Post: Who should be tested? Should it be part of a routine annual physical?
Dr. Garber: Thyroid testing was not part of President Bush Sr.’s annual physical. If you remember, his hyperthyroidism was diagnosed after he had problems breathing while jogging. Today, the American Thyroid Association recommends screening every five years, starting at age 35. Universal screening is not felt to be cost effective, but most experts would recommend testing women over 60, those with symptoms, and then targeted subgroups such as smokers or those with a personal or family history that includes autoimmune conditions.

Having symptoms of thyroid disease does not mean one has it. Making a diagnosis solely based on symptoms can be inordinately difficult. However, the diagnosis becomes straightforward by testing for it. People should target themselves based on symptoms. If you are aware of thyroid conditions and believe you are experiencing enough symptoms, it is easy for a doctor to justify testing.

In addition, doctors should target patients on the basis of other risk factors. For example, I would check someone who comes to my office saying “I feel perfectly well” if I felt a lump in their thyroid or there was a compelling history. Thyroid disease is very easy to overlook.

Post: Hypothyroidism seems to be frequently in the headlines. Any reason why?
Dr. Garber: I think we live in an era in which people are seeking holistic approaches—sometimes in a good sense, and sometimes in a way that they can get exploited, in my view. Thyroid disease lends itself to an approach by some practitioners that is generally symptom-based. The idea that a constellation of symptoms dictates a diagnosis, despite the lack of conventional proof, is where the tension comes in.

“What Your Doctor Won’t Tell You” is a great headline. What people don’t read about is the downside of taking thyroid hormone products. It is not a free ride. My major concern is the risk of over-treatment. The second concern is that by treating symptoms without a certain diagnosis, a doctor will overlook another important fact or condition. Hypothyroidism can masquerade as depression, but depression can masquerade as hypothyroidism, for example.

Then there is the cost of medicine and the cost of testing. I would never argue with someone who says they feel a certain way, but the data doesn’t support that treating marginal disease necessarily leads to benefit. If a person has borderline thyroid stimulating hormone (TSH) levels and no symptoms or compelling medical reason, such as planning a pregnancy, treatment may not be called for. If people are borderline and symptomatic, of course, try to treat it. But give it a limited time. Don’t just commit people to medicine and put them at risk for being over-medicated or being subject to costs and missing other possible reasons for what they are feeling. Fatigue is the 21st century complaint. We’ve got a lot of reasons to be tired besides our thyroid.

Thyroid drug analogs, or copies of thyroid hormone, are also being mentioned in the press. As recently as March 11, 2010, the New England Journal of Medicine featured a follow-up article on the subject. The concept is to design a thyroid hormone analog that has the benefits of, say, inducing weight loss or lowering cholesterol, but not the drawback of stimulating the heart.

Post: How far away is this concept from actual reality?
Dr. Garber: It was pretty far away until March 11. These researchers demonstrated that one particular analog did not affect the heart, and did lower cholesterol.

Another drug analog was studied in heart disease patients. Many lost weight, but 60 percent to 70 percent of the patients dropped out of the study because they felt lousy. Since the study was not designed to analyze weight loss, researchers couldn’t do a good job of finding out whether people ate less because they had a lousy appetite, which is a terrible way to lose weight, as opposed to eating less because their appetite isn’t as high.

Post: Is there a better test for thyroid hormone levels on the horizon?
Dr. Garber: Not at present. The current discussion is whether we need to take a new look at what is considered the normal range for TSH levels, depending on the situation. Data show that some TSH levels we now consider elevated—in the elderly—may not represent hypothyroidism. And, on the other hand, new guidelines are definitely going to set a lower TSH of approximately 2.5 as the upper normal in the first trimester of pregnancy.

Post: What is the link between thyroid hormone and heart attack and heart disease?
Dr. Garber: If you are profoundly hypothyroid, you often become hypertensive and hypercholesterolemic. As a result, your vessels become constricted as well. Hyperthyroidism affects the heart mostly through rhythm disturbances characterized by fast heart rates including atrial fibrillation and sinus tachycardia.

Post: Are there other new developments you would like to mention?
Dr. Garber: A recent discovery suggests there is a subgroup of people with a certain genotype that are more likely to feel better on a T3-T4 combination therapy. We are not at the point that we are going to start doing genetic testing on people, but the study found that certain people with a certain genotype were more likely to feel better on combination therapy. From a hot, new, and conceptual point of view, the discovery may provide yet another role for genetic testing.