D-Dimer : 1000260

Message
The plasma aliquot must remain frozen. Freeze thaw cycle will adversely affect specimen integrity. CRITICAL FROZEN: Separate specimens must be submitted when multiple tests are ordered.

Test Code
DDM or 1000260

Alias/See Also
D-dimer

CPT Codes
85379

Instructions
Blue top tube, 3.2% sodium citrate.
• Obtain venous blood by clean venipuncture. Avoid slow-flowing draws and/or traumatic venipunctures as either of these may result in an activated or clotted specimen. Do not use needles smaller than 23 gauge. Do not leave the tourniquet on for an extended length of time before drawing the sample.
• A pilot tube (non-additive or light blue tube) before drawing coagulation specimens in light blue vacuum tubes is only necessary when using a butterfly blood collection set as this will cause reduced draw volume in the first tube. Discard the pilot tube.
• Fill light blue tubes as far as vacuum will allow and mix by gentle inversion. Exact ratio of nine parts blood to one part anticoagulant must be maintained. Inadequate filling of the sample tube will alter this ratio and may lead to inaccurate results. Patients who have hematocrit values above 55 percent should have the anticoagulant adjusted to maintain the 9:1 ratio. Use the following formula to determine the amount of anticoagulant to use: [(100 – Hct) / (595 – Hct) ]* total volume = amount of anticoagulant required.
• After collecting the blood, examine the tube to ensure that it is filled to within 90% of the fill line.
• Note: Specimens containing heparin should not be used for coagulation studies. If possible, stop heparin therapy before the draw to avoid contamination. Heparin interferes with most clotting assays. If heparinized line must be used to obtain the sample, flush line with 5mL saline and discard the first 5 mL of blood drawn into a syringe, or 6 “dead space” volumes of the line.

Transport Container
If sending Plasma:  Centrifuge the blue top tube at a rate of speed to yield platelet poor plasma (<10,000 /uL), immediately remove only the top two-thirds of the platelet-poor plasma from the specimen using a plastic-transfer pipet (use of glass-transfer pipets may result in activation and/or clotting of the plasma) and transfer citrated plasma (Min. 0.5 mL) into a standard transport tube, and freeze the aliquot.

If sending Whole Blood: Specimen must be tested within 24 hours of draw. Submit citrated whole blood.  Do not centrifuge and do not refrigerate.  Send ambient only.

Specimen is stable at room temperature for up to 24 hours. If testing cannot be completed within 24 hours, the specimen must be centrifuged and processed according to the above plasma instructions and plasma aliquot sent frozen.

Transport Temperature
Plasma: Frozen.
Whole Blood:  Ambient within 24 hours of draw.

Specimen Stability
Ambient:  Whole blood 24 hours; After separation from cells: Refrigerated: 24 hours; Frozen: 4 weeks

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Tubes not filled within 90% of the fill line will be rejected by the lab.

Methodology
Immunoturbidimetric

Setup Schedule
Sunday - Saturday

Report Available
1 day

Reference Range
0.00-0.58 mg/L FEU
Studies indicate that using a cut-off of 0.5 mg/L FEU gives this assay a negative predictive value of 98% for Pulmonary Embolism and Deep Vein Thrombosis.

Clinical Significance
The D-Dimer assay is intended for use as an aid in the diagnosis of venous thromboembolism (VTE), deep vein thrombosis (DVT), and pulmonary embolism (PE).

Coagulation activation results in the cleavage of fibrinogen to fibrin monomer. The fibrin monomers spontaneously aggregate to fibrin and are cross-linked by Factor XIII to produce a fibrin clot. In response to the coagulation process, the fibrinolytic system is activated, resulting in the conversion of plasminogen into plasmin, which cleaves fibrin (and fibrinogen) into the fragments D and E. Due to cross-linkage between D-domains in the fibrin clot, the action of plasmin releases fibrin degradation products with cross-linked D-domains. The smallest unit is D-Dimer. Detection of D-Dimers, which specifies cross-linked fibrin degradation products generated by reactive fibrinolysis, is an indicator of coagulation activity. Fibrin degradation products are not consistently “D-Dimer,” but are a mixture of fragments and complexes of different molecular weights containing the D and E domains. An association between a certain mixture or molecular weight and the clinical condition has not been demonstrated. The in-vivo half life of D-Dimer is approximately 8 hours. Elevated D-Dimer levels are observed in all diseases and conditions with increased coagulation activation, e.g., thromboembolic disease, DIC, myocardial infarction, malignant diseases, obstetrical complications, and surgery. For the diagnosis of DIC, a scoring system has been suggested in which elevated D-Dimer levels represent the major indicator of DIC.

Performing Laboratory
med fusion



The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.