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. Hit predisposes to thrombosis and, when identified, the condition is then called heparin induced thrombocytopenia and thrombosis hitt. To assist clinicians with the diagnosis and initial management of heparin. 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. Negatively charged heparin forms a complex with positively charged platelet factor 4 pf4 1. This induces the formation of antipf4 heparin igg antibodies. Heparininduced thrombocytopenia hit is a prothrombotic iatrogenic disorder induced by plateletactivating antibodies that target multimolecular complexes of platelet factor 4 and heparin.
Heparininduced thrombocytopenia type ii hit is a more serious autoimmune disease causing. Heparin induced thrombocytopenia hit remains a rare, but significant. Treatment and prevention of heparininduced thrombocytopenia. Older terminology distinguishes between two forms of heparininduced thrombocytopenia.
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. Hit develops in temporal association with heparin therapy and manifests either as an unexplained thrombocytopenia or thrombocytopenia complicated by thrombosis. Heparin induced thrombocytopenia is the development of thrombocytopenia due to the administration of heparin. Medical patients and obstetric patients receiving heparin do not need routine. Heparin induced thrombocytopenia mild to moderate thrombocytopenia or a 50 percent reduction after exposure to heparin or lowmolecularweight heparin arterial and venous thrombosis. 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. 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. Overview of heparininduced thrombocytopenia medscape. Type i hit, also known as heparinassociated thrombocytopenia hat, is a non. Hit usually occurs after you are treated with heparin. Hit is usually an immune response which typically occurs 410 days after exposure to heparin. The following guideline is intended to guide the management of heparin induced thrombocytopenia and includes recommendations for diagnosis and treatment agents.
Heparininduced thrombocytopenia hit is a lifethreatening immune response to heparin and its derivatives that is associated with a high risk of thromboembolic complications. This algorithm has been developed for md anderson using a multidisciplinary approach considering circumstances particular. Riedel r, schmieder a, koster a, kim s, baumgarten g, schewe jc. Pdf heparin induced thrombocytopenia hit is a serious and life endangering. Heparininduced thrombocytopenia hit has three characteristic features that can distinguish it from other causes of thrombocytopenia. Heparininduced thrombocytopenia hit is a prothrombotic disorder caused by antibodies that recognize complexes of platelet factor 4 pf4 and heparin. Heparininduced thrombocytopenia is defined as a decrease in platelet count during or shortly following exposure to heparin 8. Thrombocytopenia commonly occurs in hospitalized patients, particularly critically ill patients. Heparininduced thrombocytopenia is the development of thrombocytopenia due to the administration of heparin. Heparininduced thrombocytopenia is a profoundly dangerous. Dec 06, 2015 heparin induced thrombocytopenia hit is a prothrombotic disorder caused by antibodies that recognize complexes of platelet factor 4 pf4 and heparin. A 75yearold female underwent cardiac surgery with intraaortic balloon pump iabp placement. Smock, md associate professor of pathology, medical director, arup hemostasisthrombosis laboratory. Heparin induced thrombocytopenia is defined as a decrease in platelet count during or shortly following exposure to heparin 8.
Heparininduced thrombocytopenia hit is an immune complication of heparin. Guidelines on the diagnosis and management of heparin. 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. The american college of chest physicians accp guidelines recommend. Heparininduced thrombocytopenia hit is an adverse reaction to the drug heparin resulting in an abnormally low amount of platelets thrombocytopenia. It causes prolonged morbidity, is fatal in 5%10% of cases and causes lifelong disability in another 10% of cases 1. Heparininduced thrombocytopenia is a profoundly dangerous, potentially lethal, immunologically mediated adverse drug reaction to unfractionated heparin or, less commonly, to.
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 hit is a lifethreatening immune response to heparin and its derivatives that is associated with a high risk of thromboembolic complications. Rates of mortality and morbidity have decreased from 20% to 610% with improvements in early. Heparininduced thrombocytopenia blood american society of.
Heparininduced thrombocytopenia clinical presentation. Heparininduced thrombocytopenia mild to moderate thrombocytopenia or a 50 percent reduction after exposure to heparin or lowmolecularweight heparin arterial and venous thrombosis. Laboratory testing reveals a platelet count of 86,000 per cubic millimeter, as compar. Heparininduced thrombocytopenia type ii occurs in 15% of patients started on heparin. Mechanism and clinical presentation of heparininduced. Older terminology distinguishes between two forms of heparin induced thrombocytopenia. Apr 30, 2007 thrombocytopenia commonly occurs in hospitalized patients, particularly critically ill patients.
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. Understanding the misunderstood disease of heparin induced. Heparininduced thrombocytopenia type ii hit is a more serious autoimmune disease causing a low platelet count and paradoxical blood clotting. 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. Heparin induced thrombocytopenia hit treatment page 1 of 7. Heparininduced thrombocytopenia is a profoundly dangerous, potentially lethal, immunologically mediated adverse drug reaction to unfractionated heparin or, less commonly, to lowmolecular weight heparin. Target population adult patients with suspicion or diagnosis of heparin induced thrombocytopenia key practice recommendations screening for hit 1. Clinical picture of heparin induced thrombocytopenia hit and its differentiation from nonhit thrombocytopenia. Pathogenic antibodies to pf4 heparin bind and activate cellular fc. Goodman and gilmans manual of pharmacology and therapeutics. Heparininduced thrombocytopenia hit is an immune igg mediated condition that occurs secondary to heparin exposure. Heparininduced thrombocytopenia hit is a condition that causes a decrease of platelets in the blood.
