What laboratory tests should be ordered in a patient presenting with stroke-like symptoms?

From the Guidelines

For a patient presenting with stroke-like symptoms, I recommend ordering a comprehensive panel of laboratory tests, including blood glucose, serum electrolytes/renal function tests, complete blood count, markers of cardiac ischemia, prothrombin time/INR, activated partial thromboplastin time, and oxygen saturation, as outlined in the most recent guidelines 1. These tests are essential to aid in diagnosis and guide treatment decisions. The rationale for this comprehensive approach is that stroke-like symptoms can result from various conditions, including true ischemic or hemorrhagic stroke, metabolic derangements, infections, or toxins.

• Key laboratory tests to order include:
  • Blood glucose to rule out hypoglycemia, which can mimic stroke
  • Serum electrolytes/renal function tests to evaluate electrolytes and kidney function
  • Complete blood count to assess for anemia, infection, or platelet abnormalities
  • Markers of cardiac ischemia, such as troponin, to identify concurrent cardiac events
  • Coagulation studies, including PT/INR and PTT, to check for bleeding disorders
  • Oxygen saturation to assess for respiratory compromise Additional tests, such as urinalysis, arterial blood gas, and toxicology screen, may be necessary in selected patients, as outlined in the guidelines 1. The most recent guidelines from the American Heart Association/American Stroke Association 1 emphasize the importance of rapid identification of the underlying cause of stroke-like symptoms, as treatment approaches differ significantly. For example, thrombolytic therapy is beneficial for ischemic stroke but contraindicated in hemorrhagic stroke or stroke mimics.

From the Research

Laboratory Tests for Stroke-Like Symptoms

When a patient presents with stroke-like symptoms, several laboratory tests can be ordered to aid in diagnosis and management. These tests include:

• Complete Blood Count (CBC) to rule out infection or inflammation
• Blood chemistry tests, such as glucose and electrolyte levels, to identify potential stroke mimics like hypoglycemia
• Coagulation studies, including prothrombin time (PT) and partial thromboplastin time (PTT), to assess bleeding risks
• Troponin levels to evaluate for cardiac involvement, as elevated troponin values are frequently detected in patients with acute ischemic stroke 2
• Blood biomarkers, such as glial fibrillary acid protein (GFAP), retinol binding protein 4 (RBP-4), N-terminal proB-type natriuretic peptide (NT-proBNP), and endostatin, to differentiate between ischemic and hemorrhagic strokes 3

Neuroimaging Studies

Neuroimaging studies are essential to differentiate between ischemic and hemorrhagic strokes, as well as to diagnose other conditions that may mimic stroke. These studies include:

• Noncontrast head computed tomography (CT) to quickly identify hemorrhagic strokes
• Magnetic resonance imaging (MRI) to provide more detailed images of the brain and identify ischemic strokes
• Cerebrospinal fluid inspection for bilirubin to diagnose subarachnoid hemorrhage if CT results are normal 4

Other Diagnostic Tests

Other diagnostic tests that may be ordered in patients with stroke-like symptoms include:

• Electrocardiogram (ECG) to evaluate for cardiac arrhythmias or ischemia
• Echocardiogram to assess cardiac function and identify potential sources of embolism
• Carotid ultrasound to evaluate for carotid artery stenosis or occlusion 5, 6