The thyroid is a butterfly-shaped gland that lies in front of the windpipe, just below the voice box (larynx). The thyroid gland uses iodine from food to make several hormones that are essential for normal growth, neuronal development, reproduction, and regulation of energy metabolism. Thyroid hormone production is triggered by thyroid-stimulating hormone (TSH) secreted by the pituitary gland.
The three most important hormones regarding thyroid disease and cellular function are:
- Thyroxine or T4, the storage form of thyroid hormone (the majority).
- Triiodothyronine or T3, the active form of thyroid hormone (5 times more active than T4).
- Reverse T3 (rT3), the inactive mirrored form of T3, inhibits T3 function.
While sufficient dietary iodine is important for optimal thyroid function, factors such as other nutrient deficiencies, aging, smoking, genetic susceptibility, environmental chemicals (e.g., “endocrine-disruptors” in some plastics), and certain medications can also affect thyroid health. Hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid) are common conditions that can have devastating health consequences if undiagnosed, but which are easy to identify with simple blood tests.
The thyroid hormones T3 and T4 circulate in blood by reversibly binding to carrier proteins. Although only a very minor amount (< 1%) of T3 and T4 circulates unbound, it is this free hormone fraction that is metabolically active at the tissue level. Measurement of thyroid-stimulating hormone (TSH), free T3, and free T4 is important in proper assessment of thyroid function.
Increased levels of reverse T3 can occur during times of physical stress as well as states of insulin resistance and type 2 diabetes mellitus. Immune system activation, high adrenaline levels, excess free radicals, aging, fasting, psychosocial stress, and prolonged illness will also drive the inactivation of T3 to reverse T3.
Thyroid dysfunction is often due to thyroid autoimmunity, in which case the detection of thyroid antibodies in the blood can help diagnose Graves’ disease or Hashimoto thyroiditis. The Salveo Diagnostics full thyroid workup also includes total T3/T4 and the antibodies to thyroglobulin (anti-Tg) and thyroid peroxidase (anti-TPO).
Thyroid Health Assessment:
- Total T4 & Free T4
- Total T3 & Free T3
- Reverse T3
- Anti-TPO Antibody
- Anti-Tg Antibody