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Test Code BLOD1451 C4b Binding Protein

Additional Codes

Esoterix Test Code: 300160




Useful in the investigation of patients with a history of thrombosis.

Performing Laboratory

Esoterix Laboratories

Specimen Requirements

Specimen Type: Double-spun sodium citrate plasma

Container/Tube: Full blue top (3.2% sodium citrate)

Specimen Volume: 1.0 mL plasma

Specimen Minimum Volume: 0.5 mL plasma (does not allow repeat testing)

Collection Instructions:

1. Immediately after draw, invert tubes several times to mix blood with additive.

2. Send specimen in original tube.

3. If there is a delay in transport of >4 hours, specimen must be double-centrifuged to prepare a platelet-free plasma specimen as follows:

a. Immediately centrifuge at 3,200 rpm for 15 minutes.

b. Carefully remove plasma from cells avoiding platelet/buffy coat, and transfer plasma into a plastic tube.

c. Centrifuge plastic tube at 3,200 rpm for 15 minutes.

d. Carefully remove top portion of plasma and transfer plasma into a plastic tube leaving approximately 250 mcL in bottom to discard.

e. Double-centrifuged plasma should be aliquoted (0.5 mL-1 mL each) into clearly labeled plastic tubes. (Glass vial is not acceptable.)

f. Specimens should be frozen at <-40° C, if possible, and sent together in same container with at least 5 lbs of dry ice. Specimens must arrive at Esoterix in a frozen state.

Additional Information: Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

Specimen Transport Temperature

Whole blood-Ambient

Specimen Stability


Specmen Type Temperature Time
Whole Blood (unspun) Ambient 4 hours
Plasma Na Citrate (double spun) Frozen 30 days


Day(s) Test Set Up



Turnaround Time: 1-6 days



Test Classification and CPT Coding