Other cells that contain hemoglobin include the A9 dopaminergic neurons in the substantia nigra, macrophages, alveolar cells, and mesangial cells in the kidney. In these tissues, hemoglobin has a non-oxygen-carrying function as an antioxidant and a regulator of iron metabolism.
The opposite is hypothyroidism, when the thyroid gland does not make enough thyroid hormone. Graves' disease is the cause of about 50% to 80% of case of hyperthyroidism in the United States. Other causes include multinodular goiter, toxic adenoma, inflammation of the thyroid, eating too much iodine, and too much synthetic thyroid hormone.
TSH that is âsuppressedâ or below normal, is considered evidence of hyperthyroidism. Currently, the reference range runs from around 0.5 to 5.0. Levels above 3.0 are evidence of possible hypothyroidism, and levels below 0.5 are evidence of possible hyperthyroidism.