The test for acetaminophen is used to measure the level of drug in the blood in order to establish a diagnosis of overdosage, to assess the risk of liver damage, and to help decide on the need for treatment. Prompt diagnosis and treatment are important for a positive outcome.

Since high levels of acetaminophen can be toxic to the liver, health practitioners may also order tests such as AST and ALT to detect liver damage. A PT may be used to detect impaired liver function. A health practitioner might also order serum salicylate levels or a urine drug screen for unconscious patients or those for whom there is a suspicion of ingestion of other substances. Other possible tests include blood gases, lactate level, and metabolic panel with creatinine. These are used to monitor severity of liver failure and, in cases of severe overdose, determine whether an overdose patient would benefit from liver transplantation.

The table below summarizes some results that may be seen:

Acetaminophen Level Result Interpretation
10-20 mcg/mL Therapeutic levels
Less than 150 mcg/mL 4 hours after ingestion Low risk of liver damage
Greater than 200 mcg/mL 4 hours after ingestionOr

Greater than 50 mcg/mL 12 hours after ingestion

Associated with toxicity and liver damage

The levels discussed above typically apply to a single ingestion of a toxic amount of the drug. They do not necessarily apply to cases in which the recommended amount of acetaminophen has been exceeded over a period of time (chronic overdose ingestion). However, a health practitioner may take acetaminophen levels into account along with clinical signs and symptoms and liver tests to determine the risk and/or presence of liver damage in chronic overdose cases.

  • Sample of blood serum
  • We perform the test daily