C4 binding protein-994

Test info

C4 binding protein

Confirmation and characterization of protein S (PS) deficiency: C4b-binding protein elevates as an acute phase protein that may lead to enhanced protein S binding and decreased free protein S levels.


Sodium citrate (Na cit) plasma
2.0 mL
1.0 mL
  • Do not draw from an arm with a heparin lock or heparinized catheter
  • Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.
  • Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.
  • The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood.
  • A discard tube is not required prior to collection of coagulation samples, except when using a winged blood collection device (ie, "butterfly"), in which case a discard tube should be used. When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes.
  • Any tube containing an alternate anticoagulant should be collected after the blue-top tube.
  • Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes.

Prepare platelet poor plasma.

  1. Centrifuge for 10 minutes and carefully remove 2/3 of the plasma using a plastic transfer pipette, being careful not to disturb the cells.
  2. Deliver to a plastic transport tube, cap, and recentrifuge for 10 minutes.
  3. Use a second plastic pipette to remove the plasma, staying clear of the platelets at the bottom of the tube.
  4. Transfer the plasma into a Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp)
  5. Freeze immediately and maintain frozen until tested

Frozen (strict)

Ambient - 8 hours


LabCorp - Esoterix Coag (500452): R-NX
4 - 8 days

Enzyme-linked immunosorbent assay (ELISA)

Clinical and Interpretive info


C4bBP levels range from 60 - 150%

  • Adult levels of C4bBP are generally reached at six months of age
  • Levels are generally undetectable in the neonate