Monitor therapeutic drug level, evaluate acetaminophen toxicity
Therapeutic range: 10-30 mcg/mL
Venipuncture should occur prior to Metamizole (Sulpyrine) administration due to the potential
for falsely elevated results.
N-acetylcysteine (NAC) levels above 200 mg/L will have a negative effect on results for acetaminophen. The level of interference is in direct proportion to the concentration of NAC present and can be significant.
- ACETAMINOPHEN LEVEL
STAT requests for this test will be performed on a STAT basis (supervisory staff approval is not required).
Collect specimen in an SST tube. Centrifuge, aliquot serum into a plastic vial and refrigerate.
Acetaminophen is rapidly absorbed from the gastrointestinal tract, with peak levels occurring 1-3 hours after ingestion. Serum levels drawn less than 4 hours after ingestion may not represent peak levels. The normal half-life of the drug is approximately 3 hours. A half-life of greater than 4 hours indicates impaired metabolism and potential for hepatic injury. Toxicity due to acetaminophen should be monitored by determining both serum concentration and rate of clearance (half-life). An elevated serum acetaminophen with a half life of greater than 4 hours indicates a high likelihood of hepatic injury. The hepatic toxicity of acetaminophen is related to the formation of one or more highly reactive metabolites in the liver. Orally administered N-acetylcysteine (Mucomyst) has been shown to provide protection against acetaminophen toxicity. The patient's condition should be monitored clinically for hepatotoxicity. Liver function tests may be indicated.