Rheumatoid factor interference with the latex agglutination test for fibrin degradation products

Area of Science:

• Clinical Chemistry
• Immunology
• Hematology

Background:

• The latex agglutination test for Fibrin Degradation Products (FDP) is a common clinical tool for diagnosing Disseminated Intravascular Coagulation (DIC).
• Rheumatoid Factor (RF) is known to interfere with certain immunoassays.
• Accurate FDP measurement is crucial for timely and effective patient management.

Purpose of the Study:

• To investigate the extent of Rheumatoid Factor (RF) interference in Fibrin Degradation Products (FDP) latex agglutination tests.
• To evaluate the efficacy of reducing agents in eliminating RF-induced false-positive FDP test results.
• To establish a simple method for differentiating true FDP positivity from RF-mediated false positivity.

Main Methods:

• Sera containing known Rheumatoid Factor (RF) were tested using the FDP latex agglutination assay.
• The effect of reducing agents on the agglutinating capability of RF was assessed.
• Patient sera positive for both FDP and RF were treated with reducing agents and re-tested for FDP.

Main Results:

• 93% of sera containing RF demonstrated positive FDP latex agglutination tests.
• Reducing agents completely abolished the RF agglutinating capability in all tested samples.
• Following reduction, 86% of sera that were initially positive for both FDP and RF became FDP-negative.

Conclusions:

• Rheumatoid Factor (RF) is responsible for a significant number of false-positive FDP latex agglutination tests.
• Treatment of patient sera with reducing agents is an effective and rapid method to distinguish true FDP positivity from RF interference.
• This reduction method can improve the diagnostic accuracy of FDP testing in clinical practice.