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Serum Methadone Concentration (Mass Concentration)

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

This test measures the amount of methadone in your blood serum. Methadone is a medication used to manage chronic pain or opioid dependence.

Quick summary

["Knowing your methadone level helps doctors adjust your dose for safety and effectiveness."]

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

Key facts at a glance

LOINC
48365-1
Short code
R-methadone SerPl-sCnc
Synonyms
R-methadone SerPl-sCnc
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

Your doctor may order this test to ensure your methadone dose is working as intended. It helps prevent overdose risks by monitoring your blood levels, especially if you’re on long-term treatment or adjusting your medication.

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. Tell your healthcare provider if you’re pregnant, have bleeding issues, or take blood thinners.

What the Results Mean

Results are typically reported in micrograms per milliliter (µg/mL). While reference ranges vary by lab and clinical context, your doctor will interpret the result based on your medical history and treatment goals.

Common Reasons for Testing

Doctors may test methadone levels to check for toxicity (too much drug), ensure proper dosing, or verify compliance with treatment plans, particularly in patients on opioid substitution therapy.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Methadone Level

Frequently asked questions

What causes false or inaccurate results?
False results can occur if you haven’t fasted (for some tests), have recent blood transfusions, or are taking certain medications that interact with methadone. Always follow your lab’s specific instructions for accuracy.
How long does it take to get results?
Results are usually available within 1–3 business days, depending on your lab’s processing time. Your doctor will contact you once they have the results.
Can I eat or drink before this test?
Most labs do not require fasting for this test, but confirm with your healthcare provider or lab technician before your appointment.
  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