REFLUDAN [lepirudin (rDNA) for injection]: the first direct thrombin inhibitor FDA-approved for heparin induced thrombocytopenia (HIT)

Learn more about the benefits of REFLUDAN
This section contains REFLUDAN laboratory and clinical efficacy data
This section contains information regarding the safe administration of REFLUDAN for the treatment of heparin induced thrombocytopenia (HIT)
This section describes the dosage and administration of REFLUDAN in the treatment of heparin induced thrombocytopenia (HIT)
Heparin induced thrombocytopenia
This section describes the clinical use of heparin and its role in the development of heparin induced thrombocytopenia (HIT)
This section describes the clinical consequences of heparin induced thrombocytopenia (HIT)
This section lists the most frequent thromboembolic complications (TECs) that can develop in patients with heparin induced thrombocytopenia (HIT)
This section includes the severe consequences of heparin induced thrombocytopenia (HIT) and underscores the importance of prompt diagnosis and treatment of patients when HIT is suspected
This section lists the average direct medical charges associated with some of the individual thromboembolic complications (TECs) that may occur in patients with heparin induced thrombocytopenia (HIT)
This section describes the signs of heparin induced thrombocytopenia (HIT) and the timeframe in which they generally occur
This section emphasizes the need for platelet count monitoring in all patients receiving heparin to assist in the identification of patients who develop heparin induced thrombocytopenia (HIT)
This section describes the signs, symptoms, and management of heparin induced thrombocytopenia (HIT)
This section describes the laboratory tests that can be used to confirm heparin induced thrombocytopenia (HIT)
A summary of pivotal trial data for REFLUDAN is covered in this section
This section provides access to a variety of resources to obtain in-depth information on heparin induced thrombocytopenia (HIT) and REFLUDAN
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Laboratory confirmation of diagnosis
HIT is predominantly a clinical diagnosis that can be confirmed by laboratory evaluation with functional assays (also known as activation assays), such as the heparin-induced platelet aggregation test (HIPA) or the serotonin release assay (SRA), and/or antigen assays such as the enzyme-linked immunosorbent assay (ELISA). Functional assays detect donor platelet activation in vitro in the presence of therapeutic concentrations of heparin, and antigen assays detect HIT antibodies that recognize heparin-platelet factor 4 complexes. ELISA assays are less specific for clinical HIT than is the SRA, but offer higher sensitivity.3, 9, 15, 16 Because discordant test results occur in 10% to 20% of samples, and neither functional nor antigen assays are 100% reliable for diagnosis, it is recommended that both types of tests be performed.9

Antibody testing, however, should be done only to confirm HIT. Treatment should not be delayed pending laboratory confirmation of HIT.12 In the HAT-2 study, 45% of the HIT patients who developed a TEC did so in the interval between clinical diagnosis and laboratory confirmation (a mean of 1.9 days), further substantiating the need to treat HIT as soon as a clinical diagnosis has been made.3, 17

Heparin-induced thrombocytopenia (HIT): laboratory tests3, 9, 15, 16

 
 Assay 
 		  
 Sensitivity 
 		  
 Specificity  
 		  
 Weaknesses 
 
 
 Functional 
 SRA 
 HIPA 
 		  
 Moderate-High 
 		  
 High 
 		  
 Technically difficult 
 results can 
 differ widely 
 
 
 Washed 
 platelets 
 		  
 Moderate-High 
 		  
 High 
 		  
  
 
 
 Citrated 
 platelet-rich 
 plasma 
 		  
 Moderate 
 		  
 Moderate-High 
 		  
  
 
 
 Antigen/ELISA 
 		  
 High 
 		  
 Poor-Moderate 
 		  
 False positives 
 

The platelet aggregation test, SRA test, and ELISA were evaluated in a recent study.18 The study examined blood samples from 100 patients who were grouped as unlikely, possible, probable, and definite for heparin-induced thrombocytopenia based on clinical criteria. Sensitivity was related to the proportion of patients from the probable or definite groups who tested positive using a given test. Specificity was related to the proportion of patients from the unlikely group who tested positive using a given test.

Heparin-induced thrombocytopenia (HIT)
ELISA/SRA-Clinical utility18

 
  
 		  
 SRA 
 		  
 ELISA 
 
 
   Sensitivity 
 		  
 88% 
 		  
 97% 
 
 
   Specificity 
 		  
 ~100% 
 		  
 86% 
 
 
   (+) Predictive value 
 		  
 ~100% 
 		  
 93% 
 
 
   (-) Predictive value 
 		  
 81% 
 		  
 95% 
 

The study illustrates the benefit of combining results of 2 different diagnostic tests.18

   Both the SRA and ELISA tests have good predictive value; however, the SRA test has good positive predictive value, and the ELISA test has good negative predictive value



Heparin-Induced Thrombocytopenia (HIT)
Heparin Use
Clinical Consequences of HIT
Thromboembolic Complications (TECs)
Iceberg Model of HIT
Economic Consequences of HIT-Associated TECs
When to Suspect HIT Type 2
Vigilant Monitoring is Critical
General Diagnosis and Treatment Algorithm for HIT
Laboratory confirmation of diagnosis

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