Yale New Haven Hospital

Department of Laboratory Medicine
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C3 + C4 complement component

Lab Section: 



Lab Location: 

Main Lab

Test ID: 








2 days

Specimen Requirements: 

Collection: 5.0 mL Blood in a Gold Top Tube.
Pediatric volume: 1 mL.
Do not allow specimen to clot at refrigerated temperature.
Unacceptable conditions: Grossly hemolyzed specimens.
Stability: After separation from cells: Ambient 24 hours, Refrigerated: 3 days; Frozen: 3 days



Clinical Indications: Diminished serum concentrations of C3 and C4 are observed primarily in active systemic lupus erythematosus (SLE), in forms of membrane proliferative glomerulonephritis and in immune complex diseases (serum sickness). In the case of SLE the serum concentrations of the complement factors reflect the activity of the disease. Diminished C3 values occur in acute glomerulonephritis and in membrane proliferative glomerulonephritis whereas isolated diminished levels of C4 can occur in hereditary angloedema (HAE) and in cases of autoimmune hemolytic anemia. Both complement components react as acute-phase proteins and may therefore show elevated serum concentrations in patients with inflammatory diseases. Hereditary deficiency states of both complement factors have been reported.

Tests in this Panel: 

C3: Reference Interval >1 year 81-145 mg/dL


C4: Reference Interval >1 year 16-39 mg/dL


Reference ranges have not been established for children less than 1 year old.

CPT Code(s): 


Last Changed: 

8/24/2017 9:48:00 AM

Last Reviewed: 

8/24/2017 9:48:09 AM