Abstract
Heparin-induced thrombocytopenia (HIT) is caused by the production of autoantibodies against heparin and platelet factor 4 (PF4) complexes, which have platelet-activating properties. Therefore, HIT patients are at high risk of systemic thromboembolism.
Here, we present a patient (87-year-old female) with myeloproliferative neoplasm (MPN) complicated with HIT. Five days after discontinuing a six-day-long prophylactic heparin regimen following hemicolectomy due to colon cancer, the patient exhibited deep vein thrombosis. A therapeutic dose of heparin caused a sudden drop in platelet count and exacerbated systemic venous/arterial thromboembolism on the fourth day of heparin therapy, suggesting complication of HIT. Immediate discontinuation of heparin improved the symptoms and thrombocytopenia. The HIT diagnosis was later confirmed using serological assays as follows: anti-PF4/heparin IgG antibodies were detected using ELISA, and their platelet-activating properties at therapeutic concentrations of heparin were proved by platelet activation assay using washed platelets.
MPN is not always considered a risk factor for HIT. However, HIT in patients with MPN can be a deteriorating factor for unexpected thromboembolism. Hence, HIT should be included in differential diagnosis lists for MPN patients who develop thrombocytopenia and multiple thrombosis after heparin administration, rather than relying on platelet transfusions without further diagnostic procedures.
