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Top Reasons to Test Your Thyroid

Article at-a-glance:

  • The thyroid gland is sometimes called the “master gland.”
  • When the thyroid isn’t working well, it can create symptoms throughout the body. 
  • Since symptoms can be wildly different in different people, ranging from headaches and brain fog to gastrointestinal disturbances, menstrual irregularities and dry skin, when the thyroid gland is the underlying cause, it can go unrecognized.

by Dr. John Neustadt

Hormones from the thyroid gland regulate metabolism in every cell; therefore, a deficiency of thyroid hormones can affect virtually all body functions. For that reason, the thyroid gland is sometimes called the “master gland.” When the thyroid isn’t working well, it can create symptoms throughout the body. 

Because these symptoms can be wildly different in different people, ranging from headaches and brain fog to gastrointestinal disturbances, menstrual irregularities and dry skin, when the thyroid gland is the underlying cause, it can go unrecognized. Understanding a bit about the thyroid gland and symptoms that poor thyroid control causes will help you know when you should think about getting your thyroid checked and what you can do about it. 

A Butterfly-Shaped Gland

The thyroid gland is a butterfly-shaped gland that sits at the base of the neck. It produces the thyroid hormones levothyroxine (T4) and triiodo-thyronine (T3). About 80% of thyroid hormone is T4 and about 20% is T3. T4 is inactive and is converted into active T3 in different tissues throughout the body.  

Thyroid Stimulating Hormone (TSH) is a hormone released from the anterior pituitary in the brain. It stimulates the thyroid gland in the neck to produce T4 and T3. Often TSH is used as a basic, although incomplete, screen of thyroid function. A more complete screen of thyroid health tests TSH, T4 and T3. TSH is also used to monitor people taking thyroid hormone replacement. 


Symptoms of hypothyroidism vary with age. In older adults, decreased cognitive function may be the only manifestation. According to the American Academy of Family Physicians, about one in every 300 adults has low thyroid function, called hypothyroidism.1 As we age, however, hypothyroidism becomes more common. It’s estimated that up to 20% of women over 60 years old have hypothyroidism.2 

Since thyroid hormones affect every system in the body, it’s not surprising that the list of symptoms caused by low thyroid is long and includes:1,3 

  • Brain fog
  • Brittle hair
  • Cold intolerance
  • Constipation
  • Decreased motivation
  • Depression
  • Difficulty losing weight
  • Difficulty processing information
  • Diffuse muscle pain
  • Dry skin
  • Fatigue
  • Gastrointestinal distress
  • Hair thinning or loss
  • Heart palpitations
  • Increased cholesterol, a risk factor for heart disease and stroke 
  • Infertility
  • Lightheadedness
  • Menstrual irregularities
  • Muscle weakness
  • Poor circulation
  • Poor exercise tolerance
  • Poor memory
  • Visual disturbances
  • Weight gain
  • And more


While less common than hypothyroidism, an overactive thyroid is called hyperthyroidism and also causes many symptoms. These include rapid heartbeat, insomnia, excessive sweating, loss of muscle mass, osteoporosis, anxiety and more. 

Autoimmune Thyroid Disorders

An autoimmune condition, where the body’s own immune system attacks the thyroid gland can cause both hypothyroidism and hyperthyroidism. 

When low thyroid function is caused by an autoimmune condition, it’s called Hashimoto Thyroiditis. Dr. Hashimoto was the researchers who discovered this condition, and like all explorers who discover something new, he got naming rights. This can result in periods where the body is creating normal amounts of thyroid hormone, followed be not enough thyroid hormone. Eventually, as more and more of the thyroid gland becomes affected, chronic hypothyroidism sets in. 

An autoimmune thyroid condition can also create excessively high thyroid hormone. This form of hyperthyroidism is called Graves’ Disease. This is characterized frequently by excessive sweating, heart palpitations, rapid heartbeat, anxiety and insomnia.  

People who have other autoimmune diseases have a higher risk for autoimmune thyroid diseases. These have repeatedly by associated with Celiac Disease. A highly significant association exists between Celiac Disease and autoimmune thyroiditis (Graves’ disease and Hashimoto’s thyroiditis).4,5,6  

Vitamin D deficiency has also been associated with Hashimoto Thyroiditis. In patients with low vitamin D and Hashimoto Thyroiditis, supplementing with vitamin D has improved the condition.7,8 

If Hashimoto Thyroiditis is suspected, in addition to testing for TSH and possibly T4 and T3, two additional tests are typically ordered. They are the anti-thyroglobulin antibody (anti-TG antibody) and anti-thyroid peroxidase antibody (anti-TPO antibody) tests.

