[A Case of Heparin-Induced Thrombocytopenia with Discrepancy in the Results of Anti-Platelet Factor 4/Heparin Antibodies between Latex-Particle-Enhanced Immunoturbidimetric Assay and Enzyme Immunoassay].

A female patient in her seventies with diabetes mellitus, hyper-lipidemia and mitral regurgitation was admitted because of the acute heart failure. She was treated with diuretics and vasodilators, however these were not effective. Therefore the CHDF using heparin was required for the patients. After the introduction of CHDF, the platelet count subsequently decreased to less than 7.0 x 10(4)/μl. After stopping CHDF, the platelet count recovered. In the second CHDF treatment, the platelet count decreased again. HIT was suspected because of both the usage of heparin and five points of 4T's score in the patient. Heparin was discontinued immediately and then her platelet count improved. The HIT antibody by latex-particle-enhanced immunoturbidimetric assay was performed simultaneously, however it was not detected. After re-using heparin by heparin lock, platelet count had been decreasing. Furthermore the thrombus was observed in the infusion tube. We considered that a clinical course did not accord with the result of HIT antibody. We measured HIT antibody by another method, an enzyme immunoassay (EIA), and the positive antibody was observed. We encountered a rare case with discrepancy in the results of HIT antibody between two methods. When HIT is suspected by the results from the clinical course and 4T's score, even though the negative HIT antibody, heparin should be discontinued and the different assay for HIT antibody such as an EIA in this case should be performed.