To understand thyroid lab values, it is important to understand thyroid physiology. Thyroid stimulating hormone (TSH) is released from the pituitary gland, when there is not enough thyroid hormone in the body. TSH signals the thyroid gland to produce the thyroid hormone T4, inactive thyroid hormone, which is converted to active thyroid hormone, or T3. T3 binds to and activates thyroid receptors throughout the body.
In general practice, TSH is assessed first when evaluating thyroid function. If TSH is abnormal, then T4 is tested. In hypothyroidism, TSH is elevated and T4 and T3 are typically low. When assessing thyroid function from a more holistic approach, all three values are tested to determine if an individual may not be in an overt hyperthyroid state, but may still need thyroid support or support to convert to active thyroid hormone, therefore having an opportunity to decrease disease progression.
In Hashimoto’s thyroiditis a patient has elevated anti-thyroglobulin (anti-TG) and/or anti-peroxidase (anti-TPO) antibodies. Conventionally, antibodies are not routinely tested. From a holistic medicine perspective, it is important to identify autoimmune thyroiditis to best direct individualized treatment. Hashimoto’s patients may also show elevated antibodies before other lab values become abnormal. In this case, assessing the whole picture provides an opportunity for preventing disease progression.
There is also discrepancy regarding the normal upper limit for TSH, which is currently 4-5 mU/L. Some evidence suggests that an upper limit of 2.5 mU/L may be a more accurate measurement of healthy thyroid function. Supporting thyroid health may be helpful in patients with symptoms of hypothyroidism, with TSH values on the high end of “normal”. Testing thyroid antibodies in this demographic may also be beneficial, to determine if auto-immunity may be a cause of symptoms.
In summary, a holistic medical provider will likely evaluate TSH, free T4, free T3, and thyroid antibodies when assessing thyroid health in order to tailor a treatment plan specific to individual health needs.