A Balancing Act: anticoagulation in bleeding disorders

By Amera Hassan

Case

History

42 year-old female with a past medical history including immune thrombocytopenic purpura (ITP) diagnosed during pregnancy, systemic lupus erythematosus (SLE), antiphospholipid syndrome, and anemia on hydroxychloroquine, methotrexate, and prednisone who presented to primary care clinic with several weeks of left lower extremity pain. At her primary clinic, an ultrasound revealed a deep venous thrombus of the left popliteal vein and tibioperoneal trunk as well as incomplete thrombus of the left peroneal vein. She was sent to the ED. In the ED, patient denied any recent travel or immobilization but did endorse a recent upper respiratory tract illness.

Initial vitals

BP 114/67 | Pulse 98 | Temp 37.9 °C (100.2 °F) | Resp 18 | SpO2 98% on room air

Examination

Constitutional: resting in bed, in no acute distress

Cardiovascular: regular rate and rhythm, good pulses in all extremities

Respiratory: breathing comfortably on room air, clear lung fields bilaterally

Musculoskeletal: warm extremities, symmetric extremities without redness or swelling

Laboratory results

CBC

White Blood Cell Count 1.58 (ref 4.50-11.0) K/cu mm

Hemoglobin 8.5 (ref 12.0-15.0) g/dL

Platelet count 123 (ref 150-350) K/cu mm

Mean Corpuscular Volume 90.1 (ref 80.0-100.0) fL

Absolute neutrophil count 1.13 (ref 1.50-7.80) K/cu mm

Absolute lymphocyte count 0.26 (ref 1.10-4.80) K/cu mm

Inflammatory Markers

Erythrocyte sedimentation rate 74 (ref <20) mm/hr

C-Reactive Protein 2.21 (ref <0.29) mg/dL

Imaging

CTA Chest: No evidence of pulmonary embolism. Mild cardiomegaly. Trace pericardial effusion, trace left pleural effusion and mild pulmonary edema.

ED and hospital course

Patient was started on standard heparin bolus and drip. She was also admitted for further investigation of her cytopeniae and subacute fever.

Clinical question: what is the management of thromboembolic disease in patients with a history of thrombocytopenia, particularly immune thrombocytopenic purpura?

Patients with thrombocytopenia remain at substantial risk for thromboembolic disease despite low platelet counts (1). In fact, lower platelet counts may pose an increased risk for thromboembolism, possibly due to platelet hyperreactivity and antiphospholipid antibodies, though the exact mechanism remains under investigation (2). Unfortunately, there is no anticoagulant that can dissolve a thrombus without increasing bleeding risk. Because of the tenuous balance between the risk of bleeding and clotting, and the deficit of research on patients with platelets less than 50,000/mL, therapeutic anticoagulation in patients with thrombocytopenia poses a unique challenge. Though no definitive formula has been established to quantify the opposing risks, there are several recommendations that remain to consider.

Summary of evidence

Much of the evidence available comes from studies on cancer patients, who typically exhibit a hypercoagulable state. The American Society of Hematology developed a guideline supported by systematic evidence to make recommendations, many of which can be extrapolated to thrombocytopenic patients with thrombosis (3). In general, anticoagulation is contraindicated in platelet counts between 50,000-75,000/mL (4). The algorithm in Figure 1, however, explores beyond the threshold of contraindication using the WHO bleeding scale to stratify risk and management (5).

Other considerations

- Consider corticosteroids and IVIg to raise platelet counts to a safe level (>30,000mL) (5)

- Consider thrombopoietin-receptor agonists to transiently increase platelet counts (6)

- Be cautious as platelet transfusion may increase risk of venous and arterial thrombosis (7)

- Forgo or adjust initial heparin bolus to avoid transient over-anticoagulation (8)

- Consider unfractionated heparin for its short half-life and easy reversibility; LMWH may be used after successful trial of unfractionated heparin (8)

- Consider half-therapeutic dose for low-risk thromboses such as distal DVTs and incidental subsegmental PEs (9)

- Investigate platelet function and coagulation in patients with kidney and liver dysfunction respectively (10)

- Older individuals (>45) are typically at a higher risk of fall and thus severe bleeding on anticoagulation may occur (11)

References

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