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Test ID ICRU Iodine/Creatinine Ratio, Random, Urine

Useful 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

Method Name

ICR: Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)

CDCR: Enzymatic Colorimetric Assay

Reporting Name

Iodine/Creat Ratio, Random, U

Specimen Type


Advisory 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

Reference Values

0-17 years: not established

≥ 18 years: <584 mcg/g creatinine

Day(s) and Time(s) Performed

Monday, Thursday; Continuously

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information



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

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.

Profile Information

Test ID Reporting Name Available Separately Always Performed
ICR Iodine/Creat Ratio, U No Yes
CDCR Creatinine Conc No Yes

NY State Approved