Norfluoxetine/Creatinine [Mass Ratio] in Urine
Measures the active metabolite of fluoxetine in urine relative to urine creatinine, which can help assess medication exposure while reducing the effect of urine dilution.
["This test can help determine how much fluoxetine-related medication is present in the body at the time of collection."]
Key facts at a glance
- LOINC
- 72812-1
- Short code
- Norfluoxetine/Creat Ur
- Synonyms
- Norfluoxetine/Creat Ur
- Category
- kidney
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 86430
- Specimen volume
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What is this test?
Norfluoxetine is the active metabolite of fluoxetine, a medicine used for depression and certain other conditions. This urine test measures norfluoxetine relative to creatinine, a substance used to help account for how concentrated the urine is.
Why might I need this test?
A clinician may order this test to check medication exposure, adherence, persistence, or possible effects of other medicines. It may also be used when there is concern about excessive drug effects or an unexpected treatment response.
How is the test performed?
A urine sample is analyzed in the laboratory to determine the amount of norfluoxetine and creatinine. The results are used to calculate a norfluoxetine-to-creatinine ratio.
How do I prepare for the test?
Follow the collection instructions and timing provided by your clinician or laboratory. Fasting is generally not required, but unusual fluid intake and the time since the last dose can affect urine results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A higher-than-expected result may reflect recent or substantial dosing, reduced drug clearance, or interactions with other medicines. A lower result may occur with missed doses, rapid metabolism, dilute urine, or a long interval after dosing. Results should be interpreted with the prescribed dose, collection time, symptoms, and other clinical findings.
Short name
Urine norfluoxetine
Frequently asked questions
Is this the same as a routine urine drug screen?
Why is creatinine included in the test?
What if my result is unexpectedly high or low?
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