85379

Fibrin degradation products (FDP), quantitative

CPT code 85379 describes a quantitative laboratory analysis used to measure the concentration of fibrin degradation products (FDP) in a patient's blood. FDPs are chemical fragments produced by the body whenever a blood clot (fibrin) is broken down by the enzyme plasmin through the process of fibrinolysis. Under normal physiological conditions, clot formation and clot dissolution exist in a regulated balance. However, when excessive clotting occurs within the vascular system, such as in disseminated intravascular coagulation (DIC), deep vein thrombosis (DVT), or pulmonary embolism (PE), the subsequent activation of the fibrinolytic system leads to an elevation in circulating FDP levels. The quantitative assay provides a numerical value, typically expressed in micrograms per milliliter, allowing clinicians to assess the severity of the fibrinolytic activity. This test is technically distinct from the D-dimer assay (CPT 85378), as FDP measurements encompass fragments of both fibrin and fibrinogen, whereas D-dimer specifically measures cross-linked fibrin degradation. The procedural workflow involves a venipuncture to collect a serum or plasma sample, which is then subjected to specialized immunologic techniques such as latex agglutination or Enzyme-Linked Immunosorbent Assay (ELISA). The resulting data is critical for diagnosing life-threatening coagulopathies and monitoring the efficacy of thrombolytic therapies. Higher than normal levels are highly suggestive of systemic activation of the coagulation and fibrinolytic cascades, necessitating urgent clinical intervention and further diagnostic workup to identify the underlying pathology.

Clinical Indications

  • Diagnosis of Disseminated Intravascular Coagulation (DIC)
  • Suspected pulmonary embolism (PE)
  • Suspected deep vein thrombosis (DVT)
  • Monitoring of fibrinolytic or thrombolytic therapy
  • Evaluation of pregnancy complications such as abruptio placentae or preeclampsia
  • Assessment of hypercoagulable states associated with malignancy
  • Evaluation of liver disease affecting coagulation factor clearance
  • Post-surgical monitoring for thromboembolic events

Procedure Steps

  1. Perform venipuncture to obtain a whole blood sample, typically using a tube containing a specialized anticoagulant or clot activator depending on the laboratory protocol.
  2. Centrifuge the blood sample to separate the serum or plasma from the cellular components.
  3. Prepare the reagents for the quantitative assay, such as anti-FDP antibody-coated latex particles or ELISA plates.
  4. Mix the patient's sample with the reagents to initiate the antigen-antibody reaction.
  5. Measure the resulting turbidity, light scattering, or colorimetric change using an automated analyzer.
  6. Calculate the concentration of FDPs by comparing the reaction measurement against a known standard calibration curve.
  7. Review and validate the numerical results before recording them in the patient's electronic health record.

Coding Guidelines

  • Code 85379 is specific to the quantitative measurement of FDP; if the test is semi-quantitative or qualitative, use code 85380.
  • Do not report 85379 in conjunction with 85378 (D-dimer quantitative) unless the laboratory is performing both distinct assays for separate clinical indications.
  • The collection of the specimen (e.g., 36415) is not included in the laboratory fee and should be billed separately if performed in an office-based setting.
  • Ensure that the medical documentation supports the necessity of a quantitative measurement over a qualitative screen.
  • Check for National Correct Coding Initiative (NCCI) edits if billing alongside other coagulation factors or hematology profiles.

Associated ICD-10 Codes