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Complement C3, Serum

Test ID:

704797

CPT code:

86160

Synonyms:

C3 (β1C/β1A Globulin)

C3 Complement

Clinical Use:

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. These include lupus erythematosus, chronic active hepatitis, certain chronic infections, poststreptococcal and membranoproliferative glomerulonephritis, and others.

Test Information:

C3 comprises about 70% of the total protein in the complement system and is central to activation of both the classical and alternate pathways. Increased levels are found in numerous inflammatory states as an acute phase response. CH50 (total complement hemolytic activity), C3 and/or C4 may be decreased in cases of systemic lupus erythematosus, especially in cases with lupus nephritis, acute and chronic hypocomplementemic nephritis, subacute bacterial endocarditis, DIC, and partial lipodystrophy (with associated nephritis-like activity in serum.) In cases of disseminated intravascular coagulation, plasmin attacks C3 directly, and C3 levels have been found low in the hemolytic uremic syndrome form of disseminated intravascular coagulation (DIC). Cases of hereditary C3 deficiency, while rare, have been reported and are characterized clinically by recurrent infections (eg, pneumonia, meningitis, paronychia, impetigo). Pathogenic bacteria causing infections in these cases have included both gram-positive and gram-negative organisms. C3 levels have also been found deficient in cases of uremia, chronic liver diseases, anorexia nervosa, and celiac disease.

Specimen Type:

Serum (preferred) or plasma

Requested Volume:

1 mL (adult), 0.5 mL (pediatric)

Container Type:

Red-top tube, gel-barrier tube, or green-top (heparin) tube.

Collection:

Remove serum or plasma within 45 minutes and transfer to a plastic transport tube. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.