Leucine-rich alpha-2-glycoprotein is an acute phase protein with levels elevated in patients with bacterial infections; interestingly, during the inflammatory response, LRG1 levels are not correlated with CRP levels. LRG1 binds cytochrome c, an initiator/amplifier of programmed cell death (apoptosis), and by binding cytochrome c, is thought to play a role in cell survival.

LRG1 is a biomarker associated with several cancers, including non-small cell lung cancer, colorectal cancer, and pancreatic cancer. Recent studies have shown it is three-fold more abundant in ovarian cancer serum compared to non-cancer control serum. LRG1 levels are only moderately correlated with CA125 levels.

Elevated levels of LRG1 in cerebral spinal fluid are being studied as markers for the early diagnosis of Parkinson's disease and progressive supranuclear palsy. In normal plasma LRG1 has a concentration of 21-50 ug/ml