Beyond the Thyroid Panel: The Essential Hypothyroid Lab Tests Your Doctor Doesn’t Order
Research estimates that there are up to 300 million people worldwide suffering from thyroid disease, yet more than half are likely unaware of their condition. Hypothyroidism is one of the most under-diagnosed and misdiagnosed health problems that I see in my practice, especially in women between the ages of 30 – 50. Hypothyroid patients are falling through the cracks of mainstream medicine, left to suffer with debilitating fatigue, constipation, weight gain (despite diet and exercise) and an overall poor quality of life.
TSH (thyroid stimulating hormone) has long been considered the gold standard for the diagnosis of low thyroid function. However, a new study from the Journal of Clinical Endocrinology and Metabolism question this methodology due to the fact that normal TSH levels do not necessarily equate with optimal thyroid function. All of my patients with suspected hypothyroid are given a requisition for a full thyroid panel, testing TSH, free thyroid hormone levels (T3 and T4) and antibodies against the thyroid gland. I’ve seen hundreds of women that were dismissed as having ‘normal thyroid function’ after their lab work failed to show elevated TSH levels. Upon further investigation, over 90% of these women with complaints of fatigue, low temperature and weight gain had low free thyroid hormone levels and elevated antibodies against the thyroid gland. It is essential to look at both free T4 (precursor/less active thyroid hormone) and free T3 (the metabolically active form of thyroid hormone) to diagnose and treat thyroid hormone conversion issues. Low conversion is common since it can be effected by hormone levels (low progesterone/high estrogen), nutritional deficiencies (specifically B vitamins and selenium), and chronic stress. TPO and anti-thyroglobulin anti-bodies are also a key part of your thyroid health workup since they tell us whether or not your low thyroid function is due to an autoimmune disease. Conventional medical doctors rarely run these tests since the treatment of thyroid disease is essentially the same regardless of the cause [see my post about the limitations of Synthroid]. While you’re likely convinced of the importance of a full thyroid panel when diagnosing thyroid disease there are a few additional tests that I think are key to developing a truly holistic thyroid treatment plan.
The following lab tests are abnormal in the majority of my thyroid patients and can be a major contributing factor to symptoms like fatigue, hair loss, weight gain and brain fog. While the first step in any thyroid treatment plan should be to run a full thyroid panel, the following tests are also critically important to getting my patients back to feeling their best and to fully address thyroid disease at it’s root cause:
- Iodine testing: Iodine is one of the building blocks that the thyroid uses to produce free thyroid hormones – T3 and T4. In fact, the 3 and 4 in T3/T4 actually refers to the number of iodine molecules bound to that hormone. If you don’t have enough iodine in your body, you cannot make enough thyroid hormone. Since iodine is released from the body through the urine, the best way to determine iodine deficiency is to measure the amounts of iodine excreted in the urine. Iodine is key to optimal thyroid health but both too much and too little can be harmful to the thyroid gland. I frequently use the iodine provocation test with my patients to assess whole body sufficiency and to determine appropriate dosing of iodine. The test consists of ingesting 4 tablets 50 mg iodine then measuring urinary iodide levels in the following 24 hours. This test is based on the concept that the human body has a mechanism to retain ingested iodine until whole body sufficiency for iodine is achieved.
- Ferritin (iron storage protein): Among the many nutritional deficiencies that are effected by low thyroid activity, iron-deficiency is one of the most common. Iron is needed to form ATP which is key to energy production and plays many other essential roles in the body. Common signs of low iron include fatigue, hair loss, feeling cold and shortness of breath. Your thyroid also requires adequate iron levels in order to make and activate thyroid hormone. Hypothyroidism can even worsen anemia since most people with hypothyroidism have slow digestive systems due to a lack of digestive acid. Gastric acid is essential for the uptake of minerals like iron, so it stands to reason that low thyroid activity may further alter iron absorption. It’s especially important to test you iron levels if you experience heavy menstrual periods, have IBS or are a vegan or vegetarian.
- ANA: Antibodies are proteins found in the blood stream that are made as part of your body’s natural immune response. Normally, the immune system produces these antibodies to respond to external pathogens like viruses and bacteria. However, when a person has an autoimmune disease, the immune system malfunctions and starts producing large amounts of antibodies directed against a patient’s own body tissues. These self-directed antibodies are referred to as autoantibodies, and can be measured by a simple blood test, called ANA. Studies show that having a diagnosis of autoimmune hypothyroidism can drastically increase your chance of developing other autoimmune diseases in the future. While not a great stand-alone test, ANA testing can be a useful adjunct screening tool to examine the overall level of autoimmune processes occurring within the body.
- Vitamin D: Low vitamin D levels have been implicated in the development of autoimmune thyroid conditions, especially Hashimoto’s Disease (the most common cause of hypothyroidism). Vitamin D is important to the immune system and chronically low vitamin D levels can increase your chances of developing any type of autoimmune disease. Moreover, symptoms of Vitamin D deficiency can also overlap those of hypothyroidism. They include fatigue, muscle pain and low mood. Studies show that most Canadians are deficient in vitamin D and require some supplementation in the colder months. Vitamin D is a fat soluble vitamin, meaning it can be stored in fat and muscle tissues. This is why it’s important to test your vitamin D levels before you supplement. Vitamin D tests typically aren’t covered under OHIP in Ontario but your Naturopath or Functional medicine doctor can run these labs for you at a minimal cost.
- Food sensitivity testing: Hashimoto’s thyroiditis is an autoimmune disease, and the most common cause of hypothyroidism in North America. Recent studies show that a phenomenon called “molecular mimicry” is likely a contributing factor to this disease. Molecular mimicry refers to an extremely common mechanism by which pathogens modulate the immune pathways of humans. In genetically predisposed patients, molecular mimicry can turn a defensive immune response into autoimmune disease. This means that autoimmune hypothyroidism can occur when bacteria and food particles leak into your blood stream through your gut lining, causing your immune system to attack the thyroid gland. Food sensitivity testing (FST) can tell us which foods are creating an immune response in your blood stream. Food particles are tested against your blood cells and if an antibody complex is formed in the lab this means it’s likely that the same thing is happening inside your body. FST is also usefully for determining the degree to which a ‘leaky gut’ may be contributing to hypothyroid symptoms.
- Vitamin B12: Recent studies suggest that over 50% of patients with an autoimmune thyroid condition also have chronically low B12 levels. This occurs because hypothyroidism can cause decreased stomach acid levels, thereby compromising your ability to absorb this essential vitamin. Adding supplementary B-12 to hypothyroid patients has been shown to improve fatigue, memory and mood symptoms. If your B12 levels are low a series of weekly vitamin B12 injections can be a wonderful treatment to improve energy levels, and reduce brain fog.
- Cholesterol panel: When thyroid hormone levels are low it impact’s your liver’s ability to break down and remove LDL (‘bad’) cholesterol. This is why hypothyroid patients often have hypercholesterolemia, which may also need to be addressed as part of a comprehensive treatment plan. Even patients with subclinical hypothyroidism, or mildly decreased thyroid function, can have higher than normal LDL cholesterol.