Should heparin (unfractionated heparin) be discontinued in an inpatient with thrombocytopenia (platelet count of 75)?

From the Guidelines

Yes, you should discontinue heparin if the platelet count is 75,000/μL or lower. This level represents a significant drop in platelets that could indicate heparin-induced thrombocytopenia (HIT), a serious immune-mediated adverse reaction to heparin therapy. According to the most recent guidelines, immediate interruption of heparin is recommended in case of thrombocytopenia < 100,000/mL (or > 50% relative drop from baseline platelet count) occurring during treatment 1.

After stopping heparin, notify the healthcare team immediately and consider ordering a HIT antibody test to confirm the diagnosis. Do not substitute with low molecular weight heparin (LMWH) as cross-reactivity can occur. If anticoagulation is still necessary, non-heparin alternatives such as direct thrombin inhibitors (argatroban, bivalirudin) or fondaparinux should be considered, as suggested by the American College of Chest Physicians evidence-based clinical practice guidelines 1.

Key considerations in managing thrombocytopenia include:

• Monitoring platelet count daily until recovery begins
• Avoiding heparin re-exposure due to the risk of cross-reactivity
• Using non-heparin anticoagulants in case of documented or suspected HIT, as recommended by the European Society of Cardiology guidelines 1
• Being aware of the potential for life-threatening complications, including stroke, pulmonary embolism, or limb ischemia, despite the low platelet count, which paradoxically increases thrombosis risk rather than bleeding risk.

From the FDA Drug Label

If the platelet count falls below 100,000/mm3 or if recurrent thrombosis develops, promptly discontinue heparin, evaluate for HIT and HITT, and, if necessary, administer an alternative anticoagulant. Obtain platelet counts before and periodically during heparin therapy. Monitor thrombocytopenia of any degree closely If the count falls below 100,000/mm3 or if recurrent thrombosis develops, promptly discontinue heparin, evaluate for HIT and HITT, and, if necessary, administer an alternative anticoagulant [see Warnings and Precautions (5.3)].

The patient's platelet count is 75, which is below the threshold of 100,000/mm3. Discontinue heparin and evaluate for HIT and HITT, and consider administering an alternative anticoagulant if necessary 2.

From the Research

Heparin-Induced Thrombocytopenia (HIT) Diagnosis and Treatment

• The diagnosis of HIT is based on the "4 Ts": thrombocytopenia, timing of platelet count fall, thrombosis or other complications, and other causes for thrombocytopenia 3.
• A drop in platelet count to less than 50% of the basal level, with or without the appearance of thrombotic complications, is a key symptom of HIT 4.
• The timing of the thrombocytopenia in relation to the initiation of heparin therapy is critically important, with the platelet count beginning to drop within 5 to 10 days of starting heparin 5.

Discontinuation of Heparin and Alternative Anticoagulants

• When HIT is suspected, it is essential to discontinue all heparin products 3, 4, 5, 6, 7.
• Alternative anticoagulants, such as lepirudin, argatroban, bivalirudin, or fondaparinux, should be initiated 3, 5, 6.
• Warfarin therapy should not be initiated until the platelet count has recovered and the patient is systemically anticoagulated 5, 7.

Platelet Count and Heparin Discontinuation

• A platelet count of 75 is considered thrombocytopenic, and heparin should be discontinued if HIT is suspected 3, 4, 5, 6, 7.
• The decision to discontinue heparin should be based on the clinical diagnosis of HIT, which can be supported by laboratory testing for HIT antibodies 3, 4, 5, 6, 7.