Quantitation of C3 is used to detect individuals with inborn deficiency of this factor or those with immunologic disease in whom complement is consumed at an increased rate. Increased levels are found in numerous inflammatory conditions as an acute phase reactant. Acquired deficiency is encountered in active lupus and glomerulonephritis. May be decreased in immune complex disease, serum sickness, chronic active hepatitis, inborn C3 deficiency and subacute bacterial endocarditis (SBE).
Adult: 83-240 mg/dl
Detects both biologically active and inactive C3.
- Complement C3
- Third Component of Complement
- C3 COMPLEMENT
Collect specimen in an SST tube. Centrifuge, aliquot serum into a plastic vial and refrigerate up to 8 days or freeze for longer storage.
C3 comprises about 70% of the complement system and is utilized in both the classical and alternate pathways of complement activation. Increased levels are found in numerous inflammatory states as an acute phase reactant. CH50 (total complement hemolytic activity), C3 and/or C4 may be decreased in cases of systemic lupus erythematosus, especially in cases with lupus nephritis, in acute and chronic hypocomplementemic nephritis, SBE, disseminated intravascular coagulation (DIC), and partial lipodystrophy (with associated nephritis-like activity in serum). Cases of hereditary C3 deficiency, while rare, have been reported and are characterized clinically by recurrent infections (e.g., pneumonia, meningitis, impetigo). Low C3 levels have also been found in cases of uremia, chronic liver diseases, anorexia nervosa, and coeliac disease.