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HelpTest ID: UIOD Iodine, 24 Hour, Urine
Reporting Name
Iodine, 24 Hr, UUseful For
Assessing iodine toxicity or recent exposure in a 24-hour urine collection
Monitoring iodine excretion rate as index of replacement therapy
Clinical Information
Iodine is an essential element for thyroid hormone production. The measurement of urinary iodine is preferred for assessment of toxicity, recent exposure, and monitoring iodine excretion rate as an index of replacement therapy.
Interpretation
Measurement of urinary iodine excretion provides the best index of dietary iodine intake and deficiency is generally indicated when the concentrations are below 100 mcg/L.
World Healthcare Organization (WHO) Criteria for Assessing Iodine Status
Children older than 6 years old and adults
|
Median urinary iodine (mcg/L) |
Iodine intake |
Iodine status |
|
<20 |
Insufficient |
Severe deficiency |
|
20-49 |
Insufficient |
Moderate deficiency |
|
50-99 |
Insufficient |
Mild deficiency |
|
100-199 |
Adequate |
Adequate nutrition |
|
200-299 |
Above requirements |
May pose a slight risk of more than adequate |
|
>299 |
Excessive |
Risk of adverse health consequences |
Pregnant women
|
Median urinary iodine (mcg/L) |
Iodine intake |
|
<150 |
Insufficient |
|
150-249 |
Adequate |
|
250-499 |
Above requirements |
|
>499 |
Excessive |
Lactating women and children younger than 2 years old
|
Median urinary iodine (mcg/L) |
Iodine intake |
|
<100 |
Insufficient |
|
>99 |
Adequate |
Special Instructions
Report Available
1 to 4 daysDay(s) Performed
Tuesday, Friday
Clinical Reference
1. Rifai N, Chiu RWK, Young I, Burnham CAD, Wittwer CT, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier; 2023.
2. Knudsen N, Christiansen E, Brandt-Christensen M, et al. Age- and sex-adjusted iodine/creatinine ratio. A new standard in epidemiological surveys? Evaluation of three different estimates of iodine excretion based on casual urine samples and comparison to 24 h values. Eur J Clin Nutr. 2000;54(4):361-363
3. Liberman CS, Pino SC, Fang SL, et al. Circulating iodine concentrations during and after pregnancy. J Clin Endocrinol Metab. 1998;83(10):3545-3549
4. Pfeiffer CM, Sternberg MR, Schleicher RL, et al: CDC's Second National Report on Biochemical Indicators of Diet and Nutrition in the US Population is a valuable tool for researchers and policy makers. J Nutr. 2013;143(6):938S-947S
5. Leung AM, Braverman LE. Consequences of excess iodine. Nat Rev Endocrinol. 2014;10(3):136-142.
 doi:10.1038/nrendo.2013.251
6. U.S. Department of Health and Human Services, Agency for Toxic Substances and Disease Registry: Toxicological Profile for Iodine. HHS, 2004 Accessed June 29, 2023. Available at www.atsdr.cdc.gov/ToxProfiles/tp158.pdf
Method Name
Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
Specimen Type
UrineNecessary Information
24-Hour volume (in milliliters) is required.
Specimen Required
Patient Preparation:
1. High concentrations of gadolinium and iodine are known to interfere with most metal tests. If gadolinium- or iodine-containing contrast media has been administered, wait a minimum of 96 hours before starting collection.
2. If this test is used in conjunction with the (131)I uptake test, then specimen collection should begin immediately after the dose of (131)I is given (ie, the patient should void and discard urine just prior to the (131)I dose, and all subsequent urine should be collected for the next 24 hours). The last void should be included in the collection.
Supplies: Urine Tubes, 10 mL (T068)
Container/Tube: Plastic: 10-mL urine tube or clean, plastic aliquot container with no metal cap or glued insert
Specimen Volume: 10 mL
Collection Instructions:
1. Collect urine for 24 hours.
2. Refrigerate specimen within 4 hours of completion of 24-hour collection.
3. See Trace Metals Analysis Specimen Collection and Transport for complete instructions.
Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens for multiple collections.
Specimen Minimum Volume
0.3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 146 days | |
| Ambient | 146 days | ||
| Frozen | 146 days |
Reference Values
0-17 years: Not established
≥18 years: 75-851 mcg/24 hour
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
83789
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| UIOD | Iodine, 24 Hr, U | 2492-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 9549 | Iodine, 24 Hr, U | 2492-7 |
| 614369 | Iodine Concentration | 26842-5 |
| 614423 | Iodine Concentration Interpretation | 77202-0 |
| TIME5 | Collection Duration | 13362-9 |
| VL23 | Urine Volume | 3167-4 |
mml-endo-thyroid