In 170 patients, platelet counts began to fall 4 or more days after heparin therapy was started most commonly between days 4 and 10 typicalonset thrombocytopenia. Hit ii which is an autoimmunemediated adverse effect of heparin. These canadian researchers describe the time course of serologically confirmed heparininduced thrombocytopenia. It is considered the most severe nonbleeding adverse reaction of heparin. Jun 05, 2014 the existence of spontaneous heparin induced thrombocytopenia hit syndrome or autoimmune hit, defined as a transient prothrombotic thrombocytopenic disorder without proximate heparin exposure serologically indistinguishable from hit, is controversial. Heparininduced hyperkalemia jama internal medicine jama. Heparininduced thrombocytopenia hit is a lifethreatening immune response to heparin and its derivatives that is associated with a high risk of thromboembolic complications. Heparininduced thrombocytopenia hit is an immune complication of heparin therapy caused by antibodies to complexes of platelet factor 4 pf4 and heparin. Diagnosis of hit is based on both clinical thrombocytopenia. Because the platelet count normalizes even with continued heparin. Heparininduced thrombocytopenia new england journal.
Learn heparin induced thrombocytopenia hit anticoagulants pharmacology for medicine faster and easier with picmonics unforgettable images and stories. Heparin sodium is routinely used in the prophylaxis against deep venous thrombosis in medical and surgical patients. Heparininduced thrombocytopenia and the new oral anticoagulants juan m. Hit is essentially a prothrombotic disorder mediated by an igg antiplatelet factor 4 heparin.
Heparininduced thrombocytopenia retrospective analysis of. Hit occurs in up to 5% of patients receiving unfractionated heparin. The rates of hit vary significantly based on the clinical context, but estimates have ranged from 0. The new england journal of medicine 812 n engl j med 355. Approach to thrombocytopenia conditions that need to be considered. Onset of hit usually occurs 514 days after the start of heparin.
Hit usually occurs after you are treated with heparin. The following guideline is intended to guide the management of heparin induced thrombocytopenia and includes recommendations for diagnosis and treatment agents. Feb 03, 2020 heparin induced thrombocytopenia hit is a condition that causes a decrease of platelets in the blood. Pathogenic antibodies to pf4heparin bind and activate cellular fc. Heparininduced thrombocytopenia genetic and rare diseases. Heparin induced thrombocytopenia associated with fondaparinux. Drug induced thrombocytopenia dit is a relatively common clinical disorder. Laboratory testing reveals a platelet count of 86,000 per cubic millimeter, as compar. Riia on the platelet surface, platelets become activated, microparticles are released, and the coagulation cascade is triggered. Heparininduced thrombocytopenia hit is an immunemediated hypercoagulable disorder caused by antibodies to platelet factor 4 pf4 and heparin. Hit develops in temporal association with heparin therapy and manifests either as an unexplained thrombocytopenia or thrombocytopenia complicated by thrombosis. Heparin induced thrombocytopenia hit is a lifethreatening complication of exposure to heparin eg, unfractionated heparin, low molecular weight lmw heparin that occurs in a small percentage of patients exposed, regardless of the dose, schedule, or route of administration.
An iv or central line that is flushed with heparin or coated with heparin. Heparin induced thrombocytopenia thrombotic thrombocytopenic purpura atypical hemolytic uremic syndrome immune thrombocytopenic purpura thrombocytopenia causes. It is imperative to provide rapid identification and removal of the offending agent before clinically significant bleeding or, in the case of heparin, thrombosis occurs. Heparin induced thrombocytopenia hit is by far the most relevant pathological association of it encountered by clinicians. Riia on platelets and monocytes to propagate a hypercoagulable state culminating in lifethreatening thrombosis.
We studied the temporal relation between previous or current heparin therapy and the onset of hep. Antithrombotic therapy is required to manage heparin induced thrombocytopenia hitbut currently approved agents such as argatroban must be given parenterally and closely monitored. A 75yearold female underwent cardiac surgery with intraaortic balloon pump iabp placement. Heparin induced thrombocytopenia hit treatment page 1 of 7 disclaimer. May 04, 2001 these canadian researchers describe the time course of serologically confirmed heparin induced thrombocytopenia in 243 patients. Heparin induced thrombocytopenia thrombocytopenia heparin exclusion of other causes of thrombocytopenia with or without. Heparininduced thrombocytopenia hit is known for its strong association with thrombosis and distinct pathogenesis involving. Correspondence from the new england journal of medicine coagulopathy and antiphospholipid antibodies in patients with covid19. May 03, 2012 heparin induced thrombocytopenia hit is an adverse reaction to the drug heparin resulting in an abnormally low amount of platelets thrombocytopenia. Nonheparin anticoagulants for heparininduced thrombocytopenia. Heparininduced thrombocytopenia hit is considered the most common form of drug induced thrombocytopenia as well as one of the common causes of thrombocytopenia in hospitalized patients. While the treatment of hitt hit with thrombosis with anticoagulation is well established, the risks and treatment of isolated hit are unclear. Hit develops in temporal association with heparin therapy and manifests either as an unexplained thrombocytopenia or thrombocytopenia. N engl j med dec at 23 years of followup, life expectancy was nearly 3 years longer with prostatectomy than with watchful waiting.
