Use

This test is used for diagnosing C9 deficiency and investigating patients with low total hemolytic complement levels. The complement system is critical to immune defense and involves multiple pathways, including the classical, alternative, and lectin pathways, which result in the formation of the membrane attack complex (MAC). Deficiency in late complement proteins like C9 can increase susceptibility to infections, particularly neisserial infections, though many C9 deficient patients can be asymptomatic.