Biochemia Medica, Vol. 27 No. 3, 2017.
Other
https://doi.org/10.11613/BM.2017.030801
False positive immunoassay for heparin-induced thrombocytopenia in the presence of monoclonal gammopathy: a case report
Ivana Markovic
Zeljko Debeljak
Bojana Bosnjak
Maja Marijanovic
Abstract
Heparin induced thrombocytopenia (HIT) is a life-threatening disorder which diagnosis depends on laboratory evaluation. The objective of this report
is to present the impact of different laboratory methods for HIT detection on the diagnostic evaluation process. In this case, a 78-year old female
patient previously diagnosed with monoclonal gammopathy of undetermined significance (MGUS) was administered with heparin for pulmonary
embolism treatment. Patient’s initial diagnostic work-up (determination of platelet count and prothrombin time measurement for monitoring of
pharmacotherapy) was followed by the clinical estimation of HIT likelihood by “4Ts” score, two immunoassays (ID-PaGIA Heparin/PF4 Antibody Test
and ELISA PF4 IgG assay) and one functional test called high-performance liquid chromatography serotonin release assay (HPLC-SRA). The result of
“4Ts” score indicated a low likelihood of HIT but persistent thrombocytopenia that appeared days after discontinuation of heparin therapy suggested
delayed-onset HIT. Both immunoassays were positive for presence of HIT-autoantibodies, while the functional HPLC-SRA was negative. Since different
methods gave opposing results, their interpretation required great attention. In comparison to the HPLC-SRA, immunoassays are prone to the
analytical interferences associated with the presence of non-specific antibodies, which may lead to false positive results. In this case, where the patient
is known to produce antibodies of undetermined significance, HIT was ruled out as the possible cause of persistent thrombocytopenia primarily
due to the negative result of HPLC-SRA, which is not prone to this type of interferences, but also due to the low “4Ts” clinical score.
Keywords
heparin-induced thrombocytopenia; immunoassay; functional serotonin release assay; cross-reaction; monoclonal gammopathy of undetermined significance
Hrčak ID:
187594
URI
Publication date:
15.10.2017.
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