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 

---

NDA 17-037/S-158 
Page 26 
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 anticoagulant 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 anticoagulation.