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If you’ve long struggled with your weight – or just recently put on some unexplained poundage – you’ve probably wondered about the health of your thyroid.
After all, while more than 12 percent of Americans develop a thyroid condition in their lifetime, up to 60 percent of those sufferers are undiagnosed, according to the American Thyroid Association. And since the thyroid gland is in charge of producing T3 (triiodothyronine) and T4 (thyroxine), two hormones that, among other things, are in charge of setting your basal metabolic rate – the number of calories you burn every day just to stay alive – thyroid issues can easily trigger significant weight loss or, more commonly, weight gain, explains Dr. Peter A. Kopp, an endocrinologist at Northwestern Memorial Hospital in Chicago.
So how do you know if your thyroid is to blame for your weight problems? It’s important to work with a specialized physician to take an honest and thorough look at your symptoms, health history and biological markers for hormonal disturbances, Kopp says. After all, while most everyone would like a magic pill, even if it is a synthetic thyroid hormone pill, to magically lose the pounds, a thyroid disorder is a serious, life-altering diagnosis – not something to wish for.
How Your Thyroid Works
To understand all of the testing that goes into a diagnosing hyperthyroidism, an excess of thyroid hormones, or hypothyroidism, a lack of thyroid hormones, it’s helpful to fist understand the delicate biological and chemical interplay that determines your thyroid levels.
The process starts in the brain’s hypothalamus, with it producing thyrotropin-releasing hormone, or TRH, which triggers the pituitary gland, located at the base of the brain, to produce thyroid-stimulating hormone (called TSH for short). TSH then travels through the bloodstream to the thyroid gland, a small, butterfly-shaped gland situated in the front of the neck, causing the thyroid gland to release T3 and T4, explains Dr. Naresh C. Rao, clinical assistant professor of family medicine at the NY College of Osteopathic Medicine.
Within the body, enzymes convert some of the T4 into T3, the more biologically active form of the hormone. Meanwhile, the amount of TRH and TSH produced is largely controlled by the amount of T3 and T4 in the body, Kopp says.
It’s a complicated process, and issues can arise at every step along the way, he says. For instance, while thyroid disease can reduce production of T3 and T4, independent of TSH levels, pituitary issues can keep TSH from ever getting high enough to trigger thyroid hormone function. And dysfunction in the brain’s hypothalamus can put the breaks on the whole process before it even starts.
Know the Symptoms and Risk Factors
Symptoms of thyroid conditions exist on a sort of two-sided coin. On one side, there’s hyperthyroidism (too much thyroid hormone), which causes the body’s cells to go into a sort of metabolic overdrive. Weight loss, anxiety, irritability, sweating, difficulty sleeping, as well as rapid, irregular and pounding heartbeats are all common symptoms, and any combination of them (and others) can exist in people with hyperthyroidism. The most common form is called Grave’s disease, which often causes swelling at the base of the neck, a sign of an enlarged thyroid gland.
On the other side, you had hypothyroidism (too little thyroid hormone), which causes the same cells’ metabolic processes to slow to a crawl. Results include weight gain, depression, poor memory, increased sensitivity to cold, fatigue, muscle weakness and slowed heart rates. The most common cause of hypothyroidism is Hashimoto’s disease, an autoimmune condition in which the immune system destroys cells within the thyroid, preventing the production of thyroid hormones.
What You Need to Know About Testing
Currently, controversy swirls around what should and shouldn’t be tested in order to identify thyroid imbalances. For instance, while traditionally, a simple TSH blood test has been used to identify thyroid issues, TSH doesn’t necessarily indicate that the thyroid is producing the needed hormones. It only means the pituitary is instructing it to do so, Kopp says.
For that reason, depending on a patient’s symptoms, physical examination and family history, some physicians will perform other tests.
The most commonly performed test, apart from TSH, is a blood test for free T4. That’s because free T4 – which is not attached to binding proteins and floats freely through your bloodstream – is the only form of T4 that is able to enter cells and exert its effects, Rao says. (While total T4 can also be evaluated, it tends to be less helpful in evaluating thyroid function.) However, the current free T4 testing is less than perfect and should be used in tandem with TSH.
What’s more, as the thyroid gland also produces T3, and some T4 converts to T3 within the body, it can be helpful to evaluate T3 levels in the blood, says Kopp, noting that in some individuals, hypothyroidism can be due to a decreased conversion rate of T4 to T3. So, in these patients, without T3 testing, hypothyroidism could be easily missed. However, T3 testing is most often used to diagnose hyperthyroidism or to determine the severity of a patient’s hyperthyroidism. And, unfortunately, T3 testing isn’t always accurate.
Apart from these, other ways to gain a more complete picture of thyroid function and health include thyroid antibody tests, radioactive iodine uptake, or RAIU, and ultrasound imaging.
For instance, since hypothyroidism is commonly caused by an autoimmune condition, thyroid antibody tests can also be performed to determine if the immune system is working to damage the thyroid gland, Kopp says. In rare cases, however, the immune system can also stimulate the thyroid to produce excess hormones.
And since the thyroid gland uses iodine to create both T3 and T4, RAIU, which tracks how much iodine is taken up by the thyroid gland, can also be used to help gain a better picture of thyroid function. For testing, the patient swallows an iodine pill and then multiple scans are performed of the thyroid gland, typically around four to six hours, and again around 24 hours, following ingestion.
Lastly, if the thyroid gland is found to be enlarged during a physical exam, which involves the physician palpating the neck, imaging tests, such as a thyroid ultrasound, can add valuable insight about any physiological abnormalities or malignancies within the gland, Rao says.
It’s a complicated process and, unfortunately, at this point, proper testing can feel as much like an art as a science. So while primary care physicians can and do regularly screen for thyroid issues, Kopp recommends seeking out a dedicated thyroid specialist. By working with someone who is well-trained in evaluating thyroid function and is up to date on current research and advances, you can help eliminate repeat testing and ensure that you get the most accurate diagnosis possible. To find a thyroid specialist near you, go to thyroid.com.
Written for USNews.com