Acetaminophen overdose treatment when acetaminophen levels are not available

The Manitoba Poison Centre has become aware that several hospitals have been unable to secure enough reagents/cartridges to be able to process acetaminophen concentrations. Acetaminophen levels are now “send outs” in these communities with a turnaround time of 3-5 days.

This may influence care and prompt us to change our recommendations as to whom to treat & when to stop.
Should a health care facility (HCF) be unable to process an acetaminophen level in a timely fashion on site, an accurate history of the ingestion is paramount. IF the history of ingestion is such that the patient could have taken a toxic dose (the amount available to the patient was > 10g or 200 mg/kg), then empiric treatment with n-acetylcysteine (NAC) should be started. The usual loading dose over 4 hours, followed by typical dosing maintenance should be recommended. To be conservative, these patients should receive a total of 24 hours of NAC infusion. IF the facility can do other labs, stopping NAC at the end of 24 hours will require that

1) the AST OR ALT is under 100 IU,
2) the patient is not acidemic & well, and
3) the INR <= 2.0.
We would still recommend that the 4 hour acetaminophen level be sent out, and an acetaminophen level at the end of the 24 hour infusion. The HCF should be able to contact that patient (with a telephone number) once levels are back if unexpected results are reported.
Margaret Thompson, MD
Medical Director, Ontario & Manitoba Poison Centre
(serving the Health Care providers in Nunavut)