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HelpTest ID ICRU Iodine/Creatinine Ratio, Random, Urine
Reporting Name
Iodine/Creat Ratio, Random, UUseful For
Assessment of iodine toxicity or recent exposure when a 24-hour urine cannot be collected
Monitoring iodine excretion rate as index of replacement therapy when a 24-hour urine cannot be collected
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| ICR | Iodine/Creat Ratio, U | No | Yes |
| CDCR | Creatinine Conc | No | Yes |
Specimen Type
UrineAdvisory Information
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 metals tests. If either gadolinium- or iodine-containing contrast media has been administered, a specimen should not be collected for 96 hours.
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 Trace Metals Analysis Specimen Collection and Transport in Special Instructions for complete instructions.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 30 days | |
| Ambient | 30 days | ||
| Frozen | 30 days |
Special Instructions
Reference Values
0-17 years: not established
≥ 18 years: <584 mcg/g creatinine
Day(s) and Time(s) Performed
Monday, Thursday; Continuously
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.CPT Code Information
83789
82570
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| ICRU | Iodine/Creat Ratio, Random, U | 55928-6 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| CDCR | Creatinine Conc | 2161-8 |
| 32874 | Iodine/Creat Ratio, U | 55928-6 |
Clinical Information
Iodine is an essential element for thyroid hormone production.
The measurement of urinary iodine serves as an index of adequate dietary iodine intake.
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.
Clinical Reference
1. Nader R, Horwath AR, Wittwer CT: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Sixth edition. St. Louis. Elsevier 2017
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;54:361-363
3. Liberman CS, Pino SC, Fang SL, et al: Circulating iodine concentrations during and after pregnancy. J Clin Endocrinol Metab 1998;83:3545-3549
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
Analytic Time
1 dayMethod Name
ICR: Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)
CDCR: Enzymatic Colorimetric Assay