Paracetamol
At a Glance
Why Get Tested?
In order to assess risk of liver damage after overdosage and to decide on the need for protective, antidotal therapy
When to Get Tested?
At least 4 hours after a single overdose, or as soon as possible if more then one overdose has been taken within the last 1 or 2 days
Sample Required?
A blood sample taken from a vein usually in an arm
The Test Sample
What is being tested?
The plasma paracetamol concentration is being measured.
How is the sample collected for testing?
Normally from a vein in the arm by use of a needle and syringe.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
The Test
How is it used?
The plasma paracetamol concentration is used to establish a diagnosis of paracetamol overdosage and to help decide on the need for treatment.
When is it requested?
Only when paracetamol overdosage is a possibility.
What does the test result mean?
The plasma paracetamol concentration at a known time point between 4 and 15 hours after a single overdose has been taken, indicates the likelihood of liver damage developing after 2 or 3 days. This test therefore helps the doctor decide on the need for antidotal treatment to minimise the risk of such damage occurring.
Is there anything else I should know?
Taking as few as 10-20 500 milligram paracetamol tablets at once can cause serious, possibly fatal liver damage 2-4 days afterwards unless antidotal treatment is given within 15 hours. It is likely that there will be no symptoms of poisoning for 24-36 hours after taking the paracetamol even if a potentially fatal dose has been ingested. If paracetamol has been taken above the recommended dose you should seek medical help as soon as possible.
Common Questions
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Article Sources
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
