Low Molecular Weight Heparin Fractions as an Alternative Therapy in Heparin-induced Thrombocytopenia

Abstract

Eight patients with a delayed-onset heparin-induced thrombocytopenia, with thrombotic complications requiring immediate anticoagulation in 7 of them, were given low molecular weight heparin (LMWH) fractions as alternative therapy. This treatment led to normalization of platelet count within 3–5 days in 6 patients with clinical recovery in 5. In 2 patients, thrombocytopenia persisted despite LMWH therapy. In vitro platelet aggregation tests performed in all patients gave evidence of a relationship between the presence (or absence) of a LMWH-dependent platelet-aggregating factor in the patients’ plasma and the persistence (or correction) of the thrombocytopenia with LMWH therapy. Although positive in vitro tests may not necessarily be associated with thrombocytopenia, in vitro testing may prove to be a useful guide before giving LMWH fractions as an alternative therapy in patients with heparin-induced thrombocytopenia requiring immediate anticoagulation.

Orgaran in Heparin-lnduced Thrombocytopenia

“…Recently, the results of sev eral retrospective studies have indicated that patients with HIT are at risk of adverse clini cal outcomes such as persistent thrombocyto penia, limb amputation and death, if they are treated with LMW heparins which cross-react with their antibodies in vitro [6,7], However, this finding has yet to be confirmed by pro spective, controlled, randomised studies.…”

Antigen Generation in Heparin-Associated Thrombocytopenia: The Nonimmunologic Type and the Immunologic Type Are Closely Linked in Their Pathogenesis

“…Based on these data, HAT type II should be expected in 0.5 to 2% of patients receiving therapeutical amounts of heparin for more than 5 days. Certainly also, low-dose heparin for prophylaxis can cause HAT type II 59,74,77,[89][90][91] As in the majority of patients diagnosed in our laboratory, Laster et al 92 found HAT type II was caused in 82% of their 169 HAT patients by low-dose heparin treatment. A few case reports document HAT type II caused by minimal amounts of heparin flushes or heparin-coated intra-arterial lines.…”

Successful Administration of Low Molecular Weight Heparin in a Patient with Heparin-lnduced Thrombocytopenia and Coumarin-lnduced Skin Necrosis

“…The size of the heparin molecule influences its interactions with platelets and they arc reduced with heparin molecules un der 5,000 D, especially when the preparation is rich in molecules with strong affinity to antithrombin III. A possible explanation is that LMWHs, because of their relatively small size, compared to UH can bind either anti thrombin III or platelets [14], Therefore, LMWHs can be successfully used as an anti coagulant in a state of HIT [ 15]. Although rare cases of LMWH-induced thrombocytopenia have been reported [16], changing standard heparin to LMWH normalizes the platelet count in most cases of HIT [17], The experi ence with LMWH in thrombocytopenia ex cept in patients with HIT is limited.…”