11 thyroid myths and facts: The truth behind thyroid disease

Your thyroid is a butterfly-shaped gland in the front of your neck that helps control how well your body turns the food you eat into energy. A thyroid that doesn’t produce the right amount of hormones can affect everything from your heart rate, metabolism and breathing to your body temperature, digestion and fertility. You can have an underactive thyroid (called hypothyroidism) or an overactive thyroid (hyperthyroidism). There are many conditions that can cause an underactive thyroid or an overactive thyroid.

Thyroid problems are common — nearly 20 million people in the U.S. have some form of thyroid disease.

Myths about the thyroid are common, too. Bhanu Iyer, MD, an endocrinologist and clinical lead of Atlantic Health’s Thyroid Center, helps set the record straight.

Myth: Everyone should be screened for thyroid disease.

Fact: If you don’t have symptoms of thyroid disease and you aren’t pregnant or trying to get pregnant, you don’t need to have routine thyroid screening.

“Targeted testing is recommended only for high-risk groups,” Dr. Iyer says.

This includes patients who are taking medication that can affect their thyroid function (such as lithium or amiodarone) or patients who:

• Are pregnant or are trying to get pregnant
• Have a first-degree relative with thyroid disease
• Have an autoimmune disease
• Have had prior head or neck radiation
• Have Type 1 diabetes

Myth: If you’re tired or gaining weight, you likely have thyroid disease.

Fact: “The classic symptoms of hypothyroidism — fatigue, weight gain, cold intolerance, constipation — are nonspecific and nondiagnostic,” Dr. Iyer says. If your doctor suspects you have an issue with your thyroid, they will order a TSH (thyroid-stimulating hormone) test to measure the amount of TSH you have in your blood.

Myth: If your TSH level is high, you need treatment.

Fact: If you are diagnosed with subclinical hypothyroidism — elevated TSH levels and normal levels of the hormone free thyroxine (T4) — you don’t necessarily need treatment, unless you’re pregnant or trying to conceive.

“Up to 46% of those with TSH levels less than 7 mIU/L will normalize within two years,” Dr. Iyer says.

Typically, treatment begins when your TSH levels are greater than 10 mIU/L on two occasions three months apart, or if you’re younger than 65, if you’re pregnant or trying to conceive, or if you have symptoms. Studies have shown that if you’re older than 65, there is no benefit from treatment and risks include heart problems and osteoporosis (weak and brittle bones).

Myth: If your TSH is normal, ask for additional blood tests.

Fact: “When TSH is within the reference range, additional tests such as free T3, total T4 or thyroid antibodies rarely add clinical value,” Dr. Iyer says.

Additional blood tests can be helpful if your doctor suspects you may have pituitary disease, which can cause your TSH blood test to be unreliable.

Myth: It’s OK to take biotin (vitamin B7) before thyroid testing.

Fact: If you take biotin to support your hair and nail growth, you must stop two to seven days before thyroid testing. Biotin can significantly affect your thyroid tests and may wrongly suggest you have Graves’ disease, low TSH, or elevated free T4 or T3.

Myth: A gluten-free diet will cure Hashimoto’s thyroiditis.

Fact: “Current evidence is insufficient to recommend a gluten-free diet for all patients with Hashimoto’s thyroiditis,” Dr. Iyer says.

If you have Hashimoto’s and celiac disease or a gluten-related condition, a gluten-free diet may reduce your level of thyroid antibodies in your blood and your risk of developing other autoimmune diseases. If you’re diagnosed with Hashimoto’s disease, screening for celiac disease is recommended.

Myth: Broccoli, kale, cabbage and cauliflower can harm your thyroid.

Fact: “There is little proven benefit to avoiding cruciferous vegetables in patients with thyroid disorders,” Dr. Iyer says.

Cruciferous vegetables contain goitrogens, a substance found in food that can interfere with how your thyroid functions. But this is only true for people who already have low levels of iodine and eat a near-impossible amount of cruciferous vegetables (for example, two to three pounds of raw Bok choy a day). Keep eating your broccoli — your body will appreciate those nutrients.

Myth: Soy foods are dangerous for thyroid health.

Fact: Soy doesn’t impact hormones that can affect your thyroid health. You may have also heard that adults who take levothyroxine (a medication used to treat hypothyroidism) shouldn’t eat soy. But that’s not true.

“However, soy formula in infants who were born with hypothyroidism is a notable exception,” Dr. Iyer says.

Soy formula can interfere with how well an infant’s body absorbs their medication to treat hypothyroidism.

Myth: Selenium supplements can treat or cure hypothyroidism.

Fact: Taking selenium supplements won’t treat or cure hypothyroidism. There is some evidence that selenium can help people who have a mild case of Graves’ orbitopathy (a thyroid eye disease). But even then, you have to be careful about how much selenium you take to avoid causing damage to your body.

Myth: Everyone should take iodine supplements to improve thyroid function.

Fact: Most people in the U.S. don’t need extra iodine.

“Iodine supplementation does not beneficially improve thyroid function and may cause harm,” Dr. Iyer says.

The doses of iodine found in kelp and so-called “thyroid support” supplements far exceed the recommended daily intake, which can cause other issues.

Myth: Thyroid nodules likely mean you have cancer.

Fact: “The vast majority of thyroid nodules are benign (non-cancerous),” Dr. Iyer says. “Thyroid nodules are found in up to 68% of adults on high-resolution ultrasound, but only approximately 5 to 15% prove to be malignant.”