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CH50 – a functional assay
| • | measure the ability of the serum to lyse antibody-coated erythrocytes and reflects the activity of all complement components |
| • | the CH50 depends on intact and functional classic and alternative pathways, resulting in effective target lysis |
| • | decreased CH50 levels suggest either: 1) depletion of complement proteins by an immune-mediated process; or 2) inherited deficiency of an individual protein |
| • | low levels of C3 and C4 suggest an immune mechanism |
| • | an extremely low CH50 in the presence of relatively normal C3 and C4 suggests a genetic complement deficiency, with C2 being most common |
| • | (deficiency of C1, C4, and C2 are associated with SLE, glomerulonephritis and nonspecific vasculitis) |
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