What are the shortcomings of our current thyroid tests?

Dr. Jack Merendino, MD
Endocrinology Diabetes & Metabolism
This is a big topic and an area of major disagreement among endocrinologists, so thoughtful and experienced endocrinologists might give different answers. I would start by saying that there is no shortcoming in our current thyroid tests themselves, only shortcomings in the interpretation of those tests. In other words, the tests themselves -- blood tests, thyroid ultrasounds and nuclear medicine tests -- are quite good, but they are often misinterpreted.

The biggest problem often results when doctor sees a test result and automatically believes that he or she knows how a patient must be feeling. However, it is common for a person who does not feel well to have “normal” test results, and person who feels just fine to have an “abnormal” result. In addition, thyroid hormone levels fluctuate over time in the same person, so interpreting one set of tests may be misleading.

Let’s take a very common example: The thyroid stimulating hormone (TSH) level is the most commonly used test to screen for thyroid problems. A high level is usually associated with an underactive thyroid (hypothyroidism) while a low level usually means that the thyroid is overactive (hyperthyroidism). However, the normal range for this test is always established for a population and never for an individual. One person may have a TSH level that is in the high-normal range but feel poorly and respond well to treatment with thyroid medication, while another person may have a value that is higher than the normal range and feel quite well. Unless the value is very high there is probably no reason to treat this person. One could argue that this “abnormal” value may be “normal” for him or her.

As a final issue, some people believe that their symptoms are the result of a thyroid problem when they are really suffering from a different medical problem, including the effects of overweight and a lousy diet, poor sleep, inadequate exercise or anxiety and depression related to issues at work or home. Before concluding that someone has a thyroid problem, it is important to exclude these other very common issues because the symptoms may be very similar.
Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)

Your hypothalamus is responsible for making the hormone that causes your pituitary to produce thyroid-stimulating hormone - a marker for thyroid disease. The problem is that most docs treating the symptoms of thyroid problems (like weight gain and fatigue) treat based on a number that really doesn't make perfect sense. We docs should be looking at both forms of thyroid hormone (free T4 and T3 levels) as well as TSH levels.
Your TSH levels are from your pituitary; they're your internal dimmer trying to make the lights bright enough to read. So your TSH levels go up when your thyroid isn't pumping out enough T4 and T3, in an effort to increase your thyroid gland's production of T3 and T4. But sometimes your pituitary fails to succeed or the wires in your thyroid are frayed so you cannot produce all the T3 and T4 you need. So we docs try to help by giving you more - but many times we are guided by trying to return your levels to normal rather than addressing your symptoms. To boot, we often treat it with a drug that doesn't always help. But this issue is tough: There's a complex and delayed reaction to these drugs. (It takes four to eight weeks to get stable levels of these drugs after you make a change in doses.)
Many times, you need to help your doc know how you feel and maybe push to get treated with a bioidentical thyroid hormone that doesn't just adjust the numbers in your blood test, but helps the way you actually feel.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.