Parathyroid hormone (1-34) (bovine) is a parathyroid hormone (PTH) receptor agonist. It increases calcium and inorganic phosphate levels in the serum of young rats. Parathyroid hormone (PTH) is the most important endocrine regulator of calcium and phosphorus concentration in extracellular fluid, which is secreted by the chief cell of the parathyroid glands as a polypeptide containing 84 amino acids.