APC resistance as an additional thrombotic risk factor in a patient suffering from polycythemia vera and recurrent thrombosis

Abstract

Patients with polycythemia vera (PV) have a high risk of thrombosis. However, thrombosis is not sufficiently predictable with standard diagnostic procedures. We report on a patient with PV and recurrent thrombosis who nevertheless had a low platelet count while under therapy with hydroxyurea. As a result of duodenal ulcer and gastrointestinal bleeding, treatment with phenprocoumon was stopped years ago. Recently, heterozygosity for the factor V gene defect was diagnosed and anticoagulation therapy was reconsidered. In conclusion, the presence of resistance to activated protein C was an additional thrombotic risk factor that was important for our decision to change the treatment strategy in our patient.

The Optimal Management of Polycythaemia Vera

“…The use of anagrelide (Anagrelide Study Group, 1992) to reduce the platelet count in the absence of symptoms is also unjustified as there is no evidence that an elevated platelet count per se is harmful (Wehmeier et al , 1991; Ruggeri et al , 1998) except, perhaps, to the extent that it distracts from the more important issue, the red cell mass, or the possibility that another unrelated cause for thrombosis such as the antiphospholipid syndrome (Harrison & MacHin, 1997; Randi et al , 1999) or other risk factors (Watson & Key, 1993; Lamparter et al , 1997) are present. Aspirin or ibuprofen are appropriate for the treatment of erythromelalgia (Kurzrock & Cohen, 1989) and its' central nervous system equivalent (Michiels, 1997), unless the platelet count is so high that there is a risk of haemorrhage owing to a decrease in high‐molecular‐weight von Willebrand multimers and low ristocetin cofactor activity (Budde et al , 1993; van Genderen et al , 1996).…”

Polycythemia vera: myths, mechanisms, and management

“…287 Finally, there is no evidence that other coagulation defects predisposing to hypercoagulability are more prevalent in polycythemia vera patients than in the general population, although they are certainly not immune to them. 288,289 Phlebotomy therapy: pros and cons Not only is there compelling evidence that increased blood viscosity due to an elevated red cell mass is the principal basis for the hypercoagulable state in polycythemia vera, there is equally strong evidence that phlebotomy, a venerable practice that was well known in the Hippocratic era, is the most effective remedy. Unfortunately, it is both an irony and a tragedy that this is one Hippocratic principle that many hematologists have been reluctant to embrace wholeheartedly.…”

Hyperviscosity in Polycythemia Vera and Other Red Cell Abnormalities

“…Interference with the action of nitrous oxide 11 Leukocyte activation 12 Impairment of fibrinolysis 13 Increased activated protein C resistance 14 Increased markers of clotting (TAT complex, prothrombin…”

“…These factors are listed in Table 2. [8][9][10][11][12][13][14][15] They include increased hematocrit, thrombocytosis, impaired fibrinolytic activity, 13,16 platelet activation, leukocyte activation, endothelial damage, interactions between platelets and endothelium, different modalities of therapy, and increased whole-blood viscosity. Among these factors, the increase in blood viscosity, and hence the impairment of blood flow, is unquestionably the major factor.…”