Hit predisposes to thrombosis and, when identified, the condition is then called heparin induced thrombocytopenia and thrombosis hitt. Heparin induced thrombocytopenia hit heparin induced thrombocytopenia hit is a potentially lethal, immunologically induced complication to unfractionated heparin therapy and to a smaller degree, low molecular weight heparin salter, 2016. Understanding the misunderstood disease of heparin induced. Hit is frequently considered in the differential diagnosis of thrombocytopenia occurring in patients on heparin therapy. Mechanism and clinical presentation of heparininduced. Heparininduced thrombocytopenia hit is an adverse reaction to the drug heparin resulting in an abnormally low amount of platelets thrombocytopenia. The american college of chest physicians accp guidelines recommend. Heparininduced thrombocytopenia is a profoundly dangerous. Older terminology distinguishes between two forms of heparin induced thrombocytopenia. Heparin induced thrombocytopenia hit treatment page 1 of 7 disclaimer. A 75yearold female underwent cardiac surgery with intraaortic balloon pump iabp placement.
Heparininduced thrombocytopenia is defined as a decrease in platelet count during or shortly following exposure to heparin 8. Pf4heparin neutralizing protein released by activated platelets type i is non immune mediated not associated with increased risk of thrombosis up to 8% of patients will develop the. Heparininduced thrombocytopenia hit is an antibodymediated adverse drug reac tion that can lead to devastating thromboembolic complications, including pulmonary embolism, ischemic. This algorithm has been developed for md anderson using a multidisciplinary approach considering circumstances particular. Heparininduced thrombocytopenia hit is a serious adverse reaction to heparin. Although thrombocytopenia occurs, bleeding is rare. Heparininduced thrombocytopenia hit occurs in % of patients treated with unfractionated heparin for greater than 5 days. Goodman and gilmans manual of pharmacology and therapeutics. It causes prolonged morbidity, is fatal in 5%10% of cases and causes lifelong disability in another 10% of cases 1. The use of heparin is associated with a risk for hit regardless of the route of administration or dose. Heparininduced thrombocytopenia hit is an immunemediated adverse drug reaction that is caused by heparindependent, plateletactivating igg antibodies that recognize complexes of platelet factor 4. Heparininduced thrombocytopenia hit may develop in two distinct forms, type i and type ii see table 1. Heparininduced thrombocytopenia is a profoundly dangerous, potentially lethal, immunologically mediated adverse drug reaction to unfractionated heparin or, less commonly, to lowmolecular weight heparin.
Key clinical pointsheparin induced thrombocytopenia heparin induced thrombocytopenia hit is characterized by a decrease in the platelet count of more than 50% from the highest platelet count valu. Heparininduced thrombocytopenia differential diagnosis of thrombocytopenia estimating pretest probability of hit 4ts sepsis postresuscitation dilution druginduced including hit hypersplenism. The first, hit type i also called heparin associated thrombocytopenia in the past, is a benign form not associated with an increased risk of thrombosis. Guidelines on the diagnosis and management of heparin. Heparin induced thrombocytopenia hit treatment page 1 of 7. Thrombocytopenia commonly occurs in hospitalized patients, particularly critically ill patients. The following guideline is intended to guide the management of heparin induced thrombocytopenia and includes recommendations for diagnosis and treatment agents. Heparin induced thrombocytopenia adult inpatient clinical. Heparin induced thrombocytopenia hit may develop in two distinct forms, type i and type ii see table 1. Older terminology distinguishes between two forms of heparininduced thrombocytopenia.
Heparin induced thrombocytopenia hit is an antibodymediated adverse drug reac tion that can lead to devastating thromboembolic complications, including pulmonary embolism, ischemic limb necrosis necessitating limb amputation, acute myocardial infarction, and stroke. Heparininduced thrombocytopenia discharge care what you. Laboratory testing reveals a platelet count of 86,000 per cubic millimeter, as compar. Apr 30, 2007 thrombocytopenia commonly occurs in hospitalized patients, particularly critically ill patients. Prospective evaluation of the 4ts score and particle gel immunoassay specific to heparinpf4 for the diagnosis of heparininduced thrombocytopenia see comment.
