Skip to content

Iodine-to-Creatinine Ratio, Urine

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

A urine test that measures iodine relative to creatinine, helping assess iodine intake and iodine status, particularly in children or people with irregular urine output.

Quick summary

["This test estimates iodine exposure by comparing urinary iodine with urinary creatinine."]

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

Key facts at a glance

LOINC
55928-6
Short code
Iodine/Creat Ur
Synonyms
Iodine/Creat 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?

The iodine-to-creatinine ratio measures the amount of iodine in a urine sample compared with the amount of creatinine. Creatinine is a waste product whose level helps account for how concentrated the urine is.

Why might I need this test?

This test may be used to assess recent iodine intake and help identify possible iodine deficiency or excessive iodine exposure. It is often used for nutritional surveillance, particularly in children, and may be paired with thyroid tests when iodine-related thyroid problems are suspected.

How is the test performed?

A urine sample is collected and tested for iodine and creatinine. The laboratory calculates the iodine-to-creatinine ratio. Results can vary from day to day with diet and iodine supplement use, so a clinician may consider several results together.

How do I prepare for the test?

Follow the laboratory's instructions about the type and timing of urine collection. Tell your clinician about iodine supplements, thyroid medicines, and any recent changes in your diet, because these can affect the result.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Urinary Iodine-to-Creatinine Ratio

Frequently asked questions

Does this test show whether my thyroid is working properly?
Not by itself. It estimates iodine exposure, while thyroid function is assessed with tests such as TSH and free T4.
Why is creatinine included in the test?
Creatinine helps account for urine concentration. Dividing iodine by creatinine allows results from samples with different concentrations to be compared more easily.
Can iodine supplements affect my result?
Yes. Supplements, iodine-containing medicines, and high-iodine foods can increase urinary iodine, so report their use to your clinician.
  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