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Test Code U24 Iodine Iodine, 24 Hour, Urine

Reporting Name

Iodine, 24 Hr, U

Useful For

Monitoring iodine excretion rate as an index of daily iodine replacement therapy

 

Correlating total body iodine load with (131)I-uptake studies in assessing thyroid function


Specimen Required


Container/Tube: Plastic, 10-mL urine tube (T068) 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 in Special Instructions for complete instructions.

Additional Information:

1. 24-Hour volume is required.

2. See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens in Special Instructions for multiple collections.

3. 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, and all subsequent urine should be collected for the next 24 hours). The last void should be included in the collection.


Specimen Type

Urine

Specimen Minimum Volume

0.3 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Refrigerated (preferred) 146 days
  Ambient  146 days
  Frozen  146 days

Day(s) and Time(s) Performed

Monday, Tuesday, Wednesday, Friday; 5 p.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)

Method Description

This assay is performed on an inductively coupled plasma-mass spectrometer. Calibrating standards and blanks are diluted with an aqueous basic diluent containing internal standard(s). Quality control specimens and patient samples are diluted in an identical manner. In turn, all diluted blanks, calibrating standards, quality control specimens, and patient specimens are aspirated into a pneumatic nebulizer and the resulting aerosol directed to the hot plasma discharge by a flow of argon. In the annular plasma the aerosol is vaporized, atomized, then ionized. The ionized gases plus neutral species formed in the annular plasma space are aspirated from the plasma through an orifice into a quadrupole-mass spectrometer. The mass range from 1 amu to 263 amu is rapidly scanned multiple times and ion counts tabulated for each mass of interest. Instrument response is defined by the linear relationship of analyte concentration vs. ion count ratio (analyte ion count/internal standard ion count). Analyte concentrations are derived by reading the ion count ratio for each mass of interest and determining the concentration from the response line.(Unpublished Mayo method)

Reference Values

0-15 years: not established

≥16 years: 93-1,125 mcg/specimen

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

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
TIME5 Collection Duration 13362-9
VL23 Urine Volume 3167-4
3346 Iodine Concentration 26842-5

Reject Due To

Hemolysis

NA

Lipemia

NA

Icterus

NA

Other

NA

Urine Preservative Collection Options

 Ambient

Yes

Refrigerated

Preferred

Frozen

Yes

6N HCl

No

50% Acetic Acid

Yes

Na2CO3

No

Toluene

No

6N HNO3

No

Boric Acid

No

Thymol

No