Parathyroid Hormone / PTH (BSB-24), MMab

Summary and Explanation

Parathyroid hormone (PTH), parathormone or parathyrin, is secreted by the chief cells of the parathyroid glands as a polypeptide containing 84 amino acids. It acts to increase the concentration of calcium (Ca2+) in the blood, whereas Calcitonin (a hormone produced by the parafollicular cells (C cells) of the thyroid gland) acts to decrease calcium concentration. PTH acts to increase the concentration of calcium in the blood by acting upon the parathyroid hormone 1 receptor (high levels in bone and kidney) and the parathyroid hormone 2 receptor (high levels in the central nervous system, pancreas, testis, and placenta). PTH half-life is approximately 4 minutes.

Parathyroid Hormone antibody is also useful to distinguish parathyroid hyperplasia/neoplasms from thyroid and metastatic neoplasms. If the patient’s hypercalcemic status is not known, PTH immunohistochemistry is helpful, especially if clear cell parathyroid carcinomas are nonsecretory and there is no abnormality in mineral metabolism. The other instance in which anti-PTH antibodies are useful is in the consideration of parathyroid carcinomas located primarily in the anterior mediastinum. In this situation distinction from primary thymic metastatic carcinomas, non-Hodgkin’s lymphoma and germ cell tumors is necessary.