Heparin is an anticoagulant which increases the blood's clotting time. Hospitalized patients at high risk for developing blood clots often receive heparin to prevent blood clots, but it is also used when patients are diagnosed with blood clots to prevent additional clot formation. Heparin is given either intravenously or subcutaneously. Although heparin is widely used, there are contraindications to its use.
Thrombocytopenia
Thrombocytopenia is a deficiency of platelets defined as when platelets fall below 150 or decrease 50 percent from baseline. Heparin-induced thrombocytopenia occurs when the body makes antibodies against platelets, thereby significantly increasing the risk of thrombosis. This decrease in platelets usually occurs within 5 to 10 days of heparin exposure, and most patients will recover 4 to 14 days after heparin is discontinued. Heparin is contraindicated in any patient with a history of severe thrombocytopenia or heparin-induced thrombocytopenia.
Uncontrolled Bleeding
Heparin is contraindicated in any patient who is actively bleeding because its mechanism of action is to increase clotting time, which would worsen bleeding complications. This is also true in cases of hemophilia or any other disorder which increases a patient's bleeding risk. Heparin should also be discontinued prior to any surgical operation or procedure to prevent bleeding complications.
Hypersensitivity
Heparin is obtained from porcine, or pig, intestines, and is standardized for use as an anticoagulant in humans. It is advised not to receive heparin if a patient has a known allergy to pork products or other animal proteins. Most hypersensitivity reactions are mild, and symptoms include itching, chills, fever or headache. In cases of a severe reaction, some people may go into anaphylactic shock, which is potentially fatal. Some individuals may also want to avoid heparin due to religious practices. Patients should speak with their doctor about this prior to receiving heparin and ask about alternatives.
Uncontrolled High Blood Pressure
Elevated blood pressure increases the risk of hemorrhagic stroke. The use of heparin in these cases is ill advised because of the increased risk of bleeding if a stroke were to occur. In cases where the blood vessels in the brain have hemorrhaged, heparin could potentially cause additional bleeding, leading to brain damage or even death. Heparin may be given once an elevated blood pressure is stabilized.
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