Approach Considerations
Obtain the following tests in patients with possible rodenticide poisoning:
- Glucose fingerstick - In every patient with altered mental status
- Electrolytes, serum glucose level, and ketones - In patients suspected of exposure to PNU
- Pregnancy tests - In women of childbearing age
- Serum acetaminophen level - In every intentional exposure
- Complete blood count (CBC) - In patients with evidence of bleeding or hemolysis
- Creatine phosphokinase (CPK) and lactic acid - In patients suspected of exposure to strychnine (eg, "conscious seizures")
Measure PT and aPTT if the ingested substance is an anticoagulant. Possibly consider bleeding time and platelet count measurements in patients with evidence of bleeding. Requesting quantitative coagulation factors may be helpful, and these may be available far before actual analysis for suspect anticoagulant levels. Initial elevated PT and aPTT may suggest the possibility of chronic exposure.
Coagulation studies are expected to be normal in acute exposures to anticoagulants. These patients may require an international normalized ratio (INR) check on a daily basis for a couple days to rule out or confirm toxicity.
Because the availability of RBC cholinesterase is so poor, do not depend on supporting laboratory evidence when an exposure to an organophosphate-containing substance is suspected.
Laboratory verification of the anticoagulant rodenticides (eg, brodifacoum, difenacoum) is available; however, the result takes several days and is not necessary to guide therapy. Serial levels might only be helpful to estimate the drug half-life and duration of required therapy. In addition, blood tests for arsenic, thallium, mercury, and lead may be useful but are usually considerably time consuming.
Abdominal plain film radiography
If a metal rodenticide (eg, thallium, arsenic, barium) is considered, obtaining an abdominal plain film radiograph may be helpful, because these metals are radio-opaque.
Consultations
Consult with the regional poison control center or a medical toxicologist for additional information and patient care recommendations.
Obtain a psychiatric evaluation if the ingestion was intentional. Consult a hematologist or a medical toxicologist for long-term follow-up if a long-acting anticoagulant (eg, brodifacoum) was ingested.
Monitoring
Patients who ingest anticoagulant rodenticides and are discharged when their clotting studies are found to be normal may have delayed symptom onset and may continue to ingest the rodenticide once they are discharged. In these cases, the treating physician is responsible for proving that any sequela is not the result of a missed opportunity to treat. As previously stated, consult a hematologist or a medical toxicologist for long-term follow-up if a long-acting anticoagulant (eg, brodifacoum) was ingested.
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