Does a drop in hemoglobin (Hb) level due to heparin (unfractionated heparin) therapy necessitate discontinuation of the heparin infusion in a patient requiring a blood transfusion?

From the Guidelines

Discontinuation of heparin is strongly recommended if the patient's hemoglobin drop is suspected to be due to heparin-induced thrombocytopenia (HIT) or heparin-induced bleeding, as indicated by the American Society of Hematology 2018 guidelines 1. When a patient's hemoglobin level drops on heparin and requires a transfusion, the decision to discontinue the heparin drip depends on the underlying cause of the hemoglobin decrease.

Clinical Context Considerations

• If the hemoglobin drop is due to heparin-induced bleeding, the heparin should be immediately discontinued.
• If the hemoglobin decrease is unrelated to heparin (such as from surgery, gastrointestinal bleeding, or other causes), and the patient still requires anticoagulation, the heparin may be continued with careful monitoring.
• When heparin-induced thrombocytopenia (HIT) is suspected—characterized by a significant platelet drop typically 5-10 days after starting heparin—the drug should be stopped immediately and an alternative anticoagulant like argatroban or bivalirudin initiated, as suggested by the ASH guideline panel 1.

Monitoring and Reassessment

During any transfusion, more frequent monitoring of hemoglobin, platelets, and coagulation parameters (PTT/anti-Xa levels) is essential. The underlying reason for anticoagulation should be reassessed, weighing the risk of thrombosis against the risk of bleeding. In cases where anticoagulation remains necessary despite bleeding risk, consider reducing the heparin dose or switching to a less intensive regimen after the transfusion is complete and hemoglobin has stabilized.

Alternative Anticoagulants

The choice of alternative anticoagulant may be influenced by drug factors (availability, cost, ability to monitor the anticoagulant effect, route of administration, and half-life), patient factors (kidney function, liver function, bleeding risk, and clinical stability), and experience of the clinician, as outlined in the guidelines 1. In patients with critical illness, increased bleeding risk, or increased potential need for urgent procedures, argatroban or bivalirudin may be preferred because of shorter duration of effect, as suggested by the ASH guideline panel 1.

From the FDA Drug Label

5.2 Hemorrhage Avoid using heparin in the presence of major bleeding, except when the benefits of heparin therapy outweigh the potential risks. An unexplained fall in hematocrit, fall in blood pressure or any other unexplained symptom should lead to serious consideration of a hemorrhagic event.

If a patient's hemoglobin level drops on heparin and requires a transfusion, discontinue the heparin drip if the bleeding is suspected to be heparin-related, as the benefits of heparin therapy may no longer outweigh the potential risks.

• Monitor the patient closely for signs of hemorrhage and consider alternative anticoagulant therapy if necessary.
• Evaluate the patient for heparin-induced thrombocytopenia (HIT) and heparin-induced thrombocytopenia with thrombosis (HITT) if the platelet count falls below 100,000/mm3 or if recurrent thrombosis develops 2.

From the Research

Heparin-Induced Thrombocytopenia (HIT) and Heparin Discontinuation

• The decision to discontinue heparin in a patient with a dropping hemoglobin level who requires a transfusion is complex and depends on the clinical suspicion of heparin-induced thrombocytopenia (HIT) 3, 4.
• If HIT is suspected, prompt suspension of heparin is necessary, followed by initiation of non-heparin anticoagulant therapy 5.
• The diagnosis of HIT requires a stepwise approach, including the use of risk-stratification tools and laboratory assays 3, 4.

Management of HIT

• The management of HIT involves the selection and use of nonheparin anticoagulation, taking into account the patient's increased thrombotic risk and possible concurrent increased bleeding risk due to thrombocytopenia 3, 6.
• Alternative anticoagulation options include argatroban, fondaparinux, and direct oral anticoagulants (DOACs), with argatroban being the only FDA-approved treatment for HIT in both the US and Europe 5.
• The choice of anticoagulant and dosing strategy should be individualized based on patient characteristics and institutional resources 3, 6.

Transfusion and Anticoagulation

• The need for transfusion in a patient with a dropping hemoglobin level on heparin does not necessarily require discontinuation of heparin, but rather a careful assessment of the patient's overall clinical condition and the risk of bleeding and thrombosis 7.
• The use of anticoagulation protocols, such as activated clotting time (ACT)-guided or activated partial thromboplastin time (aPTT)-guided heparin anticoagulation, may influence the incidence of bleeding and thrombosis, as well as the need for transfusion 7.