What labs should be checked before administering Tenecteplase (TNK)?

Laboratory Tests Required Before Administering Tenecteplase (TNK)

Before administering tenecteplase (TNK), a comprehensive coagulation panel including activated partial thromboplastin time (aPTT), prothrombin time/international normalized ratio (PT/INR), complete blood count with platelet count, and creatinine should be obtained to assess bleeding risk and ensure safe administration. 1, 2

Essential Laboratory Tests

• Complete blood count (CBC) with platelet count to identify thrombocytopenia which may increase bleeding risk 1, 2
• Coagulation parameters including activated partial thromboplastin time (aPTT) and prothrombin time/international normalized ratio (PT/INR) to identify underlying coagulopathies 1
• Serum creatinine and blood urea nitrogen (BUN) to assess kidney function, as renal impairment may affect drug clearance 1, 2
• Blood glucose level to rule out hypoglycemia as a stroke mimic 1
• Troponin to rule out concurrent myocardial infarction 1

Additional Important Tests

• Hematocrit and hemoglobin to establish baseline values before potential hemorrhagic complications 1, 2
• Electrolytes to assess for metabolic abnormalities that may mimic stroke symptoms 1
• Liver function tests when indicated to assess hepatic function 1
• Pregnancy test in women of childbearing age, as pregnancy considerations may affect treatment decisions 2

Timing Considerations

• All laboratory tests should be obtained urgently but should not delay TNK administration in eligible stroke patients 1
• If the patient was receiving heparin therapy before screening, an aPTT must be performed with a result less than 1.5 times the upper limit of normal before TNK administration 1

Clinical Pitfalls to Avoid

• Do not delay thrombolysis waiting for non-essential laboratory results in patients with acute ischemic stroke when time-to-treatment is critical 1
• Remember that laboratory values obtained after TNK administration may be unreliable due to the fibrinolytic activity of tenecteplase in blood samples 2
• Be aware that patients with abnormal coagulation parameters have increased risk of hemorrhagic complications 1, 2
• Consider that elderly patients (≥65 years) have higher rates of intracranial hemorrhage and major bleeds requiring blood transfusion 2

Contraindications Based on Laboratory Results

• Active internal bleeding or recent (within 3 weeks) significant bleeding 1
• Known bleeding disorders 1
• INR >1.7 in patients on oral anticoagulants 1
• Platelet count <100,000/mm³ 1
• Severe uncontrolled hypertension (systolic blood pressure >180 mmHg) 1

By ensuring these laboratory tests are performed and reviewed before administering tenecteplase, clinicians can minimize the risk of adverse events while providing timely thrombolytic therapy for appropriate patients.