Phentermine/Creatinine Ratio, Urine
A urine toxicology test that checks for phentermine, an appetite-suppressant medicine, and compares its amount with urine creatinine to account for urine concentration.
["This test can identify recent phentermine exposure, but results should be interpreted with timing, dose, and other clinical factors."]
Key facts at a glance
- LOINC
- 64134-0
- Short code
- Phentermine/Creat Ur
- Synonyms
- Phentermine/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 urine test measures phentermine, a prescription appetite-suppressant used for weight management. It also measures creatinine, a waste product used as a reference for urine concentration, so the phentermine result can be interpreted even when the urine is dilute or concentrated.
Why might I need this test?
A clinician or workplace program may order this test to check for recent phentermine use. It may be included when monitoring medication use, investigating drug exposure, or assessing whether a person is taking a weight-loss medicine as prescribed.
How is the test performed?
A urine sample is collected and analyzed in a laboratory. Screening methods may be used first, and any positive finding may be confirmed with a more specific laboratory method.
How do I prepare for the test?
Follow the collection instructions provided by the clinic or testing site and provide the urine sample in the specified container. Do not stop prescribed medication or deliberately change your fluid intake unless your healthcare professional instructs you to do so.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A detectable phentermine result generally indicates recent exposure to the medicine, although the exact timing cannot be determined from this test alone. An unexpectedly high result relative to urine creatinine may suggest a recent dose, concentrated urine, or medication use that differs from the prescribed plan. A positive result does not by itself prove misuse, toxicity, impaired driving, or another medical condition.
Short name
Urine phentermine test
Frequently asked questions
Does this test measure kidney function?
Can I use this test to tell exactly when I took phentermine?
What if I take phentermine exactly as prescribed?
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