24-Hour Urinary Diphenhydramine (Hydroxyzine) Excretion Rate
This test measures how much diphenhydramine (a medication used to treat allergies or anxiety) appears in your urine over a full day.
["This test helps assess how well your body processes certain allergy/anxiety medications."]
Key facts at a glance
- LOINC
- 3575-8
- Short code
- Dipipanone 24h Ur-mRate
- Synonyms
- Dipipanone 24h Ur-mRate
- Category
- chemistry
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 20
- Ref high
- 400
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82670
- 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
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you’re taking diphenhydramine and want to check how your kidneys are handling it. It could also be used in research or specialized clinical settings to evaluate drug metabolism in specific conditions.
What to Expect Before the Test
No special preparation is needed. You’ll provide a 24-hour urine sample collected in a container, starting after you urinate first thing in the morning and continuing until you urinate again the next morning. You’ll keep a record of all urine output.
How the Test Works
Your urine is tested for the presence of diphenhydramine. The test measures the amount of medication excreted over 24 hours, which helps determine how your body processes and removes it from your system.
What the Results Mean
Results are typically reported as the amount of diphenhydramine excreted in micrograms (mcg) per 24 hours. Higher than expected amounts might suggest issues with drug metabolism or kidney function, while lower amounts could indicate the medication isn’t being processed as expected.
Reference range
Premenopausal: 20-400 pg/mL; Postmenopausal: <30 pg/mLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
What does this test measure?
What are the typical reference ranges?
Can I drink alcohol before this test?
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