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Urine Fluoxetine-to-Creatinine Ratio

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

A urine test that measures the amount of fluoxetine relative to creatinine, which helps account for differences in urine concentration.

Quick summary

["This test can help determine whether fluoxetine is present in the urine."]

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

Key facts at a glance

LOINC
72813-9
Short code
FLUoxetine/Creat Ur
Synonyms
FLUoxetine/Creat Ur
Category
kidney
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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?

This test measures fluoxetine, a prescription antidepressant, in urine. The result may be compared with urine creatinine to account for how concentrated the urine sample is.

Why might I need this test?

It may be used to check for recent fluoxetine exposure or monitor medication use. Healthcare professionals may also use it when assessing adherence or possible drug interactions.

How is the test performed?

A urine sample is collected and analyzed in a laboratory. The laboratory measures fluoxetine and creatinine and may report their ratio.

How do I prepare for the test?

Follow your healthcare professional's instructions about medication timing and urine collection. Tell the laboratory about all medicines and supplements you take, because they can affect the result.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Urine Fluoxetine/Creatinine Ratio

Frequently asked questions

Does this test show how much fluoxetine I am taking?
Not by itself. Urine levels can reflect recent exposure and drug elimination, but they do not precisely identify the dose taken.
Why is creatinine included?
Creatinine helps account for variations in urine concentration. Dividing the fluoxetine measurement by creatinine can make urine results easier to compare.
Can another medicine cause a positive result?
A result is generally specific to exposure to fluoxetine, but medication history and laboratory methods should still be considered. Share all current and recent medicines with your healthcare professional.
  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