Aug 10, 2010 isolated heparin induced thrombocytopenia is defined as a fall in platelet count associated with a positive heparin pf4 antibody test, in the absence of clinically overt thrombosis. Heparininduced thrombocytopenia is caused by antibodies against complexes of platelet factor 4. Heparin induced thrombocytopenia hit treatment page 1 of 7. A 63yearold man with coronary artery disease who has recently undergone bypass surgery presents with dyspnea. Heparininduced thrombocytopenia is the most important of the immunemediated, druginduced thrombocytopenias. Heparininduced thrombocytopenia blood american society. Thrombocytopenia following heparin administration can be associated with an immune reaction, now referred to as heparininduced thrombocytopenia.
Hit can be associated with thrombosis formation in the more serious forms. Coagulopathy and antiphospholipid antibodies in patients. Spontaneous heparininduced thrombocytopenia syndrome. Hit is associated with 50fold increase in thrombosis risk. Hospital acquired thrombocytopenia drug induced acute illness related. Heparin induced thrombocytopenia is a prothrombotic disorder mediated by igg antibodies. Some heparin recipients develop thrombocytopenia, which is caused by igg antibodies against complexes of platelet factor 4 and heparin. Recent data show that up to 8% of heparinized patients will develop the antibody associated with hit and that approximately 15% of patients on heparin will progress to develop hit with thrombocytopenia 11, 12, suffering from venous andor arterial thrombosis in at least one. The new england journal of medicine downloaded from nejm. Recent data show that up to 8% of heparinized patients will develop the antibody associated with hit and that approximately 15% of patients on heparin will progress to develop hit with thrombocytopenia. Consequently, heparin induced thrombocytopenia hit, an immune complication of heparin therapy, remains a highly relevant complication for the hematology practitioner to diagnose and manage. Highdose intravenous immunoglobulin for the treatment. Heparininduced thrombocytopenia hit is a prothrombotic, immunemediated adverse reaction that occurs after exposure to unfractionated heparin ufh, low molecular weight heparin. The following guideline is intended to guide the diagnosis and management of heparin induced thrombocytopenia.
This algorithm has been developed for md anderson using a multidisciplinary approach considering circumstances particular. Heparin induced thrombocytopenia hit is a clinically important drug induced complication. The adverse drug effect known as heparininduced thrombocytopenia hit shows many similarities to a bacterial. Disclosure forms provided by the authors are available with the full text of this case at nejm. Platelet factor 4 pf4 molecules bind to heparin on the surface of platelets to form a neoantigen that is recognised by hit igg antibodies. Shuyang zhang and yongzhe li contributed equally to this case. Jan 04, 2020 n engl j med dec at 23 years of followup, life expectancy was nearly 3 years longer with prostatectomy than with watchful waiting. Understanding the misunderstood disease of heparin induced. Picmonic is research proven to increase your memory retention and test scores. Risk for heparin induced thrombocytopenia with unfractionated and lowmolecularweight heparin thromboprophylaxis. Delayedonset heparininduced thrombocytopenia and cerebral. 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. 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.
Heparininduced thrombocytopenia in acute coronary syndrome. Hit results from an interaction between negatively charged heparin. However, there have been three reported isolated cases of fondaparinux. Mar 30, 2020 heparin induced thrombocytopenia nejm pdf antiplatelet factor 4heparin antibodies present a major risk of heparininduced thrombocytopenia hit. Heparin induced thrombocytopenia hit anticoagulants. Fondaparinux is safe for heparininduced thrombocytopenia. Heparininduced thrombocytopenia hit is an adverse reaction to the drug heparin resulting in an abnormally low amount of platelets thrombocytopenia. Heparininduced thrombocytopenia clinical presentation. Heparininduced thrombocytopenia aetiology bmj best practice. Smock, md associate professor of pathology, medical director, arup hemostasisthrombosis laboratory. Heparininduced thrombocytopenia hit is a potentially lifethreatening immune complication which occurs after exposure to unfractionated heparin ufh or less commonly, to lowmolecular weight heparins lmwhs.
Heparininduced thrombocytopenia what you need to know. Hit is characterized by a platelet count fall of more than 50% at 5 to 10 days after the start of heparin and hypercoagulability. 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. Heparininduced thrombocytopenia and optimal management of. Currently, the term hit is used without a modifier to describe the immunemediated severe form. Heparininduced thrombocytopenia is the most important of the immunemediated, drug induced thrombocytopenias. Correspondence from the new england journal of medicine heparin induced thrombocytopenia. Antithrombotic therapy is required to manage heparin induced thrombocytopenia. In contrast to other drug induced immune thrombocytopenia syndromes, hit is generally not associated with bleeding.
