[Discrepancy between two methods of D-dimers measurement: one case of human anti-mouse antibody interference]

Quantification of D-dimers is the major biometry step in the diagnostic of an episode of the venous thromboembolic disease. The measurement of D-dimers can be performed with ELISA or immunoturbidimetric methods suited to emergency, using a mouse monoclonal antibody as capture and/or revelation antibody. Therefore, the presence in patient's plasma of human antibody mouse (HAMA) that binds the mouse antiglobulin used in immunoassays can lead to false negative or false positive results. In a young woman presenting repetitive thoracic pain suggestive of a pulmonary embolism, a major discrepancy was found between one result of D-dimers above the cut-off with an immunoturbidimetric method (STA Liatest D-DI; Diagnostica Stago) and one result below the cut-off with a sandwich method (Vidas D-Dimer Exclusion; bioMérieux). HAMA, which is known to be responsible for this type of discrepancy, was detected in the patient serum. The false positive result probably impaired with the management of patient. Taking in charge the patient should take into account the possible presence of this antibody. Interference by heterophilic antibodies is not easily detected by the laboratory. Even if their frequency is low, it remains a difficult problem for the biologist. Suspicion generally arises from inconsistency between the clinical data and immunoassay results. A good communication between physician and biologist should avoid to providing false negative or positive results.