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HelpTest Code IODCU Iodine/Creatinine Ratio, Random, Urine
Ordering Guidance
Due to the significant variation in the rate of secretion over the course of a day, a 24-hour collection is preferred. For more information see UIOD / Iodine, 24 Hour, Urine.
Specimen Required
Patient Preparation: High concentrations of gadolinium and iodine are known to interfere with most metal tests. If either gadolinium- or iodine-containing contrast media has been administered, wait a minimum of 96 hours before starting collection.
Supplies: Urine Tubes, 10 mL (T068)
Collection Container/Tube: Clean, plastic urine collection container
Submission Container/Tube: Plastic, 10-mL urine tube or a clean, plastic aliquot container with no metal cap or glued insert
Specimen Volume: 3 mL
Collection Instructions:
1. Collect a random urine specimen.
2. See Metals Analysis Specimen Collection and Transport for complete instructions.
Useful For
Assessment of iodine toxicity or recent iodine exposure using a random urine collection
Monitoring iodine excretion rate as index of replacement therapy
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| IODC | Iodine/Creat Ratio, U | No | Yes |
| CRETR | Creatinine, Random, U | No | Yes |
Special Instructions
Method Name
IODC: Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
CRETR: Enzymatic Colorimetric Assay
Reporting Name
Iodine/Creat Ratio, Random, USpecimen Type
UrineSpecimen Minimum Volume
2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 30 days | |
| Frozen | 30 days | ||
| Ambient | 14 days |
Reference Values
0-17 years: Not established
≥18 years: <584 mcg/g creatinine
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. For deficiency, 10 repeat random urines are recommended.
World Healthcare Organization (WHO) Criteria for Assessing Iodine Status
Children older than 6 years 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
|
Median urinary iodine (mcg/L) |
Iodine intake |
|
<100 |
Insufficient |
|
>99 |
Adequate |
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, Nygaard B, Perrild H. 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, Braverman LE, Emerson CH. 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. 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
6. Leung AM, Braverman LE. Consequences of excess iodine. Nat Rev Endocrinol. 2014;10(3):136-142. doi:10.1038/nrendo.2013.251
7. Beckford K, Grimes CA, Margerison C, et al. A systematic review and meta-analysis of 24-h urinary output of children and adolescents: impact on the assessment of iodine status using urinary biomarkers. Eur J Nutr. 2020;59(7):3113-3131. doi:10.1007/s00394-019-02151-w
Day(s) Performed
Tuesday, Friday
Report Available
2 to 5 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
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
82570
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| IODCU | Iodine/Creat Ratio, Random, U | 55928-6 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| CRETR | Creatinine, Random, U | 2161-8 |
| 614424 | Iodine Concentration Interpretation | 77202-0 |
| 614370 | Iodine Concentration | 2495-0 |
| 610709 | Iodine/Creat Ratio, U | 55928-6 |