Heparin induced thrombocytopenia hit ranges from an asymptomatic reaction to heparin with a transient mild thrombocytopenia hit i to a life and limbthreatening immunological reaction, heparin induced thrombocytopenia with thrombosis hitt or hit ii. Clinical picture of heparin induced thrombocytopenia hit and its differentiation from nonhit thrombocytopenia. It causes prolonged morbidity, is fatal in 5%10% of cases and. The diagnostic approach to hit is further enhanced by combining the results of. Heparininduced thrombocytopenia heparininduced thrombocytopenia hit is characterized by a decrease in the platelet count of more than 50% from the highest platelet count value after the start of heparin, an onset 5 to 10 days after the start of heparin, hypercoagulability, and the presence of heparindependent, plateletactivating igg. The heparin induced platelet activation test was carried out using washed platelets of four healthy blood donors. Heparin induced thrombocytopenia hit heparininduced thrombocytopenia hit is a potentially lethal, immunologicallyinduced complication to unfractionated heparin therapy and to a smaller degree, low. Hit usually occurs after you are treated with heparin. Heparin induced thrombocytopenia is defined as a decrease in platelet count during or shortly following exposure to heparin 8. Heparininduced thrombocytopenia blood american society of.
Heparininduced thrombocytopenia hit is a lifethreatening complication of exposure to heparin ie, unfractionated heparin, low molecular weight lmw heparin that occurs in up to 5 percent of patients exposed, regardless of the dose, schedule, or route of administration. Heparin induced thrombocytopenia handout slideshare. Riia on platelets and monocytes to propagate a hypercoagulable state culminating in lifethreatening thrombosis. Treatment and prevention of heparininduced thrombocytopenia. Heparininduced thrombocytopenia hit is an immune complication of heparin therapy caused by antibodies to complexes of platelet factor 4 pf4 and heparin.
Heparininduced thrombocytopenia clinical presentation. Heparininduced thrombocytopenia is a profoundly dangerous, potentially lethal, immunologically mediated adverse drug reaction to unfractionated heparin or, less commonly, to lowmolecular. The 2012 accp clinical guidelines recommend treating hit and hitt with. Heparin induced thrombocytopenia hit is a lifethreatening immune response to heparin and its derivatives that is associated with a high risk of thromboembolic complications. Pdf heparin induced thrombocytopenia hit is a serious and life endangering. Heparininduced thrombocytopenia hit immune complexes heparinpf4igg cause platelet activation via the platelet fc. Heparininduced thrombocytopenia hit is an immune igg mediated condition that occurs secondary to heparin exposure. Has been described without heparin exposure associated with venous and arterial thrombosis typical previous infectious gram neg bacteria or inflammatory event pos immunoassay significant. Heparininduced thrombocytopenia hit is an antibodymediated adverse.
Heparin induced thrombocytopenia hit remains a rare, but significant. Heparininduced thrombocytopenia hit is a lifethreatening complication of exposure to heparin ie, unfractionated heparin, low molecular weight lmw heparin that occurs in up. Heparininduced thrombocytopenia type ii hit is a more serious autoimmune disease causing a low platelet count and paradoxical blood clotting. Heparin induced thrombocytopenia is the development of thrombocytopenia due to the administration of heparin. Hit is usually an immune response which typically occurs 410 days after exposure to heparin. Medical patients and obstetric patients receiving heparin do not need routine. Smock, md associate professor of pathology, medical director, arup hemostasisthrombosis laboratory, university of utah and george m. Heparininduced thrombocytopenia genetic and rare diseases. Hit occurs in up to 5% of patients receiving unfractionated. Heparininduced thrombocytopenia hit is an immunemediated hypercoagulable disorder caused by antibodies to platelet factor 4 pf4 and heparin. Rodgers, md, phd professor of medicine and pathology, medical director, arup hemostasisthrombosis laboratory, university of utah. Heparininduced thrombocytopenia hit is a prothrombotic disorder caused by antibodies that recognize complexes of platelet factor 4 pf4 and heparin. This induces the formation of antipf4 heparin igg antibodies.
