Test Code ACTMN Acetaminophen LAB43
Test Method
Particle Enhanced Turbidimetric Inhibition Immunoassay;
Beckman
Coulter
Performance
Monday through Sunday
Routine: Typically completed within 4 hours after arrival at
the
testing site.
Expedite: Typically completed within 2 hours after specimen
arrives at the testing site.
STAT: Typically completed within 1.5 hours after specimen
arrives at the testing site.
Useful For
Monitoring toxicity in overdose cases, Serum concentration
and
half-life are the only way to assess degree of intoxication in
early stages since other liver function studies (eg, bilirubin,
liver function enzymes) will not show clinically significant
increases until after tissue damage has occurred, at which
point
therapy is ineffective.
Specimen Requirement
0.5 mL lithium heparin serum or plasma is required.
CPT Code Information
Insurances following Medicare rules: G0480
80329 Analgesics, non-opioid; 1 or 2
Reference Values
Therapeutic: 10-30 mcg/mL
- Critical Value: > 40 mcg/mL
Post-ingestion Evaluation:
- Peak levels are reached between 30 and 60 minutes after
oral
dose. - Overdose cases: the specimen is drawn 4 hours after the time
of
suspected ingestion. - Elimination (half-life) Determination: In addition to
monitoring acetaminophen blood levels with respect to time
post-ingestion for evaluation of potential hepatoxicity,
elimination rate (half-life) of 2 to 3 hours is normal and not
associated with toxic damage to the liver. Acetaminophen levels as
low as 50 mcg/mL may be toxic when the half-life reaches 12 hours.
Half-life determination may be particularly useful in instances
where time of ingestion is not known and in following response to
therapy. Half-life can be determined by obtaining acetaminophen
levels at two accurately timed intervals at least 2 hours
apart.
LOINC Code Information
3298-7 Acetaminophen [Mass/Volume] In Serum Or Plasma
Additional Specimen Collection Information
Serum red-top tube or lithium heparin plasma green-top tube
is
acceptable. For overdose cases: the specimen is collected 4
hours
after the time of suspected ingestion. Serum and plasma gel
tubes
are NOT acceptable. Serum or plasma should be separated
from
contact with cells within 2 hours of collection. Refrigerate
specimen if unable to assay within 8 hours of collection.