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Acetaminophen (ACETR)

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EPIC Test Name

ACETAMINOPHEN

EPIC Code

LAB2547

Specimen Requirements

plasma
Minimum Volume:0.5 mL
Collection:Collect using standard laboratory procedures
Transport:Room Temperature ASAP
Stability:Room Temperature: 24 hours capped
Refrigerated: 7 days capped at 2-8 degrees C
Frozen: 6 months capped at -15 to 125 degrees C
Container:LIT-GRN
Rejection Causes:Insufficent Sample Volume
Notes:If time of ingestion is unknown, 2 specimens should be drawn 4 hours apart. Normally, by the time the second specimen is taken, the body has started to eliminate the drug and the second level should be lower than the first.

Methods

Colorimetric Assay

Turnaround Time

SpecimenTurnaround TimeFrequency
plasmaStat: 90 minutes Routine: 4 hours24/7

Reference Ranges

Colorimetric Assay
UnitCritical ValuesTherapeutic Levels
ug/mL>50.0 ug/mL10.0-30.0 ug/mL

Clinical Indications

Acetaminophen, commonly known as Tylenol and also are present in many common over-the-counter brand named drugs of Actifed, Anacin, Contac, Dristan, Excedrin, Nyquil, Sinutab, Vanquish, and many others) is an analgesic, antipyretic drug lacking significant anti-inflammatory activity. It is mainly metabolized by the liver with a half-life of ~ 1-3 hours. At therapeutic doses to patients with normal liver function, acetaminophen (~90%) is metabolized into nontoxic glucuronide or sulfate conjugates, which are subsequently eliminated via kidney. Hepatic glutathione involves in the detoxification process. In overdosed patients, hepatic glutathione is consumed and the toxic metabolite (postulated metabolite: N-acetylbenzoquinoneimine, NAPQI) reacts with cellular proteins resulting in hepatotoxicity, characterized by centrilobular necrosis and possible death if untreated. N-acetylcysteine as a substitute of glutathione can be used as an antidote.

Performed

Lab
Chemistry - Community
Chemistry - Downtown

Interpretative Information

For patient with acetaminophen intoxication, the initial symptoms can be absent or relatively mild and nonspecific (nausea, vomiting, and abdominal discomfort). Impending hepatic necrosis typically begins 24 to 36 hours after toxic ingestion and becomes most severe by 72 to 96 hours. Therefore, repeated test every 4 to 6 hours until returning to recovery is recommended. Serum concentration, half-life and Rumack-matthew nomogram can be used to assess the degree of intoxication in early stages when other liver function indicators, such as bilirubin and liver function enzymes, may not be significantly increased until after the liver damage has occurred, at which point therapy is ineffective.
For therapeutic usage, a blood level of acetaminophen fall within the range of 10 to 20 mcg/mL.

CPT

82003

LOINC

3298-7

References

1. Yu HE, Magnani B. Acetaminophen and salicylate. In The Clinical Toxicology Laboratory – contemporary practice of poisoning evaluation. ed. by Tai Kwong, etc., 2nd ed. Page 189-202.
2. Perry H, Shannon MW: Acetaminophen. LM Haddad MW Shannon JF Winchester Clinical management of poisoning and drug overdose. 3rd ed 1998 WB Saunders Philadelphia, PA 664-674

Contact Information

Chemistry - Downtown: (315)464-4460
Chemistry - Community: (315)492-5531
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