Which laboratory tests should be obtained for an adult acute ischemic stroke patient being evaluated for thrombolysis, including CBC with differential, basic metabolic panel (electrolytes, renal function, calcium), serum glucose, PT/INR, aPTT, anticoagulant‑specific levels if on warfarin or direct oral anticoagulants, lipid profile, HbA1c, cardiac troponin, 12‑lead ECG, serum β‑hCG if female of child‑bearing potential, ESR and CRP if vasculitis is suspected, urine toxicology if drug use is suspected, and blood cultures if infection is indicated?

Laboratory Tests for Adult Acute Ischemic Stroke Evaluation

All adult patients with suspected acute ischemic stroke being evaluated for thrombolysis should immediately receive: complete blood count with platelets, basic metabolic panel (electrolytes, renal function), serum glucose, PT/INR, aPTT, cardiac troponin, and 12-lead ECG. 1

Core Laboratory Panel (All Patients)

Immediate Priority Tests

• Blood glucose must be checked immediately as hypoglycemia can mimic stroke symptoms and requires urgent exclusion before any other intervention 1
• Complete blood count with platelet count is essential to detect thrombocytopenia (which contraindicates thrombolysis), anemia, or polycythemia that could influence treatment decisions 1
• Serum electrolytes and renal function tests (including creatinine) identify metabolic derangements that can mimic stroke and guide medication dosing 1
• PT/INR and aPTT are critical to identify coagulopathies, especially in patients on warfarin or with suspected bleeding abnormalities 1
• Cardiac troponin identifies concurrent myocardial infarction or ischemia, as acute MI can cause stroke and stroke can precipitate myocardial ischemia 1
• 12-lead ECG is mandatory to detect atrial fibrillation, atrial flutter, or acute myocardial infarction 1
• Oxygen saturation should be monitored continuously 1

Critical Timing Consideration for Thrombolysis

Thrombolytic therapy should NOT be delayed while awaiting coagulation results (PT/INR, aPTT, platelet count) UNLESS: 1

1. There is clinical suspicion of bleeding abnormality or thrombocytopenia
2. The patient has received heparin or warfarin
3. Anticoagulant use is uncertain

Additional Tests for Specific Clinical Scenarios

For Patients on Anticoagulation

• Anticoagulant-specific levels should be obtained if the patient is on direct oral anticoagulants (DOACs) 2
  • Calibrated anti-Xa activity for apixaban, edoxaban, rivaroxaban
  • Hemoclot assay for dabigatran
  • Levels <50 ng/mL support thrombolysis consideration; levels >100 ng/mL exclude thrombolysis 2
• INR ≥2.0 makes ischemia far less likely in warfarin patients; no patient with INR ≥3.6 had ischemia in validation studies 3

For Selected Patients Based on Clinical Suspicion

• Hepatic function tests if liver dysfunction is suspected or patient is on warfarin 1
• Toxicology screen and blood alcohol level if drug or alcohol use is suspected 1
• Pregnancy test (serum β-hCG) for females of childbearing potential 1
• Arterial blood gas only if hypoxia is suspected 1
• Chest radiography only if lung disease is clinically suspected (routine chest X-ray altered management in only 3.8% of stroke patients) 1
• Lumbar puncture only if subarachnoid hemorrhage is suspected and CT scan is negative for blood 1
• ESR and CRP only if vasculitis is specifically suspected (not routine) 4

Secondary Risk Stratification Tests (Within 48 Hours)

• Lipid profile for cardiovascular risk assessment 5, 6
• HbA1c for diabetes screening if not already obtained 5, 6
• Extended cardiac monitoring for at least 14 days if initial ECG shows no atrial fibrillation but embolic mechanism is suspected 5, 7, 6

Common Pitfalls to Avoid

• Never delay thrombolysis for routine coagulation studies unless specific contraindications exist (known anticoagulant use, clinical bleeding suspicion, or thrombocytopenia) 1
• Do not skip glucose testing - it is the only stroke mimic requiring immediate exclusion 1, 6
• Do not order routine chest X-ray unless clinically indicated by respiratory symptoms 1
• Do not delay treatment for HbA1c, lipid profile, or other secondary tests - these can be obtained after acute management 5
• Label specimens STAT if patient is within thrombolysis window to expedite processing 1