Description

Thrombocytopenia 
Thrombocytopenia has been reported to occur in patients receiving heparin with a reported incidence 
of 0 to 30%. Platelet counts should be obtained at baseline and periodically during heparin 

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NDA 17-037/S-158 
Page 16 
administration. Mild thrombocytopenia (count greater than 100,000/mm
3
) may remain stable or reverse 
even if heparin is continued. However, thrombocytopenia of any degree should be monitored closely. 
If the count falls below 100,000/mm
3
or if recurrent thrombosis develops (see Heparin-induced 
Thrombocytopenia and Heparin-induced Thrombocytopenia and Thrombosis), the heparin product 
should be discontinued and, if necessary, an alternative anticoagulants administered.
 
Heparin-induced Thrombocytopenia (HIT) and Heparin-induced Thrombocytopenia and 
Thrombosis (HITT) 
Heparin-induced Thrombocytopenia (HIT) is a serious antibody-mediated reaction resulting 
from irreversible aggregation of platelets. HIT may progress to the development of venous and 
arterial thromboses, a condition referred to as Heparin-induced Thrombocytopenia and 
Thrombosis (HITT). Thrombotic events may also be the initial presentation for HITT. These 
serious thromboembolic events include deep vein thrombosis, pulmonary embolism, cerebral 
vein thrombosis, limb ischemia, stroke, myocardial infarction, mesenteric thrombosis, renal 
arterial thrombosis, skin necrosis, gangrene of the extremities that may lead to amputation, and 
possibly death. Thrombocytopenia of any degree should be monitored closely. If the platelet 
count falls below 100,000/mm
3 
or if recurrent thrombosis develops, the heparin product should 
be promptly discontinued and alternative anticoagulants considered if patients require continued