyps or bone that may be blocking sinus openings.

Endoscopy is performed when medication has failed to cure chronic sinusitis and is the preferred surgical method for most cases of chronic sinusitis.

The procedure can be performed in a physician's office, clinic or hospital setting under anaesthesia.

Minor bleeding and discomfort may occur for up to two weeks following the procedure.

Dr. Peter Gott is a retired physician and the author of the book "Dr. Gott's No Flour, No Sugar Diet," available at most chain and independent bookstores, and the recently published "Dr. Gott's No Flour, No Sugar Cookbook." Write directly to Dr. Gott c/o United Media, 200 Madison Ave., 4th fl., New York, NY 10016.