Days Set Up
Daily, 24 hrs
Analytic Time

2 hours

MiChart Code
C4 Complement
Soft Order Code

Test Updated:


Complement C4
Fourth Component of Complement

Looking to order a test?

We’ve provided helpful links to make ordering easy.

Find a Requisition

All specimens should be accompanied by a requisition.

Submitting Specimens

Learn about how to properly label and where to ship specimens.

Order Kits and Supplies

MLabs provides all the supplies necessary for the collection of specimens.

Test FAQ

Visit our provider FAQ and learn about common questions to ordering tests.

Test Overview

Test Methodology


Test Usage

C4 is decreased when classical pathway of complement is hyperactivated. It is usually decreased in hypergammaglobulinemia, cryoglobulinemia, inborn C4 deficiency, active SLE, serum sickness, SBE, chronic active hepatitis, acute glomerulonephritis and rheumatoid arthritis, as well as in hereditary angioneurotic edema.

Reference Range

Adult: 13-60 mg/dl

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Specimen Requirements

Collection Onsite

Collect specimen in an SST tube. .

Collection Offsite

Collect specimen in an SST tube. Centrifuge, aliquot serum into a plastic vial and refrigerate up to 48 hours.

Yellow Top Tube
Normal Volume
0.5 mL serum
Minimum Volume
0.25 mL serum

Billing Information

CPT Code
Pro Fee Code

Have More Questions?

Explore our helpful billing resources:

Our High Standard

Quality that sets us apart

As the reference laboratory division of Michigan Medicine's Department of Pathology, MLabs shares the institution's commitment to applying established quality principles to clinical laboratory testing. Like other large organizations in complex, consequential fields, we rely on an established approach to monitor quality throughout the testing process.