Test BackgroundLowered C3 or C4 levels may be due to excessive consumption of the complement cascade, as seen in immune complex-mediated disease, such as SLE with associated renal disease, or cryoglobulinaemic nephritis. May indicate disease flare or aid prognosis. Also, components can be low due to genetic/acquired defects. Commonest cause of low C3 and C4 is sample degradation. Raised levels may indicate an acute phase response.
|C3||:|| 0.7-1.7 g/L
Sample Required SST (gold top)
Sample Volume 5-10 mL (1 mL serum)
Turnaround Time 4 days