English 
Italian Inspiegabili alterazioni di esami coagulativi
Unexpected coagulation test abnormalities
AUTORI
1Dipartimento di Medicina Sperimentale e Clinica, Università di Firenze
2Dipartimento di Biochimica, Università di Firenze
3Azienda Ospedaliera Universitaria Careggi, Firenze
4Istituto Fiorentino di cura e assistenza, Firenze
ABSTRACT
Unexpected coagulation test abnormalities.
A 72 year-old female was screened before a minor orthopaedic surgery with routine coagulation tests, that resulted highly altered. Prothrombin time and activated partial thromboplastin time (PT and aPTT) could not be calculated because the system registered a biphasic curve, protein C and protein S (PC and PS) levels were not measurable and antiphospholipid antibodies were highly positive. Reviewing previous laboratory findings, a serum protein electrophoresis showing the presence of a monoclonal peak in the gamma region was retrieved. A serum immunofixation was then performed, and an IgM kappa monoclonal component was typed; a cryoglobulin test was positive for cryoglobulin type II. To investigate the possible relationship between these laboratory findings, a pool of normal plasma was spiked with the patient IgM monoclonal component at progressively higher concentrations registering a prolongation of PT and aPTT and a slight reduction of PC and PS. The presence of an IgM paraprotein, although not quantitatively relevant, was therefore functionally able to interfere with the coagulation time calculation system. Although coagulation abnormalities in monoclonal gammopathy of undetermined significance are uncommon, these should be attentively investigated, to guarantee a correct laboratory report.