Test Name

C4

Test Code

272

Unit

mg/dL

Station

Chemistry

Synonym Name/Abbreviation

Complement C₄

CPT Code

86160

Performing Facility

American Medical Labs, Herzliya
Pituah

Analyzer

Roche cobas 6000

Test Method

Immunoturbidimetric assay

AML Preferred Tube

Serum

Storage Instructions

Refrigerated.

Stability:

2 days 15 to 25 ^oC

2 days 2 to 8 ^oC

Min. Volume

1 mL

Comments

C4 is an acute phase protein, which production raises during
inflammatory processes.

Turn-Around-Time

One day

Intended Use

The main use of C4 quantitation is in assessing the course of
hypocomplement conditions:

to detect individuals with inborn deficiency of this factor
or those with immunologic disease in whom  complement is consumed at
increased rate. These diseases include lupus erythematosus, certain
glomerulonephritis, chronic active hepatitis, dermatomyositis, angioedema,
Henoch-Schonlein purpura. Certain bacterial and viral infections are
associated with a fall in C4 (streptococcal and staphilococcal sepsis,
viral meningitis).

C4 is elevated in systemic infections and physiological
states like pregnancy

Limitations

Monoclonal gammopathies , IgA or IgM type may cause
unreliable results.

Patient Preparation

No patient preparation.

Reasons for Rejection

Excessive lipemia (>250 mg/dL) and rheumatoid factors
(>200 IU/mL) significantly increase the apparent C₄
concentration.

Adult Reference Ranges

10 – 40
mg/dL