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Methadone Concentration (Serum or Plasma)

Published: August 9, 2026Updated: August 17, 2026

This test measures the amount of methadone, a long-acting opioid medication, in your blood. It helps doctors monitor your dose and ensure it’s working safely.

Quick summary

["Methadone levels help adjust your treatment to manage withdrawal symptoms or pain effectively."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
6902-1
Short code
Deprecated Methadone Gast Ql
Synonyms
Deprecated Methadone Gast Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84484
SNOMED
302774002
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 Is This Test Done?

Your doctor may order this test if you’re on methadone therapy to check your blood levels. This helps prevent overdose risks or ensure the medication is effective for managing symptoms like cravings or pain.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm or vein for a blood draw. It usually takes a few minutes, and you may feel a brief pinch. If you’re on a maintenance dose, your levels may be checked regularly.

What the Results Mean

Results show how much methadone is in your blood at the time of testing. They help your healthcare provider adjust your dose if needed, but they don’t replace medical judgment. Always discuss results with your doctor.

Common Reasons for Testing

Doctors may test methadone levels to confirm your dose is therapeutic, check for toxicity (e.g., if you’ve missed doses or taken extra), or monitor long-term use. It’s also used in detox programs to manage withdrawal safely.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Methadone Level

Frequently asked questions

How often should I get this test?
Your doctor will determine the frequency based on your treatment plan, dose, and medical history. For example, maintenance patients might need testing every few weeks, while those in detox may have more frequent checks.
What if my methadone level is too high or too low?
If levels are too high, it could indicate overdose risk or improper dosing. If too low, your symptoms (e.g., cravings, pain) may not be controlled. Your doctor will adjust your dose or explore other treatments if needed.
Does this test affect my medication?
No, this test is a diagnostic tool only. It doesn’t change your medication unless your doctor recommends it based on the results.
  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 17, 2026. · Read our editorial policy