Heparin induced thrombocytopenia hit is a complication of heparin therapy and is characterized by two types. Heparin induced thrombocytopenia hit is a lifethreatening immune response to heparin and its derivatives that is associated with a high risk of thromboembolic complications. May 04, 2015 heparin induced thrombocytopenia hit, often with thrombosis, is suspected when the platelet count declines in a patient receiving heparin. Mar 08, 2012 heparin induced thrombocytopenia hit, formerly hit type ii, is a prothrombotic and potentially lethal disorder caused by platelet, endothelial, and monocyteactivating antibodies that target multimolecular complexes of platelet factor 4 pf4 and heparin. A synopsis of the clinical uses of argatroban springerlink. To assist clinicians with the diagnosis and initial management of heparin. Heparin induced thrombocytopenia hit is an immunemediated hypercoagulable disorder caused by antibodies to platelet factor 4 pf4 and heparin. Apr 30, 2007 thrombocytopenia commonly occurs in hospitalized patients, particularly critically ill patients. Delayedonset heparininduced thrombocytopenia, a newly described syndrome of immunemediated thrombocytopenia that.
Heparin induced thrombocytopenia mild to moderate thrombocytopenia or a 50 percent reduction after exposure to heparin or lowmolecularweight heparin arterial and venous thrombosis. Hit is a dangerous, potentially lethal, immunologicallymediated adverse drug reaction to unfractionated heparin ufh or, less commonly, low molecular weight heparin lmwh. Correspondence from the new england journal of medicine heparin induced thrombocytopenia nejm. Heparin induced thrombocytopenia associated with fondaparinux beng h.
The propensity for thrombosis distinguishes hit from other common drug induced. A new clinical practice article provides an overview of heparin induced thrombocytopenia. Pf4 antibodies and thus has a very low likelihood of causing, or exacerbating, hit. Key clinical pointsheparin induced thrombocytopenia heparininduced thrombocytopenia hit is characterized by a decrease in the platelet count of more than 50% from the highest platelet count valu. Target population adult patients with suspicion or diagnosis of heparin induced thrombocytopenia. Hit is a transient, immunemediated adverse drug reaction in patients recently exposed to heparin that generally produces thrombocytopenia and often results in venous andor arterial thrombosis. Guidance for the practical management of the heparin. Heparininduced thrombocytopenia is a profoundly dangerous, potentially lethal, immunologically mediated adverse drug reaction to unfractionated heparin or, less commonly, to lowmolecular weight heparin. Heparin induced anaphylactoid reaction associated with heparin induced thrombocytopenia in the ed. Platelet factor 4 complexed to heparin is the target for antibodies generated in heparin induced thrombocytopenia. Temporal aspects of heparininduced thrombocytopenia nejm.
It is an immunemediated phenomenon caused by antibodies directed against complexes of heparin. Heparin induced thrombocytopenia nejm pdf antiplatelet factor 4 heparin antibodies present a major risk of heparin induced thrombocytopenia hit. Target population adult patients with suspicion or diagnosis of heparin induced thrombocytopenia key practice recommendations screening for hit 1. Pdf heparin is widely used for the prevention and treatment of thrombotic and particularly cardiovascular disorders. This article concludes with a concise table of clinical management questions and guidance recommendations to provide a quick reference for the practical management of heparin, low molecular weight heparin and fondaparinux. Patients with heparininduced thrombocytopenia hit require. Heparin induced thrombocytopenia adult inpatient clinical. The pocket guides are available as a mobile application for ios and android devices, as a mobilefriendly website, and as pdf downloads. Heparininduced thrombocytopenia hit, formerly hit type ii, is a prothrombotic and potentially lethal disorder caused by platelet, endothelial, and monocyteactivating antibodies that target multimolecular complexes of platelet factor 4 pf4 and heparin. Heparininduced thrombocytopenia is a prothrombotic disorder mediated by igg antibodies. Clinical features that help distinguish hit from other forms of thrombocytopenia include the timing of onset and the presence of thrombosis eg, venous thromboembolism or other sequelae. Heparin induced thrombocytopenia hit is an unusual immunemediated adverse drug reaction with the central paradox being its strong association with thrombosis, despite the role of an anticoagulant heparin in causing a fall in platelet count thrombocytopenia.
Hit is usually an immune response which typically occurs 410 days after exposure to heparin. Evidence from two studies clark np jama im 2015 and birnie dh nejm. Older terminology distinguishes between two forms of heparin induced thrombocytopenia. 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, fifthedition although first reported in 1973, immune heparininduced thrombocytopenia hit remains one of the most frequent and devastating adverse drug reactions encountered by physicians. Background heparin induced thrombocytopenia is a relatively common antibodymediated drug reaction. Antibodies from patients with heparin induced thrombocytopenia thrombosis are specific for platelet factor 4 complexed with heparin or bound to endothelial cells. While most physicians are aware of heparininduced thrombocytopenia and skin necrosis, the association of heparin and hyperkalemia is less well recognized. Introduction heparin induced thrombocytopenia hit is a common cause of thrombocytopenia. Recent advances in the diagnosis and treatment of heparin. Heparin induced thrombocytopenia hit, even rare, is a lifethreatening, immunemediated complication of heparin exposure. Successful management depends on quickly discontinuing all sources of heparin and initiating alternative anticoagulants.
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