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N-Nortramadol/Creatinine Mass Ratio, Urine

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

A urine test that measures nortramadol, an active tramadol metabolite, relative to creatinine. The ratio helps account for urine dilution during monitoring.

Quick summary

["This test can help assess recent tramadol exposure, but the result must be interpreted with dose timing, symptoms, and other clinical findings."]

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

Key facts at a glance

LOINC
87760-5
Short code
N-nortramadol/Creat Ur Cfm
Synonyms
N-nortramadol/Creat Ur Cfm
Category
kidney
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
confirm
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?

Nortramadol is an active metabolite formed when the body breaks down tramadol, a prescription pain medicine. This urine test measures the amount of nortramadol relative to creatinine, a substance used to show how concentrated the urine is.

Why might I need this test?

A clinician may use this test to help assess recent tramadol exposure or monitor treatment. It may be ordered during pain management or when there is concern about medication use, unusual effects, or a need to confirm another test result.

How is the test performed?

A urine sample is collected and tested to determine the amounts of nortramadol and creatinine. The laboratory then calculates their ratio. Because urine drug screening tests can sometimes give misleading results, additional confirmatory testing may be needed.

How do I prepare for the test?

Follow the collection instructions provided by your clinician or laboratory. A random urine sample or a timed collection may be required, depending on the reason for testing. Do not drink extra water to dilute the urine, and tell the laboratory when you last took tramadol or any other medication.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Urine nortramadol-to-creatinine ratio

Frequently asked questions

What is nortramadol?
Nortramadol is an active metabolite of tramadol. It contributes to tramadol's pain-relieving effects and can also be associated with side effects.
Does this test show exactly how much tramadol I took?
No. It estimates recent exposure to tramadol, but urine levels vary with timing, fluid intake, dose, and metabolism. It cannot determine an exact dose on its own.
Can a urine nortramadol result prove medication misuse?
No. A result should not be used by itself to prove misuse because timing, test limitations, and other medications can affect it. A clinician should interpret it with the full 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 16, 2026. · Read our editorial policy