Thyroid Hormones

What Are Thyroid Hormones?

The thyroid gland takes iodine from the food we eat and combines it with the amino acid tyrosine to make two thyroid hormones: thyroxine (T4) and triiodothyronine (T3). These hormones are released into the bloodstream and transported throughout the body to regulate metabolism.

T4 is the inactive form of thyroid hormone; it’s produced solely by the thyroid gland. T3 is the active form. The thyroid gland produces about 20% of the T3 in our bodies. Proper thyroid function requires the conversion of T4 to T3 by removing an iodine atom by deiodinase enzymes in the body. Most people have enzymes called deiodinases in organs like the liver, brain, kidneys, and heart, which produce the other 80% by converting T4 into T3, as needed. It is important that T3 and T4 levels are not too high or too low.

Production and release of T3 and T4 are controlled by the hypothalamus, pituitary gland, and thyroid gland. In a healthy body they create a feedback loop that maintains appropriate circulating hormone levels. The amount of T4 produced by the thyroid gland is regulated by the thyroid stimulating hormone (TSH). Transport of these hormones into tissue cells is also critical for activity.

Many factors can impair the conversion of T4 to T3, such as high or low levels of vitamins, minerals, and hormones. This may result in hypothyroidism. Low thyroid or hypothyroidism is a common condition, and many people who have it can take a commercial prescription hormone supplement that contains standardized amounts of T4 and/or T3. These can work well if the patient’s hormone levels remain stable. However, some patients need special strengths or ratios of T3 and T4. There are others whose hormone levels tend to fluctuate regularly, and they need medication that responds to changing needs. Compounding allows for customized dosages and easy dose adjustments based on current test results.

Who May Benefit From Thyroid Hormone Replacement/ Supplementation?

People with hypothyroidism

Hypothyroidism is a common endocrine issue in which the thyroid gland does not produce enough thyroid hormones. It is especially common in women over 60 but can occur in people of all ages. In adults, Hashimoto’s disease is the most common cause of hypothyroidism in industrialized countries. In the rest of the world, iodine deficiency is the most common cause. In Hashimoto’s, the immune system attacks and damages the thyroid. Hypothyroidism can also be caused by radioactive treatment or surgery on the thyroid gland. Problems with the pituitary gland can also cause hypothyroidism by interrupting the feedback loop. Congenital hypothyroidism, present from birth, occurs when the thyroid gland does not develop properly.

How Belmar Can Help

If you’re a clinician interested in prescribing compound medications to your patients, contact us for information on how to get started and to access all of our clinical resources. If you are new to compounding, you may find our page on How to Write a Compounding Prescription helpful. You can also visit our Treatment Options page to find a formulary and learn more about all the medication solutions available from Belmar.