In Rosie's case, prolonged PT and PTT most strongly point to which toxin exposure?

• A. Rodenticide (anticoagulant)
• B. Acetaminophen
• C. Ethylene glycol
• D. Vitamin K deficiency from diet

Answer: (A)

Prolonged PT and PTT both point to problems with vitamin K–dependent clotting factors (II, VII, IX, X). The toxin that best creates this pattern is an anticoagulant rodenticide, which blocks vitamin K recycling and thus depletes those factors. Because factor VII has the shortest half-life, the extrinsic pathway (PT) tends to lengthen first, and as levels drop further, the intrinsic pathway (PTT) also becomes prolonged. So in Rosie, this pattern most strongly signals exposure to an anticoagulant rodenticide.

Acetaminophen overdose mainly causes liver injury, which can secondarily affect clotting factor production but isn’t a direct vitamin K cycle inhibitor. Ethylene glycol toxicity causes metabolic acidosis and organ injury rather than a classic coagulation pattern. Diet-based vitamin K deficiency would more typically affect PT first, and isn’t about toxin exposure.