Pathology tests database

Sample and container requirements

EDTA Plasma

Minimum volume required

4 mL EDTA blood

Special requirements

Specimen should be seperated and frozen within 7 hours of venepuncture. If sample is from an external source specimen must be separated and frozen if unable to deliver within one hour.

Patient preparation

Sent Frozen to referral laboratory

Sample viability

Store frozen at -20oC prior to sending to referral lab

Turnaround time

4 weeks

Reference range

Normal values <5 mg/L.

Clinical guidance

C3d is a useful marker of complement consumption as it is not affected by the acute phase response, unlike C3 which may remain within the normal range despite significant consumption. This test may be clinical useful to determine whether low complement levels indicate active consumption or deficiency. Determining complement consumption can also be used to monitor disease activity in conditions such as SLE Rhematoid arthritis https://sheffieldlaboratorymedicine.nhs.uk/search-test.php?search=2987&testname=C3d%20Levels,%20C3%20Breakdown%20Product

Notes

Serum samples may give falsely elevated levels of C3d, EDTA plasma must be used. specimen referred to Sheffield