What are the recommended laboratory tests for hypercoagulability (coagulation disorders) that can be performed on an inpatient basis for ischemic stroke in young adults?

From the Guidelines

For young stroke patients, a comprehensive inpatient hypercoagulable workup is recommended, including antiphospholipid antibody panel, protein C and S levels, antithrombin III, factor V Leiden mutation, prothrombin gene mutation (G20210A), homocysteine levels, and methylenetetrahydrofolate reductase (MTHFR) gene testing, as supported by the 2021 guideline for the prevention of stroke in patients with stroke and transient ischemic attack 1. This workup should also include complete blood count with peripheral smear, comprehensive metabolic panel, lipid profile, hemoglobin A1C, and inflammatory markers like ESR and CRP. Key considerations in the workup include:

• Timing of tests, as acute stroke and anticoagulation therapy can affect results, with protein C, protein S, and antithrombin III levels potentially being falsely low during acute thrombosis or while on heparin/warfarin 1.
• The potential need to repeat certain tests 2-3 months after the acute event and after discontinuation of anticoagulation for accurate results.
• Genetic tests like Factor V Leiden and prothrombin gene mutation are not affected by timing or medications. This comprehensive approach is crucial for identifying hypercoagulable states in young stroke patients, which can significantly impact treatment decisions and secondary prevention strategies, particularly in those under 50 years old, as highlighted in the guidelines 1. Additionally, the yield of testing for hypercoagulable states is generally low in patients over 50 years of age, making targeted testing based on clinical suspicion and demographic variables essential 1. The importance of a thorough initial evaluation, including assessment of airway, breathing, and circulation, neurological examination, and basic testing such as electrocardiogram and acute blood work, is also emphasized in guidelines for hyperacute stroke care 1.

From the Research

Laboratory Tests for Hypercoagulability in Ischemic Stroke

The following laboratory tests can be performed on an inpatient basis to evaluate hypercoagulability in young adults with ischemic stroke:

• Prothrombin time (PT) 2
• Partial thromboplastin time (PTT) 2, 3
• Thrombin time 3
• Fibrinogen level 3, 4
• Factor V and VIII levels 3
• Antithrombin III level 3
• Protein C and S levels 5, 3
• D-dimer level 4
• Acquired hyperhomocysteinemia testing 5
• Factor V Leiden mutation testing 5
• Methyl-tetrahydro-folate-reductase (MTHFR) C677T mutation testing 5
• Anticardiolipin antibodies testing 5
• Lupus anticoagulant testing 5
• Thrombocytosis evaluation 5
• G20210A prothrombin gene mutation testing 5

Timing and Storage of Blood Samples

When performing these laboratory tests, it is essential to consider the timing and storage of blood samples to ensure accurate results:

• Blood samples should be stored at 6 degrees C to maintain the stability of coagulation analytes 3
• Prothrombin time and activated partial thromboplastin time should be measured within 24 hours of blood sample collection 3
• Fibrinogen and antithrombin III levels can be measured up to 7 days after blood sample collection 3
• Factor V and VIII levels should be measured within 8 hours of blood sample collection 3