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. It causes prolonged morbidity, is fatal in 5%10% of cases and. Heparininduced thrombocytopenia hit is a prothrombotic complication mediated by auto antibodies against heparinplatelet complexes. Heparin induced thrombocytopenia hit heparininduced thrombocytopenia hit is a potentially lethal, immunologicallyinduced complication to unfractionated heparin therapy and to a smaller degree, low. Prospective evaluation of the 4ts score and particle gel immunoassay specific to heparinpf4 for the diagnosis of heparininduced thrombocytopenia see comment. Heparininduced thrombocytopenia hit is an antibodymediated adverse. Heparininduced thrombocytopenia hit is an antibodymediated adverse drug reac tion that can lead to devastating thromboembolic complications, including pulmonary embolism, ischemic. Heparininduced thrombocytopenia hit immune complexes heparinpf4igg cause platelet activation via the platelet fc. A 63yearold man with coronary artery disease who has recently undergone bypass surgery presents with dyspnea. 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.
Hit is frequently considered in the differential diagnosis of thrombocytopenia occurring in patients on heparin therapy. The 2012 accp clinical guidelines recommend treating hit and hitt with. Although thrombocytopenia occurs, bleeding is rare. The heparininduced platelet activation test was carried out using washed platelets of four healthy blood donors. Heparin induced thrombocytopenia hit treatment page 1 of 7 disclaimer. Heparin induced thrombocytopenia hit may develop in two distinct forms, type i and type ii see table 1. 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. The use of heparin is associated with a risk for hit regardless of the route of administration or dose. Heparininduced thrombocytopenia type i is harmless, causing a mild and transient reduction in platelet count. Heparin induced thrombocytopenia adult inpatient clinical. Heparin induced thrombocytopaenia icm case summaries. Smock, md associate professor of pathology, medical director, arup hemostasisthrombosis laboratory, university of utah and george m. One of these is heparininduced thrombocytopenia hit, a common, serious and potentially lifethreatening condition 1,2, and one for which diagnosis can be dif.
The diagnostic approach to hit is further enhanced by combining the results of. Heparin induced thrombocytopenia kettering health network. 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. Combining heparin with aspirin reduces the risk of thrombosis by. Heparininduced thrombocytopenia is a profoundly dangerous, potentially lethal, immunologically mediated adverse drug reaction to unfractionated heparin or, less commonly, to lowmolecular. Heparininduced thrombocytopenia hit may develop in two distinct forms, type i and type ii see table 1. Currently, the term hit is used without a modifier to describe the immunemediated severe form.
We present an exemplifying case of severe heparininduced thrombocytopenia hit in an. The heparin induced platelet activation test was carried out using washed platelets of four healthy blood donors. Heparininduced thrombocytopenia hit is a serious adverse reaction to heparin. Rodgers, md, phd professor of medicine and pathology, medical director, arup hemostasisthrombosis laboratory, university of utah. Heparininduced thrombocytopenia hit occurs in % of patients treated with unfractionated heparin for greater than 5 days. Hit occurs in up to 5% of patients receiving unfractionated. 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. Heparininduced thrombocytopenia hit is an immunemediated adverse drug reaction that is caused by heparindependent, plateletactivating igg antibodies that recognize complexes of platelet factor 4. 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. Has been described without heparin exposure associated with venous and arterial thrombosis typical previous infectious gram neg bacteria or inflammatory event pos immunoassay significant. Feb 03, 2020 heparin induced thrombocytopenia hit is a condition that causes a decrease of platelets in the blood. How we manage patients with heparin induced 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. Riia on platelets and monocytes to propagate a hypercoagulable state culminating in lifethreatening thrombosis.
Heparininduced thrombocytopenia what you need to know. Heparininduced thrombocytopenia discharge care what you. Heparininduced thrombocytopenia hit is an immune complication of heparin therapy caused by antibodies to complexes of platelet factor 4 pf4 and heparin. Heparininduced thrombocytopenia is a profoundly dangerous, potentially lethal, immunologically mediated adverse drug reaction to unfractionated heparin or, less commonly, to lowmolecular weight. Heparininduced thrombocytopenia hit is an immunemediated hypercoagulable disorder caused by antibodies to platelet factor 4 pf4 and heparin. 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. Heparin induced thrombocytopenia handout slideshare. Key words heparin induced thrombocytopenia hit, heparin, danaparoid, lepirudin, argatroban, thrombocytopenia. Argatroban and lepirudin are fdaapproved for the treatment of hit.
Heparininduced thrombocytopenia differential diagnosis of thrombocytopenia estimating pretest probability of hit 4ts sepsis postresuscitation dilution druginduced including hit hypersplenism. 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. Platelets aggregate thrombocytopenia and release of thrombogenic microparticles from platelet. An iv or central line that is flushed with heparin or coated with heparin. Guidelines recommend limiting heparin reexposure in patients with a prior. Heparininduced thrombocytopenia hit is a lifethreatening complication of exposure to heparin ie, unfractionated heparin, low molecular weight lmw heparin that occurs in up. Riia thrombocytopenia high risk of thrombosis occurs in 50% of untreated cases may be venous dvt, pe or arterial limb ischemia, stroke, mi thrombotic complications can be fatal.
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