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.
A test for parathyroid hormone (PTH) is done to: 1  Help identify hyperparathyroidism. 2  Find the cause of an abnormal blood calcium level. 3  Check to see whether a problem with the parathyroid glands is causing the abnormal calcium level.igh PTH levels may be caused by: 1  A parathyroid gland growth (hyperplasia) or a parathyroid tumor. 2  A low level of calcium in the blood. 3  Some types of cancer, such as of the lung, kidney, pancreatic, or ovarian cancer.