From the Guidelines
For elderly patients with stroke, a focused hypercoagulable workup on an inpatient basis should include complete blood count, prothrombin time/INR, activated partial thromboplastin time, fibrinogen level, protein C and S activity, antithrombin III activity, factor V Leiden mutation, prothrombin gene mutation, antiphospholipid antibodies (including lupus anticoagulant, anticardiolipin antibodies, and beta-2 glycoprotein antibodies), and homocysteine levels, as recommended by the American Heart Association/American Stroke Association guideline 1.
This targeted approach is recommended because hypercoagulable states, while less common causes of stroke in the elderly compared to traditional risk factors, can still contribute to stroke pathogenesis in select patients. The yield of testing for a hypercoagulable state is low for patients >50 years of age, but it is still important to identify these conditions to avoid misdirected ineffective or harmful therapies 1.
Key points to consider when interpreting the results of the hypercoagulable workup include:
- Acute phase reactants may affect some test results, so protein C, protein S, and antithrombin III levels might be falsely decreased during the acute stroke period.
- If the patient is already on anticoagulation therapy, this will impact test interpretation.
- The workup should be tailored based on clinical suspicion, family history, and the absence of traditional stroke risk factors.
- Results should be interpreted in the context of the patient's overall clinical picture, as incidental findings may not necessarily indicate causation of the stroke event.
In terms of specific tests, the following are recommended:
- Complete blood count to evaluate for thrombocytosis or thrombocytopenia
- Prothrombin time/INR and activated partial thromboplastin time to evaluate for coagulopathy
- Fibrinogen level to evaluate for hypofibrinogenemia
- Protein C and S activity, antithrombin III activity, factor V Leiden mutation, and prothrombin gene mutation to evaluate for inherited thrombophilias
- Antiphospholipid antibodies (including lupus anticoagulant, anticardiolipin antibodies, and beta-2 glycoprotein antibodies) to evaluate for antiphospholipid syndrome
- Homocysteine levels to evaluate for hyperhomocysteinemia
It is also important to note that the American Heart Association/American Stroke Association guideline recommends that diagnostic evaluation for stroke should be completed or underway within 48 hours of onset of stroke symptoms 1.
Overall, a focused hypercoagulable workup is an important part of the diagnostic evaluation for elderly patients with stroke, and can help identify underlying conditions that may contribute to stroke pathogenesis.
From the Research
Hypercoagulable Labs for Stroke in the Elderly
The following hypercoagulable labs can be done on an inpatient basis for stroke in the elderly:
- Prothrombin time (PT) 2
- Partial thromboplastin time (PTT) 2, 3
- Platelet count 3
- Fibrinogen levels 3
- D-dimer levels 3, 4
- Thrombin-antithrombin complex (TAT) 4
- Plasminogen activator inhibitor-1 (PAI-1) 4
- Protein C activity 4
Rationale for Lab Selection
These labs are selected based on their ability to predict abnormal coagulation in ischemic stroke 2 and their association with poor prognosis in patients with traumatic brain injury 3 and sepsis 4. The guidelines for the early management of patients with acute ischemic stroke also support the use of these labs in the in-hospital management of stroke patients 5.
Limitations
While these labs can provide valuable information on the coagulation status of elderly stroke patients, it is essential to note that the evidence for their use is based on studies with varying populations and outcomes. Therefore, the results should be interpreted in the context of each patient's individual clinical presentation and medical history.