If Graves’ Disease needs to be ruled out, doctors will typically order a radioactive iodine uptake test. Your body needs iodine to make thyroid hormone. If a high amount of radioactive iodine is taken up by the thyroid gland it helps determine if Graves’ disease is the cause of the hyperthyroidism. 

Decreased Conversion of T4 to T3

Another situation can exist in which your body can be producing enough TSH an T4 but is having difficulty converting the T4 into the active T3 hormone. Two syndromes in which this has been identified are called “Euthyroid sick syndrome (ESS),” “low T3 syndrome” and “Non-Thyroidal Illness Syndrome (NTIS)” These are frequently used interchangeably to describe problems arising not from the thyroid gland itself, but rather from the inability for tissues throughout the body to convert T4 to T3. 

Since T3 is the active hormone, even then TSH and T4 are normal, low T3 can cause the same symptoms as seen in overt hypothyroidism. In these syndromes, T4 levels are generally normal, but can also be slightly elevated and TSH is either normal or slightly low. If you only test TSH, which again is the standard screening test in conventional medicine, and don’t also test T4 and T3, the TSH can come back normal, you may miss that the T3 is low and therefore lead to the incorrect conclusion that you don’t have a thyroid problem.  

A 2017 article published in the journal Frontiers in Immunology reported on a series of cases of non-thyroidal illness syndrome caused by mold exposure.9 Nine women, ages 31–49 years old who had a history of mold exposure and a variety of symptoms compatible with NTIS were treated with levothyroxine. Levothyroxine is bioidentical T4 and is the standard of care in conventional thyroid hormone replacement therapy. They did not improve on the levothyroxine. In contrast, when the volunteers were prescribed T3 replacement therapy, all nine of them improved.

Should You Test Your Thyroid? 

If you struggle with symptoms that could indicate a thyroid problem, you may want to get tested. While many different things can cause these symptoms, the thyroid test is a common screen that is recommended as a routine test by some medical organizations.

The American Thyroid Association recommends all men and women aged 35 years and older should be screened every five years. The American Association of Clinical Endocrinologists recommends that older folks should be screened, especially women. The American Academy of Family Physicians recommends that people over 60 years old should be tested. And the American College of Physicians recommends that women over 50 who have symptoms that could indicate a thyroid problem should be screened.10

The bottom line is that if you believe your thyroid may be involved in what you’re experiencing, testing can provide valuable information to help you make important health decisions. 

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1Gaitonde DY, Rowley KD, Sweeney LB. Hypothyroidism: an update. Am Fam Physician. 2012;86(3):244-251.

2Canaris GJ, Manowitz NR, Mayor G, Ridgway EC. The Colorado thyroid disease prevalence study. Arch Intern Med.2000;160(4):526-534.

3Gaby AR. Sub-laboratory hypothyroidism and the empirical use of Armour thyroid. Altern Med Rev.2004;9(2):157-179.

4Kaspers S, Kordonouri O, Schober E, et al. Anthropometry, metabolic control, and thyroid autoimmunity in type 1 diabetes with celiac disease: A multicenter survey. J Pediatr. 2004;145(6):790-795.

5Liontiris MI, Mazokopakis EE. A concise review of Hashimoto thyroiditis (HT) and the importance of iodine, selenium, vitamin D and gluten on the autoimmunity and dietary management of HT patients. Points that need more investigation. Hell J Nucl Med. 2017;20(1):51-56.

6Freeman HJ. Endocrine manifestations in celiac disease. World J Gastroenterol. 2016;22(38):8472-8479.

7Mazokopakis EE, Papadomanolaki MG, Tsekouras KC, Evangelopoulos AD, Kotsiris DA, Tzortzinis AA. Is vitamin D related to pathogenesis and treatment of Hashimoto’s thyroiditis? Hell J Nucl Med. 2015;18(3):222-227.

8Chaudhary S, Dutta D, Kumar M, et al. Vitamin D supplementation reduces thyroid peroxidase antibody levels in patients with autoimmune thyroid disease: An open-labeled randomized controlled trial. Indian J Endocrinol Metab. 2016;20(3):391-398.

9Somppi TL. Non-Thyroidal Illness Syndrome in Patients Exposed to Indoor Air Dampness Microbiota Treated Successfully with Triiodothyronine. Front Immunol. 2017;8:919.

10Garber JR, Cobin RH, Gharib H, et al. Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Thyroid. 2012;22(12):1200-1235.

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