What routine lab tests are recommended for a patient with stenosis of the posterior cerebral artery?

Routine Laboratory Testing for Posterior Cerebral Artery Stenosis

All patients with posterior cerebral artery stenosis require a comprehensive metabolic and hematologic workup within 48 hours to identify modifiable atherosclerotic risk factors and guide secondary prevention strategies. 1

Essential Initial Blood Work

The following laboratory tests must be obtained as part of the diagnostic evaluation:

Complete Blood Count and Coagulation Studies

• Complete blood count (CBC) with platelet count to evaluate for polycythemia, thrombocytosis, anemia, or thrombocytopenia that may contribute to thrombotic risk 1, 2
• Prothrombin time (PT) and International Normalized Ratio (INR) to assess baseline coagulation status, particularly if antiplatelet therapy or anticoagulation is being considered 1, 2
• Activated partial thromboplastin time (aPTT) to complete the coagulation profile 1, 2

Metabolic and Renal Function

• Serum creatinine and estimated glomerular filtration rate (eGFR) to assess renal function, which guides medication dosing and identifies another vascular risk factor 1, 2
• Serum electrolytes to identify metabolic disturbances 2
• Random or fasting glucose to screen for acute hyperglycemia or hypoglycemia 1, 2

Lipid Profile Assessment

• Fasting or non-fasting lipid profile including total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides 1, 2
  • This is critical because high-dose statin therapy targeting LDL <70 mg/dL (1.8 mmol/L) is recommended for intracranial atherosclerotic disease 1
  • HDL-cholesterol elevation is associated with prevention of angiographic progression of symptomatic intracranial stenosis 3

Diabetes Screening

• Glycated hemoglobin (HbA1c) to screen for diabetes mellitus, a major modifiable stroke risk factor 1, 2
• If HbA1c is borderline, a 75g oral glucose tolerance test should be performed 2

Cardiac Biomarkers

• Troponin to evaluate for concurrent acute coronary syndrome, as cardiovascular disease frequently coexists with cerebrovascular disease 2

Critical Timing Considerations

The diagnostic evaluation should be started or ideally completed within 48 hours of symptom onset, as patients with intracranial atherosclerotic disease have a high early recurrent stroke risk 1, 2. For high-risk patients presenting within 48 hours, all bloodwork should be completed within 24 hours as part of urgent hospitalization 2.

Integration with Other Diagnostic Studies

Blood work must be obtained concurrently with:

• 12-lead ECG to screen for atrial fibrillation 1, 2
• Brain imaging (CT or MRI) to exclude hemorrhage and identify infarction 1, 2
• Vascular imaging (CTA, MRA, or carotid ultrasound) to characterize the stenosis and identify other vascular lesions 1, 2

Common Pitfalls to Avoid

• Do not delay laboratory testing beyond 48 hours, as this represents a critical window for risk stratification and treatment initiation 1, 2
• Do not omit lipid profile testing even if the patient reports recent normal values, as aggressive lipid management with target LDL <70 mg/dL is mandatory for intracranial atherosclerotic disease 1
• Do not confuse atherosclerotic intracranial stenosis with cardioembolic mechanisms—PCA stenosis requires treatment as an atherosclerotic process with antiplatelet therapy and intensive risk factor modification 4