Parathyroid Hormone (PTH) Basic Information Definition • Hyperparathormonemia: Increased circulating concentration of parathyroid hormone • Hypoparathormonemia: Decreased circulating concentration of parathyroid hormone Synonym(s) Parathormone Typical Normal Range (US units; SI units) Less than 4.0 pmol/L or 40 pg/mL Physiology PTH is a polypeptide hormone secreted by the parathyroid gland that regulates the metabolism of calcium and phosphorus in the body. PTH acts on parathyroid hormone receptor in bones, the kidneys, and small intestine to regulate serum calcium concentration. In bone, PTH binds directly to osteoblasts, which stimulates them to increase their expression of receptor activator of nuclear factor kappa B ligand (RANKL), which can bind to osteoclast precursors containing RANK. The binding of RANKL to RANK stimulates these precursors to fuse, forming new osteoclasts which ultimately enhance the resorption of bone, resulting in increased serum calcium concentration. In the kidney, PTH enhances active reabsorption of calcium from the distal tubules and the thick ascending limb of the loop of Henle. Additionally, PTH upregulates 25-hydroxyvitamin D3 1-alpha-hydroxylase, the enzyme responsible for 1-alpha hydroxylation of 25-hydroxy vitamin D, converting vitamin D to its active form. This activated form of vitamin D affects the absorption of calcium in the intestine via calbindin. PTH is inactivated and degraded by the kidneys and liver. Increased concentrations of vitamin D and free calcium inhibit synthesis of PTH. Causes of Abnormally High Levels Increased circulating concentrations are typically due to increased production of PTH by either neoplastic cells or nonneoplastic parathyroid gland hyperplasia.< div class='tao-gold-member'> Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: Aggressive Stallion Behavior Aflatoxin Toxicosis Biliary Atresia Black Widow Spider Toxicosis Stay updated, free articles. Join our Telegram channel Join Tags: Clinical Veterinary Advisor The Horse Jul 24, 2016 | Posted by admin in SMALL ANIMAL | Comments Off on Parathyroid Hormone (PTH) Full access? Get Clinical Tree
Parathyroid Hormone (PTH) Basic Information Definition • Hyperparathormonemia: Increased circulating concentration of parathyroid hormone • Hypoparathormonemia: Decreased circulating concentration of parathyroid hormone Synonym(s) Parathormone Typical Normal Range (US units; SI units) Less than 4.0 pmol/L or 40 pg/mL Physiology PTH is a polypeptide hormone secreted by the parathyroid gland that regulates the metabolism of calcium and phosphorus in the body. PTH acts on parathyroid hormone receptor in bones, the kidneys, and small intestine to regulate serum calcium concentration. In bone, PTH binds directly to osteoblasts, which stimulates them to increase their expression of receptor activator of nuclear factor kappa B ligand (RANKL), which can bind to osteoclast precursors containing RANK. The binding of RANKL to RANK stimulates these precursors to fuse, forming new osteoclasts which ultimately enhance the resorption of bone, resulting in increased serum calcium concentration. In the kidney, PTH enhances active reabsorption of calcium from the distal tubules and the thick ascending limb of the loop of Henle. Additionally, PTH upregulates 25-hydroxyvitamin D3 1-alpha-hydroxylase, the enzyme responsible for 1-alpha hydroxylation of 25-hydroxy vitamin D, converting vitamin D to its active form. This activated form of vitamin D affects the absorption of calcium in the intestine via calbindin. PTH is inactivated and degraded by the kidneys and liver. Increased concentrations of vitamin D and free calcium inhibit synthesis of PTH. Causes of Abnormally High Levels Increased circulating concentrations are typically due to increased production of PTH by either neoplastic cells or nonneoplastic parathyroid gland hyperplasia.< div class='tao-gold-member'> Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: Aggressive Stallion Behavior Aflatoxin Toxicosis Biliary Atresia Black Widow Spider Toxicosis Stay updated, free articles. Join our Telegram channel Join Tags: Clinical Veterinary Advisor The Horse Jul 24, 2016 | Posted by admin in SMALL ANIMAL | Comments Off on Parathyroid Hormone (PTH) Full access? Get Clinical Tree
