This test card is used for quantitative determination of parathyroid hormone in human serum, plasma or whole blood in vitro. Parathyroid hormone (PTH) is synthesized in parathyroid gland and secreted into blood. The complete PTH is a single polypeptide chain containing 84 amino acids with a molecular weight of about 9500 daltons. The selective determination of intact parathyroid hormone can be directly used to determine the secretion ability of parathyroid gland. PTH in combination with vitamin D and calcitonin mobilizes calcium and phosphorus in the skeletal system, promotes calcium absorption in the small intestine and increases phosphorus excretion in the kidney. The interaction between PTH and calcitonin ensures the stability of blood calcium concentration. High blood calcium concentration inhibited PTH secretion, while low blood calcium concentration promoted PTH secretion. PTH secretion is affected by parathyroid dysfunction, which will lead to the increase or decrease of blood calcium concentration (hypercalcemia and hypocalcemia).