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HelpTEST ID IODCU Iodine/Creatinine Ratio, Random, Urine
Reporting Name
Iodine/Creat Ratio, Random, USpecimen Type
UrineOrdering Guidance
Due to the significant variation in the rate of excretion 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 potentially interfere with inductively coupled plasma mass spectrometry-based metal 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 Metals Analysis Specimen Collection and Transport for complete instructions.
Specimen Minimum Volume
2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Refrigerated (preferred) | 28 days |
| Frozen | 28 days | |
| Ambient | 14 days |
Special Instructions
Method Name
IODC: Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
CRETR: Enzymatic Colorimetric Assay
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Reference Values
0-17 years: Not established
≥18 years: <584 mcg/g creatinine
Day(s) Performed
Monday through Friday
Report Available
2 to 4 daysSpecimen Retention Time
14 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
83789
82570
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 |
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.
Cautions
Administration of iodine-based contrast media and drugs containing iodine, such as amiodarone, will yield elevated results.
Method Description
Iodine:
The metal of interest is analyzed by inductively coupled plasma mass spectrometry.(Unpublished Mayo method)
Creatinine:
The enzymatic method is based on the determination of sarcosine from creatinine with the aid of creatininase, creatinase, and sarcosine oxidase. The liberated hydrogen peroxide is measured via a modified Trinder reaction using a colorimetric indicator. Optimization of the buffer system and the colorimetric indicator enables the creatinine concentration to be quantified both precisely and specifically.(Package insert: Creatinine plus ver 2. Roche Diagnostics; V15.0, 03/2019)