Heparin-induced thrombocytopenia risk factors

Heparin-induced thrombocytopenia
Home
Patient Information
Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Heparin-induced thrombocytopenia from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
Diagnostic Criteria
History and Symptoms
Physical Examination
Laboratory Findings
Electrocardiogram
Chest X Ray
Echocardiography and Ultrasound
CT
MRI
Other Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Primary Prevention
Secondary Prevention
Cost-Effectiveness of Therapy
Future or Investigational Therapies
Case Studies
Case #1
Heparin-induced thrombocytopenia risk factors On the Web
Most recent articles
Most cited articles
Review articles
CME Programs
Powerpoint slides
Images
American Roentgen Ray Society Images of Heparin-induced thrombocytopenia risk factors All Images X-rays Echo & Ultrasound CT Images MRI
Ongoing Trials at Clinical Trials.gov
US National Guidelines Clearinghouse
NICE Guidance
FDA on Heparin-induced thrombocytopenia risk factors
CDC on Heparin-induced thrombocytopenia risk factors
Heparin-induced thrombocytopenia risk factors in the news
Blogs on Heparin-induced thrombocytopenia risk factors
Directions to Hospitals Treating Heparin-induced thrombocytopenia
Risk calculators and risk factors for Heparin-induced thrombocytopenia risk factors

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2], Aric C. Hall, M.D., [3]

Overview

Heparin-induced thrombocytopenia is diagnosed when the platelet count falls by > 50% typically after 5-10 days of heparin therapy. Genetic risk factors for thrombosis such as factor V Leiden, prothrombin gene mutation, methylenetetrahydrofolate reductase (MTHFR) polymorphism and platelet-receptor polymorphisms do not increase the risk of developing HIT associated thrombosis.

4 factors that affect the risk of developing HIT are noted as follows. 1) Duration of heparin treatment; long duration, up to 2 weeks is associated with the greatest risk. 2) The type of heparin involved; UFH has a greater risk than LMWH. 3) The type of patient; surgical patients are at higher risk than medical; cardiac surgical patients have the highest risk of all. 4) Females have a higher risk.

CPB bypass: The management of cardiopulmonary bypass (CPB) patients with active HIT is controversial. Direct Thrombin Inhibitors such as agatroban and hirudin are used (and increase the aPTT in a dose dependent manner). However, in the large doses required for CPB hirudin's effects cannot be monitored well. Following CPB surgery the platelet count drops to about 40-60% of normal within the first 2-3 days postop due to hemodilution and platelet consumption. But there is also a risk of HIT. 20-50% of patients develop heparin antibodies during the first 5-10 days following CPB and some develop HIT (1-3% if UFH is continued through the postop period).