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24-Hour Iodine Excretion Rate

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

This test measures how much iodine your body eliminates in urine over a 24-hour period. It helps assess thyroid function and iodine metabolism.

Quick summary

["This test helps check if your thyroid gland is using iodine properly or if there’s an iodine imbalance in your body."]

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

Key facts at a glance

LOINC
11220-1
Short code
Iodine Free 24h Ur-mRate
Synonyms
Iodine Free 24h Ur-mRate
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Ref low
20
Ref high
400
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82670
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

Why This Test Is Done

Your doctor may order this test if you have symptoms like fatigue, weight changes, or thyroid-related issues. It can also be used to monitor iodine levels in people with thyroid disorders or those taking iodine-containing medications.

What to Expect Before the Test

No special preparation is needed. You’ll collect all your urine for a full 24 hours, typically starting after midnight the night before the test and ending the same day. Store the urine in a clean container and bring it to your lab appointment.

How the Test Works

The test measures iodine concentration in your urine. The amount of iodine excreted reflects how your body processes iodine, which is important for thyroid hormone production.

Possible Results and Interpretation

Results are compared to a reference range, but exact values can vary by lab. Low iodine excretion may suggest thyroid dysfunction or iodine deficiency, while high levels could indicate overuse of iodine-containing supplements or certain medical conditions.

Reference range

Premenopausal: 20-400 pg/mL; Postmenopausal: <30 pg/mLN/A

Specimen: urine

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Iodine Urine Rate

Frequently asked questions

What causes low iodine excretion?
Low iodine excretion may be due to thyroid dysfunction (such as hypothyroidism), dietary iodine deficiency, or certain medications that affect iodine metabolism. It can also occur in people with kidney issues or those with iodine-blocking medications.
What causes high iodine excretion?
High iodine excretion can result from taking excessive iodine supplements, having certain thyroid disorders (like hyperthyroidism), or conditions that increase iodine absorption, such as some medications or dietary factors.
How often is this test repeated?
Your doctor may repeat this test if initial results are abnormal or if you have ongoing symptoms related to iodine metabolism. Follow-up testing depends on your medical history and treatment plan.
  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