Heparininduced thrombocytopenia is a profoundly dangerous, potentially lethal, immunologically mediated adverse drug reaction to unfractionated heparin or, less commonly, to. Heparininduced thrombocytopenia type ii occurs in 15% of patients started on heparin. Negatively charged heparin forms a complex with positively charged platelet factor 4 pf4 1. Riedel r, schmieder a, koster a, kim s, baumgarten g, schewe jc. We present an exemplifying case of severe heparin induced thrombocytopenia hit in an effort to solidify its high priority in the differential diagnosis of thrombocytopenia. Dec 06, 2015 heparin induced thrombocytopenia hit is a prothrombotic disorder caused by antibodies that recognize complexes of platelet factor 4 pf4 and heparin. Platelets aggregate thrombocytopenia and release of thrombogenic microparticles from platelet. Heparin induced thrombocytopenia hit is an immunemediated adverse drug reaction that is caused by heparin dependent, plateletactivating igg antibodies that recognize complexes of platelet factor 4 pf4 bound to heparin. Type i hit, also known as heparin associated thrombocytopenia hat, is a nonimmunologic response to heparin therapy, while type ii hit is an immunologic response to heparin therapy. The heparininduced platelet activation test was carried out using washed platelets of four healthy blood donors. Feb 03, 2020 heparin induced thrombocytopenia hit is a condition that causes a decrease of platelets in the blood. Heparininduced thrombocytopenia hit is a lifethreatening complication of exposure to heparin ie, unfractionated heparin, low molecular weight lmw heparin that occurs in up to 5.
Hit develops in temporal association with heparin therapy and manifests either as an unexplained thrombocytopenia or thrombocytopenia complicated by thrombosis. Key clinical pointsheparininduced thrombocytopenia heparininduced thrombocytopenia hit is characterized by a decrease in the platelet count of more than 50% from the highest platelet count valu. Currently, the term hit is used without a modifier to describe the immunemediated severe form. Heparininduced thrombocytopenia mild to moderate thrombocytopenia or a 50 percent reduction after exposure to heparin or lowmolecularweight heparin arterial and venous thrombosis. Combining heparin with aspirin reduces the risk of thrombosis by. Heparininduced thrombocytopenia hit has three characteristic features that can distinguish it from other causes of thrombocytopenia. Heparininduced thrombocytopenia is a profoundly dangerous, potentially lethal, immunologically mediated adverse drug reaction to unfractionated heparin or, less commonly, to lowmolecular weight. Has been described without heparin exposure associated with venous and arterial thrombosis typical previous infectious gram neg bacteria or inflammatory event pos immunoassay significant inflammatory response causing activation of pf4 without need for heparin, causing platelet activation non heparin polyanions causing activation of pf4. Heparininduced thrombocytopenia type ii hit is a more serious autoimmune disease causing. Heparin induced thrombocytopaenia icm case summaries. One of these is heparininduced thrombocytopenia hit, a common, serious and potentially lifethreatening condition 1,2, and one for which diagnosis can be dif. Heparin induced thrombocytopenia hit is a lifethreatening complication of exposure to heparin ie, unfractionated heparin, low molecular weight lmw heparin that occurs in up to 5 percent of patients exposed, regardless of the dose, schedule, or route of administration.
To assist clinicians with the diagnosis and initial management of heparin. Heparininduced thrombocytopenia hit is a condition that causes a decrease of platelets in the blood. Heparininduced thrombocytopenia hit is a prothrombotic complication mediated by auto antibodies against heparinplatelet complexes. We present an exemplifying case of severe heparininduced thrombocytopenia hit in an. Key words heparin induced thrombocytopenia hit, heparin, danaparoid, lepirudin, argatroban, thrombocytopenia. Overview of heparininduced thrombocytopenia medscape. An iv or central line that is flushed with heparin or coated with heparin.
Heparininduced thrombocytopenia hit is a prothrombotic iatrogenic disorder induced by plateletactivating antibodies that target multimolecular complexes of platelet factor 4 and heparin. Smock, md associate professor of pathology, medical director, arup hemostasisthrombosis laboratory. Heparin induced thrombocytopenia kettering health network. This algorithm has been developed for md anderson using a multidisciplinary approach considering circumstances particular to md andersons specific patient population, services and structure, and clinical information. Guidelines recommend limiting heparin reexposure in patients with a prior. How we manage patients with heparin induced thrombocytopenia. Type i hit, also known as heparinassociated thrombocytopenia hat, is a non. Argatroban and lepirudin are fdaapproved for the treatment of hit. Clinically, see drop in plts by may 03, 2012 heparin induced thrombocytopenia hit is an adverse reaction to the drug heparin resulting in an abnormally low amount of platelets thrombocytopenia. Heparin induced thrombocytopenia differential diagnosis of thrombocytopenia estimating pretest probability of hit 4ts sepsis postresuscitation dilution drug induced including hit hypersplenism platelet consumption or destruction dic massive transfusion primary marrow disorders immune thrombocytopenia itp, ttp antiphospholipid syndrome. Heparininduced thrombocytopenia is the development of thrombocytopenia due to the administration of heparin.
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