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Pentobarbital/Creatinine Ratio, Urine

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

A urine test that measures pentobarbital relative to creatinine, helping account for differences in urine concentration when evaluating barbiturate exposure.

Quick summary

["This test can help determine whether pentobarbital is present in the urine, but results must be interpreted with other clinical findings."]

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

Key facts at a glance

LOINC
64132-4
Short code
Pentobarb/Creat Ur
Synonyms
Pentobarb/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 the amount of pentobarbital, a barbiturate medicine, in urine and compares it with the amount of creatinine in the same sample. Creatinine is used as a marker of urine concentration.

Why might I need this test?

It may be used to evaluate suspected pentobarbital use, monitor medication exposure, or investigate possible drug overdose. A health care professional determines whether this test is appropriate based on the situation.

How is the test performed?

A urine sample is collected and analyzed by the laboratory, often using a method that can identify and quantify pentobarbital. The laboratory then calculates the amount of pentobarbital relative to creatinine.

How do I prepare for the test?

Follow the collection instructions provided by the laboratory or health care professional. If drug testing is for employment, legal, or medical monitoring purposes, ask whether there are specific instructions or restrictions.

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

Urine Pentobarbital-Creatinine Ratio

Frequently asked questions

Does this test show how much pentobarbital is in my blood?
No. This test uses urine and measures pentobarbital relative to creatinine. Blood pentobarbital testing is a separate test.
Why is creatinine included in the result?
Creatinine helps account for how concentrated or dilute the urine is. This makes comparisons between urine samples more useful.
Can this test prove that someone misused pentobarbital?
No. The result can show exposure, but it cannot by itself determine intent, dose, or timing of use. A health care professional must interpret it with the clinical context.
  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