Test library
Iodine Excretion Test
The 24-Hour Iodine Urine Test measures how much iodine is excreted in urine over a full day. It is used to assess iodine status and, in some cases, to evaluate conditions that cause excessive iodine loss.
Order Iodine Urine Test, 24-Hour
Order online and visit a local collection site, or choose an at-home kit where available. No referral and no insurance required.
Order Iodine Urine Test, 24-Hour- Typical turnaround
- 1-3 business days
- Starting price
- From $119
- Results
- Confidential, online
Quick answer
The 24-Hour Iodine Urine Test measures the amount of iodine passed in urine over a complete day. Iodine is needed to make thyroid hormones, and urine is the main route by which the body removes excess iodine. A full-day collection gives a broader picture of intake and excretion than a single spot sample, and the test is often used when iodine status or unusual iodine loss needs to be assessed.
What this test measures
Iodine is a mineral the thyroid gland uses to produce its hormones. The body does not make iodine, so it must come from food, iodized salt, and supplements. Most excess iodine leaves the body through the urine, which makes urine testing a practical way to estimate iodine status.
For a 24-hour collection, a person discards the first morning urine, then collects every urine sample for the next 24 hours, including the first morning sample of the following day. The volume is measured and a portion is sent to the laboratory, where iodine concentration is determined. The total amount excreted over the day is then calculated.
Results are usually reported as micrograms of iodine per 24 hours or as micrograms per liter along with total volume. Very low excretion can suggest insufficient iodine intake, while very high excretion can reflect excess intake or increased losses. Results are interpreted alongside diet, medications, and thyroid function tests when relevant.
- 24-hour urine volume
- Urine iodine concentration
- Total 24-hour iodine excretion
- Urinary iodine reported in micrograms per liter
- Creatinine level used to verify collection completeness
- Dietary iodine context when evaluated
Why people order this test
- Assess iodine status when dietary intake is uncertain
- Evaluate unusually high or low iodine loss
- Support thyroid-related clinical evaluation
- Monitor iodine excretion over time
- Add information when diet or supplements raise concern
- Investigate iodine status before or during pregnancy planning
How to prepare
A 24-hour urine collection is required. Discard the first morning urine on the collection day, then collect all urine for the next 24 hours, including the first morning sample the following day. Keep the container refrigerated if instructed, and follow the laboratory's written collection instructions.
Understanding your results
Results are usually available within two to four business days after the sample arrives. The report includes the collected volume and the total iodine excreted. A qualified healthcare provider should interpret the values with diet, medications, and thyroid testing.
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Frequently Asked Questions
What is a 24-hour iodine urine test?
It is a test that measures the total amount of iodine excreted in urine over a full day. The result reflects recent iodine intake and how much the body is removing.
How do I collect the sample?
Discard the first morning urine, then collect all urine for the next 24 hours, including the first sample the following morning. Follow the laboratory's instructions for storage and delivery.
What do the results mean?
Low excretion can suggest insufficient iodine intake, while high excretion can reflect excess intake or increased losses. A healthcare provider interprets the value with diet and thyroid testing.
Do I need to change my diet before the test?
Usually no special diet is required, but follow any instructions from the laboratory. If you take iodine-containing supplements or medications, mention them to the testing provider.
Can a spot urine test be used instead?
Spot urine iodine tests are sometimes used for screening, but a 24-hour collection gives a more complete measure of daily excretion and is preferred in many clinical situations.
Ready to get tested?
Order online and visit a collection site near you, or choose a mail-in kit. No referral and no insurance required.
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