Heparin, whether therapeutic or as a contaminant from an intravenous line, works by potentiating antithrombin, which inactivates thrombin (Factor IIa) and Factor Xa. Thrombin is the final enzyme that converts fibrinogen to fibrin. The Thrombin Time (TT) test directly measures this final step by adding exogenous thrombin to plasma. Even tiny amounts of heparin can dramatically inhibit this added thrombin, causing a very prolonged TT. In contrast, the APTT is also sensitive to heparin but requires the intrinsic pathway activation, and the PT is the least sensitive. If heparin contamination is suspected, a reptilase time (which uses snake venom not inhibited by heparin) can be run; it will be normal, confirming the presence of heparin as the cause of the prolonged TT.

Break down complex topics into smaller, manageable chunks for easier recall.

Zambia

• Joseph Soko – 101 pts

• Visual Pathway Lesions
• Positive and Negative Symptoms
• Hallucinations and Delusions
• Antipsychotic Medications
• Emergency: Environmental Emergencies