Causes of an Underactive Thyroid

The thyroid makes two primary hormones. They are:

  • Thyroxin (T4). T4 is the storage form of thyroid hormone. The body uses it to make triiodothyronine (T3), the active form of thyroid hormone. Most synthetic thyroid medications, such as Synthroid and Levothyroxine, are pure T4 only. These synthetics are fine if your body has the ability to properly convert them into T3. Unfortunately, many people find out that their bodies have a hard converting T4 to T3. This could be due to nutrient deficiencies, certain medication, or lack of the enzyme that helps in the conversion process.
  • Triiodothyronine (T3). T3 is the active form of thyroid hormone. This is the thyroid hormone that does most of the work and affects most of the body systems that depend on thyroid hormone.

Common causes of an underactive thyroid:

  1. Hypothalamic dysfunction. Your thyroid gland may be fine but it is not getting adequate stimulation from the hypothalamus and is basically "asleep." In this situation, simply taking a mix of T4 and T3 at the dose that feels best may be adequate. As the hypothalamic function recovers, you may often be able to wean off the thyroid hormone.
  2. Hashimoto's Thyroiditis. In this autoimmune proc, ss your body's immune system attacks and damages the thyroid. This can be diagnosed by a blood test called an "anti-TPO antibody." If the anti-TPO antibody is elevated, you likely have Hashimoto's Thyroiditis and may need to take thyroid supplementation for the rest of your life.
  3. Inadequate conversion of the T4 thyroid hormone to active T3. In this situation, which is very common in fibromyalgia, patients often respond best to therapy with pure T3 hormone. Blood tests are normal despite needing 9-27 mcg a day of T3 thyroid hormone.
  4. Receptor resistance. In this situation, your body is making adequate amounts of thyroid hormone but the areas that they stimulate are very slow to recognize the thyroid hormones' presence. Because of this, it takes a very high level of pure T3 hormone to get a normal response. This problem often resolves over one to two years on the high-dose T3 therapy.

Thyroid Optimization Therapy Consultation

For a free consultation about Thyroid Hormone Optimization Therapy, call 480-839-4131 or fill out a consultation request form located throughout the site. We look forward to speaking with you and seeing if Thyroid Optimization Therapy is a good option for you and your health concerns.

We serve patients in the Phoenix AZ area including Tempe, Chandler, Gilbert, Mesa, Scottsdale, Ahwatukee, Peoria, Glendale, Avondale, and Fountain Hills. All patients always work directly with one of our licensed physicians to ensure patient safety and confidentiality.