New Immunoturbidimetric D-Dimer
Beginning August 4, 2003, the core laboratory will offer a new quantitative immunoturbidimetric D-dimer assay. This assay will replace the manual semi-quantitative latex agglutination assay currently used. The new quantitative assay can be used for exclusion of deep venous thrombosis or pulmonary embolism.

The reference range is <0.5 ug/ml FEU (fibrinogen equivalent units)

Specimen Requirements: 0.5 ml citrated plasma (Blue top tube). The test is available 24 hours a day, 7 days a week. Turn around time is 1 hour.

Several points are important in ordering D-dimer tests for exclusion of DVT/PE:
1. Most D-dimer testing has been done in outpatient or emergency department settings and the test is much less useful in hospitalized patients.
2. A negative D-dimer can be used to exclude PE in those patients with a low pre-test probability or in patients with a low-to-moderate pretest probability and a non-diagnostic ventilation/perfusion scan (ACEP Clinical Policies Committee).
3. The D-dimer test should not be used for patients on anti-coagulation therapy (heparin or warfarin) as these medications may decrease circulating D-dimer levels and lead to a false negative result.

ACEP Clinical Policies Committee and the Clinical Policies Subcommittee on Suspected Pulmonary Embolism. Clinical Policy: critical issues in the evaluation and management of adult patients with suspected pulmonary embolism. Annals of Emergency Medicine 2003;41:257-270.

Questions can be directed to Nancy Rosenthal, M.D., phone 384-8751.