Laboratory Tests for Patients with History of Stroke
For patients with a history of stroke, a comprehensive laboratory evaluation should include blood glucose, serum electrolytes, renal function tests, complete blood count with platelet count, coagulation studies, lipid profile, and cardiac markers to identify risk factors and guide secondary prevention strategies. 1
Core Laboratory Tests for All Stroke Patients
Essential Blood Tests
- Blood glucose: Identifies diabetes/hyperglycemia (associated with poor outcomes) or hypoglycemia (can mimic stroke)
- Complete blood count with platelet count: Detects anemia, thrombocytopenia, or other hematologic abnormalities
- Coagulation studies:
- Prothrombin time (PT)/International Normalized Ratio (INR)
- Activated partial thromboplastin time (aPTT)
- Serum electrolytes and renal function tests: Assess fluid/electrolyte status and kidney function
- Fasting or non-fasting lipid profile: Measures total cholesterol, LDL, HDL, and triglycerides 1
- HbA1c: Evaluates long-term glycemic control 1
Cardiac Assessment
- Cardiac markers: Evaluate for concurrent cardiac ischemia
- 12-lead ECG: Screen for atrial fibrillation, atrial flutter, and other cardiac conditions 1
Additional Tests Based on Clinical Scenario
For Patients with Cryptogenic Stroke
- Hypercoagulable panel: Consider testing for inherited or acquired thrombophilias 1
- Inflammatory markers: ESR, CRP, and other markers of systemic inflammation 1, 2
- Infectious disease screening: Consider HIV, syphilis testing if clinically indicated 1
- Toxicology screen: Particularly for younger patients or when substance abuse is suspected 1, 2
For Specific Patient Populations
- Pregnancy test: For women of childbearing age 1
- Hepatic function tests: Particularly important before starting statins 1
- Arterial blood gas: If hypoxia is suspected 1
Timing of Laboratory Testing
Laboratory testing should be completed as soon as possible, with results available within 48 hours of stroke onset to guide secondary prevention strategies 1. For patients being considered for acute interventions like thrombolysis, certain tests (CBC, coagulation studies) should be expedited but should not delay treatment unless there is:
- Clinical suspicion of bleeding abnormality or thrombocytopenia
- Patient has received anticoagulants
- Anticoagulant use is unknown 1
Monitoring Considerations
After initial laboratory assessment, follow-up testing should be conducted to:
- Monitor medication effects (e.g., lipid levels with statin therapy)
- Assess for new risk factors
- Evaluate therapeutic targets (e.g., LDL <100 mg/dL) 3
Clinical Pitfalls to Avoid
- Don't overlook metabolic causes: Electrolyte abnormalities can mimic stroke symptoms 1
- Don't delay thrombolytic therapy while waiting for non-critical lab results in acute settings 1
- Don't miss cardiac sources of embolism: Many stroke patients have concurrent cardiac conditions 1
- Don't forget to assess modifiable risk factors: Hypertension, diabetes, and dyslipidemia are major contributors to stroke risk 4
- Don't neglect follow-up testing: Many patients remain above their target LDL goals even after stroke 3
By following this structured laboratory assessment approach, clinicians can identify risk factors, guide secondary prevention strategies, and potentially reduce the risk of recurrent stroke.