Orosomucoid


Orosomucoid or alpha-1-acid glycoprotein is an acute phase protein found in plasma. It is an alpha-globulin glycoprotein and is modulated by two polymorphic genes. It is synthesized primarily in hepatocytes and has a normal plasma concentration between 0.6-1.2 mg/mL. Plasma levels are affected by pregnancy, burns, certain drugs, and certain diseases, particularly HIV.
The only established function of ORM is to act as a carrier of basic and neutrally charged lipophilic compounds. In medicine, it is known as the primary carrier of basic drugs, steroids, and protease inhibitors. Aging causes a small decrease in plasma albumin levels; if anything, there is a small increase in alpha-1-acid glycoprotein. The effect of these changes on drug protein binding and drug delivery, however, appear to be minimal. AGP shows a complex interaction with thyroid homeostasis: ORM in low concentrations was observed to stimulate the thyrotropin receptor and intracellular accumulation of cyclic AMP. High AGP concentrations, however, inhibited TSH signalling.
Alpha-1-acid glycoprotein has been identified as one of four potentially useful circulating biomarkers for estimating the five-year risk of all-cause mortality.
Orosomucoid increases in amount in obstructive jaundices while diminishes in hepatocellular jaundice and in intestinal infections.