Thyroid hormone is the most commonly prescribed hormone. It regulates the body’s metabolism, body temperature, and energy production. The thyroid gland will release less hormone with aging and can be affected by disease (thyoiditis). A hypo-thyroid (low) state would typically cause fatigue, weight gain, water retention, hair thinning, low body temperature, and cold intolerance. Having more than one of the above raises the suspicion for a thyroid deficiency. Laboratory testing will confirm it, however, only if done correctly. Too often a screening test called thyroid stimulating hormone (TSH) is used by itself. While useful, a TSH needs to be combined with the measurement of actual blood levels of the two main thyroid hormones (T4 and T3) to get a complete picture of thyroid health.
The two main mistakes made with thyroid hormone therapy is missing the deficiency itself (improper testing) and using the wrong form of thyroid hormone for treatment. Synthetic T4 (Synthroid, Levoxyl) is the most commonly used drug for thyroid replacement. However, the patient’s response to T4 is often poor. That is due to the relative weak activity of T4 compared to the highly active form of thyroid, T3. The body needs to convert the inactive form of thyroid (T4) to the active form (T3). Aging, among scores of other conditions, decrease the body’s ability to convert T4 to T3.
Therefore, it is more appropriate and therapeutic to combine T4 and T3 when prescribing thyroid hormones. We use both Armour thyroid (a natural T4, T3 combination) or synthetic T4 plus a slow release compounded T3 depending on the individuals laboratory results AND clinical response. Sadly, when thyroid levels are improperly interpreted as normal, the patient usually has an antidepressant (SSRI) prescribed. The drug is used to treat their symptoms believed to be from depression, which can mimic a hypothyroid state.