Iodine Urine Test, 24-Hour
Below is a plain-language overview of the iodine urine test, 24-hour. The 24-hour iodine urine test measures how much iodine leaves your body in urine collected over a full day. It is usually ordered to check iodine status, since iodine is needed for thyroid hormone production. It may be used when a diet low or high in iodine is suspected, or when thyroid-related concerns are being evaluated.
- Sample type
- urine
- Category
- General Wellness
- Turnaround
- 1-3 business days
- Price
- $119
- Referral
- Not required
The 24-hour iodine urine test measures how much iodine leaves your body in urine collected over a full day. It is usually ordered to check iodine status, since iodine is needed for thyroid hormone production. It may be used when a diet low or high in iodine is suspected, or when thyroid-related concerns are being evaluated.
What it measures
- Iodine concentration — The amount of iodine in the urine sample, usually reported as micrograms per liter (mcg/L).
- 24-hour iodine excretion — The total iodine passed in urine over the collection period, often reported in micrograms per 24 hours.
- Urine volume — The total amount of urine collected, needed to calculate total iodine output.
- Creatinine (sometimes included) — A substance used to help check whether the 24-hour collection was complete.
Who it is for
A clinician may order this test when evaluating iodine status, thyroid symptoms, or the effect of diet or supplements. It is not a routine screening test for most adults.
Preparation
No fasting is usually required. You will be given a container and instructions to collect all urine for 24 hours, often starting after discarding the first morning sample and ending with the first sample the next morning.
Results and what they mean
Results are reported as iodine amounts in the urine and are interpreted alongside your diet, supplements, and clinical history. A clinician decides what the numbers mean for you; reference ranges vary by lab. This is general information, not medical advice.
How to order this test
- Choose the test and place a confidential order online.
- Select a certified collection site and pick a time that suits you.
- Have your specimen collected — most draws take only a few minutes.
- Review results in a secure portal, typically within 1–3 days.
Preparation, hours, and pricing vary by site; confirm details directly with the lab before your visit.
Availability by state
Direct-access online ordering for the iodine urine test, 24-hour is available in most states. It is currently unavailable in 6 states:
Everywhere else you can order confidentially and collect your sample at a certified site. Browse by state →
Frequently asked questions
Do I need to stop eating iodine-rich foods before the test?
Follow your clinician's instructions. Some providers ask you to avoid kelp, seaweed, iodized salt, and iodine supplements before collection, while others do not.
What happens if I miss part of the 24-hour collection?
Tell the lab or your clinician. An incomplete collection can make the results hard to interpret, and the test may need to be repeated.
How should I store the urine container?
Keep it cool, as directed by the lab. Many labs ask you to refrigerate it during the collection period and bring it in promptly when finished.
Can I drink water during the collection?
Yes, normal fluid intake is usually fine unless your clinician gives different instructions. Staying hydrated helps you produce enough urine for the test.