Free Codeine Concentration in Serum
This test measures the amount of free (unbound) codeine in your blood serum. Codeine is a pain reliever and cough suppressant that your body converts into morphine.
["Understanding your free codeine levels helps doctors assess how your body processes this medication."]
Key facts at a glance
- LOINC
- 97237-2
- Short code
- Codeine Free TissCo Ql Cfm
- Synonyms
- Codeine Free TissCo Ql Cfm
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- confirm
- 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’re taking codeine for pain, cough, or other conditions. It helps determine how much of the drug is actively working in your bloodstream, which can be important for managing side effects or adjusting doses.
How the Test Works
Blood is drawn from a vein, usually in your arm. The sample is then analyzed using a specialized laboratory method to measure free codeine levels, which are separated from other substances in your blood.
What to Expect Before the Test
No special preparation is needed, but let your doctor know if you’re taking other medications, have allergies, or are pregnant. Avoid eating or drinking anything for at least 8–12 hours before the test if instructed.
What to Expect During the Test
The test involves a quick blood draw, typically taking less than 5 minutes. You may feel slight discomfort, but it usually doesn’t cause pain. You can resume normal activities immediately afterward.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Free codeine levels help identify whether your dose is too high or too low. High levels may indicate poor metabolism, potential toxicity, or interactions with other medications. Low levels might suggest the drug isn’t working effectively, requiring dose adjustments. This is especially important for patients with liver or kidney issues, as these organs play a key role in breaking down codeine.
Short name
Free Codeine Level
Frequently asked questions
How long does it take to get results from this test?
Can I eat or drink anything before this test?
Is this test painful?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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