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C4 (Complement C4)

Alternate Name: C4

  | C4 Complement Component

SAL Code:

1968

CPT:

86160

Loinc:

4498-2

Turn Around Time:

1 Day

Setup:

Daily

Units:

mg/dL

Department:

Diagnostic Immunology

Performing Laboratory:

Sherman Abrams Laboratory

Specimen Requirements:

Primary Tube:

SST

Primary Substance:

Serum

Temperature

Period

Stable Ambient:

3 Days

Stable Fridge:

7 Days

Stable Frozen:

28 Days

Rejection Criteria:

Gross hemolysis; lipemia; improper labeling

Clinical Info:

C4 levels are sensitive indicators of lupus disease activity. In hereditary angioedema, the lack of C1 esterase inhibitor allows unopposed lysis of C2 and C4 by C1 esterase, so C4 levels will be low. C4 deficiency has been described in association with a clinical SLE-like disease but with absence of LE cells and variable immunoglobulin or C3 deposits in the skin biopsy, and with Henoch-Schönlein purpura or glomerulonephritis.

Additional Information:

Quantitation of C4 is used to detect individuals with inborn deficiency of this factor or those with immunologic disease in whom hyper catabolism of complement causes reduced levels. These diseases include lupus erythematosus, serum sickness, certain glomerulonephritides, chronic active hepatitis, and others.

Sample Collection:

Collect patient samples using standard phlebotomy techniques. Click here for additional collection instructions.

Test Limitations:

Total hemolytic activity (CH50), C3, and C4 are frequently decreased in a variety of conditions producing immune complexes.

Test Information:

Components:

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