Thyroid hormones are primarily involved in directing the metabolic activity of cells, and a properly regulated thyroid is therefore essential to a wide array of biochemical processes in the body. Subclinical hypo- and hyperthyroidism can therefore result in symptoms even when hormone levels appear to be normal3, because the abnormal TSH indicates that there is still a disorder in thyroid regulation, and because thyroid hormone activity can be affected by interactions with other hormone systems, particularly estrogens and cortisol, and by some nutritional deficiencies. Management of thyroid dysfunction requires an understanding of these interactions and careful monitoring of treatment with regular thyroid function tests.
TPO = Thyroid Peroxidase
TSH = Thyroid Stimulating Hormone
fT3 = Free T3 (Free Triiodothyronine)
fT4 = Free T4 (Free Thyroxine)