Rodenticide Toxicity Workup

Updated: Dec 29, 2015
  • Author: Derrick Lung, MD, MPH; Chief Editor: Asim Tarabar, MD  more...
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Workup

Approach Considerations

Obtain the following tests in patients with possible rodenticide poisoning:

  • Glucose (point-of-care) - In every patient with altered mental status
  • Electrolytes, serum glucose level, and ketones – Profound abnormalities may suggest exposure to uncommon rodenticides such as barium, cholecalciferol, or 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

Measure prothrombin time (PT), international normalized ratio (INR), and activated partial thromboplastin time (aPTT) if the ingested substance is an anticoagulant. Possibly consider bleeding time and platelet count measurements in patients with evidence of bleeding. If available, measurement of quantitative coagulation factors may be helpful, and these may be available far before actual analysis for suspect anticoagulant levels. Coagulation studies are expected to be normal in acute exposures to anticoagulants. These patients may require serial testing for 2 days to rule out or confirm toxicity. Abnormal measurements on initial testing suggest the possibility of long-term exposure.

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 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 sequelae are 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 was ingested.