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Serum Methadone Mass Concentration

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

This test measures the amount of methadone, a long-acting opioid medication, in your blood. It helps monitor your dose and ensure safe levels.

Quick summary

["This test checks your methadone blood levels to guide treatment and prevent overdose or withdrawal symptoms."]

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

Key facts at a glance

LOINC
34427-5
Short code
R-methadone SerPl-mCnc
Synonyms
R-methadone SerPl-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Matters

Methadone is used to manage opioid dependence or chronic pain. Your doctor may order this test to adjust your dose, confirm compliance, or detect toxicity. Levels can vary based on how your body processes the medication, your metabolism, and whether you’re taking other drugs.

How the Test Works

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where specialized equipment measures methadone’s concentration using a highly sensitive method called high-performance liquid chromatography (HPLC). This ensures accurate results even at very low levels.

What to Expect Before the Test

No special preparation is needed, but you may want to avoid eating or drinking for a few hours before the test if instructed by your provider. Wear comfortable clothing and bring any medications you’re currently taking to discuss with your doctor.

What to Expect After the Test

The blood draw typically takes a few minutes. You may feel slight discomfort, but it usually goes away quickly. You can resume normal activities immediately. If you experience dizziness or fainting, let your doctor know right away.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Methadone Level (Serum)

Frequently asked questions

Too much methadone can cause dangerous side effects like slowed breathing, confusion, or coma. Too little may not provide enough pain relief or prevent withdrawal symptoms. Your doctor uses these results to balance safety and effectiveness in your treatment plan.
This test helps ensure your methadone dose is appropriate for your needs and avoids risks like overdose or withdrawal. It’s especially important if you’re managing long-term opioid use or have liver/kidney issues that affect drug processing.
How often should I get this test?
Your doctor will determine the timing based on your treatment plan. Typically, it’s done every few weeks to monitor levels, especially if you’re adjusting your dose or have risk factors like substance use disorders or liver problems.
What if my results are outside the expected range?
If your methadone level is too high, your doctor may reduce your dose or switch to a different medication. If it’s too low, they may increase your dose or check for other factors (like drug interactions or poor absorption). Always discuss results with your healthcare provider.
  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