The thyroid is an important hormonal gland that regulates metabolism and growth. Because thyroid hormones control metabolism in all the cells of your body, a deficiency affects virtually all bodily functions.
Symptoms of low thyroid hormone include:
Fatigue
Increased cholesterol levels
Low libido
Low body temperature (feeling cold) or cold hands and feet
Carbohydrate cravings
Tendency towards constipation
Irregular menstrual periods
High cholesterol
Thinning hair
Dry skin or brittle nails
Pain or stiffness of joints
Muscle aches
Water retention
Depression
Headaches
Poor concentration and memory
Low thyroid function can be due to a dysfunction at different parts of the hormone production pathway. In general healthcare, it is common to assess thyroid function based off of only TSH. Below are 3 common conditions that may be present even if TSH is reported "normal".
Low T3 T3 is the most active and useable form of thyroid hormone that is used by our cells. Free T3 is the unbound portion of T3 that can actually enter our cells. Many individuals with hypothyroid symptoms don’t properly convert T4 to T3. This conversion can be inhibited by inflammation and requires selenium (Brazil nuts are a great source) and zinc.
Reverse T3 As discussed above, T4 must be converted into T3 before the body can use it. Some of T4 is converted into an inactive form of T3, Reverse T3 (RT3). RT3 binds and blocks the hormone receptor sites instead of activating them. During times of extreme stress, including extreme dieting, chronic stress and illness, cortisol will trigger the body to convert more T4 into Reverse T3. In this case, your TSH, T4 and even T3 scores may fall within "normal ranges" while still experiencing thyroid symptoms.
The best way to lower RT3 levels is by reducing total body inflammation, identifying and treating any chronic illness or infection, improving digestive function, and managing stress levels.
Hashimoto’s Disease The majority of hypothyroid cases are due to Hashimoto's disease, an auto-immune disease where the body confuses it's own thyroid gland as foreign and attacks and destroys thyroid tissue. People with Hashimoto's may experience both hypothyroid and hyperthyroid symptoms. As cells are destroyed, hormone stores are released into the bloodstream (hyperthyroid) and lead to depletion of thyroid stores (hypothyroid). Testing for thyroid antibodies is key here, as the treatment strategy is completely different than in previous cases, and treating Hashimoto's as general hypothyroidism may actually make the patient worse.
It is also important to rule out heavy metal toxicity as the cause of Hashimoto's. Treatment options for Hashimoto's disease include adhering to an anti-inflammatory, grain-free diet to help lower antibodies, as well as herbal and nutritional supplementation.
Recommended Labs for Proper Thyroid Assessment:
TSH
Free T4
Free T3
Reverse T3
Thyroid Peroxidase Antibodies
Thyroglobulin Antibodies
Thyroid hormone conversion problems can be caused by a number of common issues including significant stress, heavy metal toxicity, depression, improper or extreme dieting, insulin resistance, diabetes, autoimmune diseases, chronic inflammation, obesity, inadequate absorption of nutrients, infections, iron deficiency, and many more. Any one of these issues could cause a patient to experience hypothyroid symptoms and requires proper testing and treatment.