Heparin-induced thrombocytopenia history and symptoms

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 history and symptoms 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 history and symptoms 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 history and symptoms
CDC on Heparin-induced thrombocytopenia history and symptoms
Heparin-induced thrombocytopenia history and symptoms in the news
Blogs on Heparin-induced thrombocytopenia history and symptoms
Directions to Hospitals Treating Heparin-induced thrombocytopenia
Risk calculators and risk factors for Heparin-induced thrombocytopenia history and symptoms

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.B.B.S. [2] Shyam Patel [3]

Overview

Heparin-induced thrombocytopenia is diagnosed when the platelet count falls by > 50% typically after 5-10 days of heparin therapy. It is a clinicopathologic diagnosis and early diagnosis and management may be life saving. Unlike other immune mediated thrombocytopenia (idiopathic thrombocytopenic purpura), the levels of platelet stays > 20,000 microl, thus frank clinical bleeding is less common in HIT when compared to other conditions, where the platelet may fall below 10,000/ microl.

History

Heparin therapy

The history of HIT always includes exposure to heparin or heparinoids.

• Classic HIT: This occurs typically after 5-10 days of initiation of heparin or heparin-like therapy. Onset of HIT after 2 weeks of heparin therapy is uncommon. Earlier onset of HIT is usually seen in patients who have been previously treated with heparin (1-3 months prior) and have circulating HIT antibodies. In these patients the median time of platelet fall is less than 12 hours after the start of heparin administration. Patients will typically have low platelet counts and possibly thrombosis.

• Delayed onset HIT: This occurs after heparin has been withdrawn (median time of 14 days after heparin withdrawal). Patients will typically have low platelet counts and possibly thrombosis.

Recent Surgery

Patients with HIT often have a history of a recent cardiac or orthopedic surgery. They may develop low platelet count and deep vein thrombosis or other thrombotic manifestation.

• In cardiac surgery patients, decrease in the platelet count by > 50 % can occur within 3 days of surgery. This may be attributed to prolonged contact of platelets with the artificial surface and administration of large amount of unfractionated heparin (UFH). However, a diagnosis of HIT is more probable if a fall in the platelet counts ≥50 % is seen after 5-10 days of heparin therapy. Note that a history of surgery is not required as part of the history of HIT. Some patients with no surgical history will develop HIT.

Symptoms

Patients can present with symptoms suggestive of arterial and venous thrombosis. The increased incidences of thrombosis may be attributed to:

• Release of procoagulants by activated platelets
• Release of platelet membranes that in turn activates coagulation pathways
• Binding and activation of HIT antibodies to endothelial cells resulting in release of tissue factor and thrombin

Venous thrombosis

• Leg pain: This is a common manifestation of deep vein thrombosis. It typically occurs in the calf muscles. Homan's sign is pain on dorsiflexion of the calf.
• Leg swelling: This is a common manifestation of deep vein thrombosis. Swelling is due to obstruction of venous return and dilation of the surface veins.
• Leg erythema: This is a common manifestation of deep vein thrombosis.
• Dyspnea (new or worsening): This is a common manifestation of pulmonary embolism.
• Pleuritic chest pain: This can be a manifestation of pulmonary embolism.
• Sustained hypotension: This can be a manifestation of a massive pulmonary embolism.

Arterial thrombosis

The symptoms of arterial thrombosis are variable and depend on the organ involved. It can present itself as stroke, myocardial infarction, peripheral arterial occlusion, or end organ infarction (for example, renal dysfunction from renal artery occlusion).

Limb gangrene

This can be seen in both upper and lower extremities. However, lower extremities are more common compared to upper.

Skin necrosis

Skin necrosis is commonly seen in the abdomen, distal extremities, and nose.

• Redness of skin
• Purpura
• Bleeding from the skin

Bleeding

Bleeding can occur in the setting of thrombocytopenia. Spontaneous bleeding usually does not occur unless the platelet count is less than 10000 per microliter. Bleeding can occur at platelet counts below 50000 per microliter if a patient is undergoing an invasive procedure or experiences trauma.