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Paracetamol (Acetaminophen) Immunoassay, Quantitative, Plasma

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of acetaminophen (paracetamol), a common pain reliever and fever reducer, in your blood plasma.

Quick summary

["Knowing your acetaminophen level helps monitor safe dosing and detect potential overdose."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
73546-4
Short code
APAP ind plt IgG SerPl Ql FC
Synonyms
APAP ind plt IgG SerPl Ql FC
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
82784
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your healthcare provider may order this test if you’ve taken acetaminophen for pain or fever, especially if you’ve had large doses or taken it for an extended period. It may also be used to assess liver function or rule out poisoning from acetaminophen overdose.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or vein to draw a blood sample. If you’re on blood thinners, let your provider know before the test.

What the Test Results Mean

Results are compared to a general reference range, but exact values can vary by lab. High levels may indicate overdose or liver strain, while low levels suggest insufficient exposure. Your provider will interpret results in the context of your medical history and symptoms.

Common Causes of Abnormal Results

Elevated acetaminophen levels are most commonly linked to intentional or accidental overdose, chronic excessive use, or liver disease. Very low levels may occur if you’ve recently stopped taking acetaminophen or have poor absorption.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

APAP Level (Plasma)

Frequently asked questions

How long does it take to get test results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your provider will contact you once results are ready.
Can I take acetaminophen before or after this test?
Avoid taking acetaminophen for at least 24 hours before your test to get an accurate measurement. If you’ve recently taken it, your provider may ask for a different sample time.
Does this test detect other substances besides acetaminophen?
No, this test specifically measures acetaminophen levels. If you suspect other drug ingestion, additional tests may be needed.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy