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How to Measure Fibrin

Fibrin is a blood protein produced during the final stage of the coagulation cascade in response to bleeding. Arranged in long, fibrous chains, Fibrin molecules form a mesh at the bleeding site that entangles blood platelets, which eventually hardens to form the clot. However, this complex system sometimes goes awry to cause clotting disorders. When deep vein thrombosis, pulmonary embolisms or disseminated intravascular coagulation are suspected, Fibrin production is often assessed via D-dimer, a blood protein produced by Fibrin as the body breaks down the blood clot. Results from a D-dimer test can now be read in less than 20 minutes.

Things You'll Need

  • FDA-Approved Rapid Whole blood Agglutination D-dimer test kit
  • Watch or clock with a second hand or timer
  • Pippette
  • Three pipette tips
  • Test tube holder
  • Gloves
  • Whole blood sample for testing
  • Whole blood sample known to be D-dimer negative
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Instructions

  1. Agglutination Testing

    • 1

      Bring reagents supplied in a test kit to room temperature for at least 20 minutes. Mix the blood samples completely. Do not allow the cells to settle out. Blood is composed of multiple components that must be in suspension for correct test results. Place the test tube of blood in test tube rack. Remove one agglutination tray from the test kit. The tray will have two wells: One marked "Negative Control Well" and one marked "Test."

    • 2

      Pipette 10 microliters of the blood sample into each test well located on the agglutination tray, using a fresh pipette tip for each sample in order to avoid contamination. Discard tips into a biohazard container.

    • 3

      Add one drop of the negative control reagent to the control well. Add one drop of the test reagent to the test well. Stir each well with a stir rod contained in the kit for three to five seconds using a separate rod for each well. Ensure that the reagent is spread across the entire surface of the well. Discard the stirrers in a biohazard container.

    • 4

      Mix the entire agglutination tray with a gentle rocking motion for two minutes. Compare the two wells.

    • 5

      The test is positive if the test well shows any sign of agglutination or clumping. The negative well should show no signs of agglutination when compared to the test well. If it does, the test is invalid.

    Quality Control

    • 6

      Perform quality control testing if your sample yielded a positive results. Follow the same procedure for testing the unknown. However, for this control sample, use a whole blood sample that is known to be D-dimer negative. This steps ensures that the sample was not contaminated and that the reagents are active.

    • 7

      Pipette 10 microliters of the D-dimer negative whole blood into both the negative control well and the test well of a new agglutination tray.

    • 8

      Add one drop of the positive control reagent to the test well only. The test well should show clear signs of agglutination when compared to the negative control well. If it does not, this invalidates the results and could mean a failure of reagents. The entire test should be performed again, including the quality control test. If the quality control test yields the same results, new reagents should be used for future testing.

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