Complement 4 (C4)

Preferred Specimen(s) 0.5 mL Serum

Instruction

Overnight fasting is preferred.
Serum should be separated immediately from clot.

Transport Container Plastic screw cap vial

Transport Temperature Refrigerated 1 week

Reject Criteria Grossly hemolysed specimen

Methodology Nephelometry

Clinical Significance C4 is critical to activation of the classical pathway. Concentrations of C4 are decreased in patients with systemic lupus erythematosus (SLE), immune complex disease, and hereditary angioedema. Congenital absence of C4 places such patients at increased risk of bacteremia, especially infections by S. pneumoniae.