Wir berichten über eine 59-jährige Myelom-Patientin, die einen IgA Autoantikörper gegen humanes Thrombin entwickelt hat. Dieser führte in vitro zu verlängerten Gerinnungszeiten und täuschte Hemmkörper gegen sämtliche intrinsische Gerinnungs-Einzelfaktoren vor, wobei die Patientin keine spontane Blutungsneigung aufwies. Der Autoantikörper beeinflusste dabei alle Gerinnungstests, in welchen humanes (nicht aber bovines) Thrombin zum Einsatz kommt. Nachdem das IgA Paraprotein und somit auch der Autoantikörper nach autologer Stammzelltransplantation im Wesentlichen verschwunden war, normalisierten sich auch die Gerinnungsanalysen weitgehend. Zusammenfassend zeigt sich, dass Autoantikörper gegen humanes Thrombin zahlreiche Gerinnungstests in vitro massiv stören können ohne zwangsweise mit einer spontanen Blutungsneigung einhergehen zu müssen. Komplexe oder ungewöhnliche Konstellationen von Gerinnungsanalysen sollten von Anfang an interdisziplinär und in Zusammenarbeit mit einem hochspezialisierten Gerinnungslabor abgeklärt und behandelt werden.

Background We report the case of a 59-year-old multiple myeloma patient in whom an anti-human thrombin IgA antibody led to prolonged in vitro coagulation times, suggesting inhibitors to all intrinsic coagulation factors in the absence of spontaneous bleeding.

Methods Routine and extensive special coagulation tests, in vivo bleeding time, and specific antibody testing were performed.

Results Although the patient did not suffer from spontaneous bleeding and had a normal in vivo bleeding time, the anti-human thrombin IgA autoantibody affected all coagulation assays involving human thrombin in vitro, mimicking inhibitors to intrinsic coagulation factors. As the IgA paraprotein and the IgA antibody virtually disappeared after autologous stem cell transplantation, the coagulation tests also largely normalized.

Conclusion Antibodies to human thrombin may interfere with all coagulation assays involving thrombin, imitating a severe coagulopathy. However, in vivo they do not necessarily lead to strongly increased bleeding tendency. Complex and ambiguous coagulation abnormalities should be evaluated and treated in an interdisciplinary setting, including a highly specialized coagulation laboratory, from the beginning.

C.I., L.L., and A.G. requested, performed and/or interpreted coagulation tests. J.A. performed and interpreted autoantibody studies. C.F., C.A.Ü. and C.I. got clinical data. C.I. and J.A. wrote the original draft. All authors read, revised, and approved the submitted version of the manuscript.

If case reports with less than five patients are fully anonymized, they do not require approval by the Ethics Commission at the Medical University of Innsbruck.

At the time of writing this manuscript, unfortunately the patient was already deceased.

All relevant data are contained within the manuscript.

Received: 16 August 2023

Accepted: 13 November 2023

Article published online:
01 March 2024

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