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Fluoride/Creatinine Ratio, Urine — Turbidimetry

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

Measures urine fluoride relative to urine creatinine, helping account for urine concentration and assess fluoride exposure.

Quick summary

["This test can help evaluate fluoride exposure while adjusting for how concentrated the urine sample is."]

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

Key facts at a glance

LOINC
110445-4
Short code
Fluoride/Creat Msmt Ur
Synonyms
Fluoride/Creat Msmt 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 test measures the amount of fluoride in urine compared with the amount of creatinine in the same sample. Creatinine is used as a reference to help account for differences in urine concentration.

Why might I need this test?

It may be used to assess recent fluoride exposure from sources such as drinking water, fluoride supplements, toothpaste, or other environmental sources. It is also commonly used when monitoring people who may be at risk of excessive or insufficient fluoride intake.

How is the test performed?

A urine sample is collected and tested using a turbidimetric laboratory method. The laboratory reports the amount of fluoride relative to the amount of creatinine in that sample.

How do I prepare for the test?

Follow your clinician's or laboratory's instructions for collecting urine, including whether a first-morning or timed collection is required. Fasting is generally not necessary, and you should not change prescribed fluoride supplements unless instructed to do so.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Urine fluoride/creatinine ratio

Frequently asked questions

Does this test show how much fluoride I have absorbed?
It provides an estimate of recent fluoride exposure by measuring fluoride excreted in urine. It is not a direct measure of the total fluoride stored in the body.
Why is creatinine included in the result?
Urine concentration can change from one sample to another. Comparing fluoride with creatinine helps account for urine dilution and makes results easier to interpret.
Do I need to stop using fluoride toothpaste or supplements before the test?
Usually, you should continue your normal routine unless your clinician gives different instructions. If you use prescription fluoride supplements, tell the laboratory and your clinician so the result can be interpreted appropriately.
  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