Lab Test

Acetaminophen Level

Tylenol, Acetaminophen Level, Serum, Anacin-3, Comtrex, Contact, Datril, Dristan, Excedrin, Nyquil, Sinutab, Tempera, Vanquish, APAP

Test Codes

Antrim #17244, EPIC: LAB5367, SOFT: ACETA



Specimen Collection Criteria

Collect: One plain Red-top tube. (Minimum Whole Blood: 1.0 mL)

Do not use Serum Separator Tubes.

Record the exact time of specimen collection on the tube or in the computer system.

Physician Office/Draw Specimen Preparation

Let specimens clot 30-60 minutes and refrigerate (2-8°C or 36-46°F) the collection tube within two hours of collection. (Minimum: 1.0 mL blood)

Preparation for Courier Transport

Transport: Collection tube, refrigerated (2-8°C or 36-46°F). (Minimum: 1.0 mL blood)

Rejection Criteria

  • Serum Separator (SST) tubes.
  • Severely lipemic or hemolyzed specimens.

In-Lab Processing

Let specimens clot 30-60 minutes. Centrifuge specimen to separate serum from cells. Deliver an aliquot of serum or the collection tube immediately to the appropriate testing station.


Specimen Stability for Testing:

Collection Tubes
Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 3 months

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days


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Taylor Chemistry Laboratory
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Wayne Chemistry Laboratory 


Sunday – Saturday, 24 hours a day.
STAT results available within 1 hour of receipt in the Laboratory.
Routine results available within 24 hours.

Reference Range

Therapeutic Range: 0-30 mcg/mL.
Critical Range: Greater than 50 mcg/mL.

Levels greater than 200 mcg/mL 4 hrs after ingestion; greater than 100 mcg/mL 8 hours after ingestion; and greater than 50 mcg/mL 12 hours after ingestion require evaluation according to the Rumack Nomogram.

Please consult the Rumack Nomogram for Toxicity. (1)

acetaminophen graphic

Test Methodology



Acetaminophen, when ingested in large amounts, or when taken chronically for long periods, may cause severe hepatic necrosis. Serum levels above those indicated in the Rumack nomogram indicate a high likelihood of toxicity and should prompt administration of N-acetycysteine, Mucomyst®.

Half Life in Blood: 3-6 hours.

Clinical Utility

Acetaminophen is an analgesic, antipyretic drug lacking in significant anti-inflammatory activity. This assay is used to monitor the therapeutic drug level and evaluate the toxicity of acetaminophen. Serum concentration and half-life are the only way to assess the degree of intoxication in the early stages since other liver function studies (bilirubin and liver function enzymes) will not show clinically significant increases until after tissue damage has occurred, at which point therapy is ineffective.


  1. Smilkstein, M.D., Martin J., Gary L. Knapp, M.S., Kenneth W. Kulig, M.D., and Barry H. Rumack, M.D. "Efficacy of Oral N-Acetylcysteine in the Treatement of Acetaminophen Overdose: Analysis of the National Multicenter Study (1976 to 1985)." The New England Journal of Medicine 319.24 (1988): 1557-562. Print.

CPT Codes

80329 (alternate: G0480).
LOINC:  3298-7, Last Dose Date  29742-4, Last Dose Time  29637-6


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