Test Overview
Test Methodology


Test Usage

Monitor therapeutic drug level, evaluate acetaminophen toxicity

Reference Range *

Therapeutic range: 10-30 mcg/mL

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Limitations

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.

Test Details
Days Set Up
Daily, 24 hours
Analytic Time

1 hour

Soft Order Code
MiChart Code
Acetaminophen Level
  • Datril
  • Distalgesic
  • Paracetamol
  • Tylenol
Chemical Pathology
STAT Availability

STAT requests for this test will be performed on a STAT basis (supervisory staff approval is not required).

Specimen Requirements
Collection Instructions

Collect specimen in an SST tube. Centrifuge, aliquot serum into a plastic vial and refrigerate.

Alternate Specimen
Red top or Green top (lithium heparin) tube. [rev 10/22]
Normal Volume
1 mL serum
Minimum Volume
0.25 mL serum
Additional Information

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.

CPT Code
Fee Code