CPT® Code 86161

The CPT® Code 86161 refers to a laboratory test that measures the functional activity of complement components in the blood. Complement factors are crucial proteins that play a significant role in the immune system, particularly in the clearance of immune complexes from the bloodstream. The complement system operates through a cascade mechanism, leading to the formation of the membrane attack complex (MAC), which is essential for both innate and adaptive immune responses. This process involves the attachment of complement proteins to the cell membrane of pathogens, resulting in the lysis or rupture of these cells, thereby aiding in the elimination of infections. Individuals exhibiting low levels of complement functional activity are at an increased risk for infections due to the compromised ability of their immune system to respond effectively. To perform this test, a blood sample is collected through a venipuncture, which is a separately reportable procedure. The complement functional activity is then assessed using specific methodologies, predominantly through a quantitative hemolytic assay. The code 86161 should be reported for each complement functional activity tested, including components 1, 6, 7, 8, 9, and the C1-esterase inhibitor functional activity.