The thyroid gland is located in the lower part of the neck. It secretes two essential thyroid hormones: triiodothyroine (T3) and thyroxine (T4). These hormones regulate cell metabolism. They promote optimal growth, development, function and maintenance of all body tissues. They are also critical for nervous, skeletal and reproductive tissue as well as regulating body temperature, heart rate, body weight and cholesterol.
The normal thyroid gland secretes all of the circulating T4 and about 20% of the circulating T3. The T4 made by the thyroid gland circulates throughout the body and is converted into T3 and a tiny amount of reverse T3 in the kidneys, brain and fat tissue. Most of the biological activity of thyroid hormones is due to T3. Reverse T3 has no action on the cell except it binds to T3 receptors blocking the action of T3. In normal thyroid function, however, T3 dominates and reverse T3 is not a problem.
A reduction in the conversion of T4 to T3 or a decreased production by the thyroid gland may lead to hypothyroidism. The synthesis and secretion of thyroid hormones is influenced by a hormone released by the pituitary gland called thyroid-stimulating hormone (TSH). The activity of the thyroid gland is regulated by a negative feedback loop. Therefore, if levels of T3 and T4 are high, the level of TSH will go down and if the levels of T3 and T4 are low, the level of TSH will go up.
Hypothyroidism is characterized by a generalized reduction in metabolic function that most often manifests itself as slowing of physical and mental activity. The most common signs and symptoms of hypthyroidism are: weight gain, fatigue, lethargy, sleepiness, cold hands and/or feet, low body temperature, depression/anxiety, constipation, headache, menstrual problems, reduced sex drive, hair loss, swollen eye lids and general fluid retention, poor memory and concentration and dry skin, hair and/or nails.
Thyroid Hormone Replacement
Thyroid replacement is one of those areas that is greatly benefited by compounding. Therapy can be precisely adjusted to each patient's needs. Specific strengths can be created. Combinations of T3 and T4 can be tailored to the patient's needs. Even dessicated thyroid can be formulated in a strength specific to each patient. Capsules can be created that have an extended release delivery system to help decrease the surge of hormones associated with immediate release commercial tablets. This can help with tolerability. Capsules are created using hypoallergenic ingredients.