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Zolpidem Phenyl-4-Carboxylate/Creatinine Ratio, Urine

Published: August 9, 2026Updated: August 17, 2026

A urine test that measures a zolpidem metabolite relative to creatinine. It can help identify recent zolpidem exposure while accounting for differences in urine concentration.

Quick summary

["A detectable result can indicate recent exposure to zolpidem, but the result alone does not show when it was taken or whether a person is currently impaired."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
72769-3
Short code
Zolpidem phenyl-4-carb/Creat Ur
Synonyms
Zolpidem phenyl-4-carb/Creat Ur
Category
kidney
Sample
urine
Container
Sterile urine container
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85041
SNOMED
900000000000003001
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 zolpidem phenyl-4-carboxylate, a metabolite formed when the body breaks down zolpidem. The result may be compared with urine creatinine to help account for how concentrated or dilute the urine sample is.

Why might I need this test?

A clinician may order this test to check for recent zolpidem exposure, monitor use of prescribed zolpidem, or evaluate suspected drug misuse. It may also be used in certain occupational, legal, or substance-use assessments.

How is the test performed?

A urine sample is collected and analyzed in the laboratory for the zolpidem metabolite and creatinine. The results are reported as a ratio, and the laboratory may also provide a qualitative interpretation.

How do I prepare for the test?

No fasting is usually required. Follow the collection instructions and timing provided by the healthcare professional or laboratory, especially if the test is intended to monitor prescribed medication use.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: urine

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Zolpidem urine metabolite test

Frequently asked questions

Does this test show that zolpidem is causing sedation right now?
No. This is a urine exposure test and does not directly measure your current level of impairment or sedation. Other information is needed to assess effects after taking zolpidem.
Why is the result compared with creatinine?
Urine concentration can vary with hydration and fluid intake. Comparing the metabolite with creatinine helps adjust the result for differences in urine concentration.
Can I take my usual zolpidem before the test?
Only do so if the prescribing clinician or laboratory instructions say it is acceptable. Taking zolpidem before collection can produce a positive result, so follow the specific instructions for your test.
  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 17, 2026. · Read our editorial policy