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Iodine, 24-Hour Urine

Urine Iodine

Test Codes

EPIC: LAB1231707, Beaker: XIODU, Mayo: UIOD

Department

Send Outs

Instructions

• Please refer to the Specimen Collection Manual for instructions on 24-Hour Urine Collection:
  • Urine 24-Hour Collection - Inpatient
  • Urine 24-Hour Collection - Outpatient
  • Urine 24-Hour Collection - Outreach
• If this test is used in conjunction with the ¹³¹I uptake test, then specimen collection should begin immediately after the dose of ¹³¹I is given (i.e., the patient should void and discard urine just prior to the ¹³¹I, and all subsequent urine should be collected for the next 24 hours). The last void should be included in the collection.

Specimen Collection Criteria

Collect: 24-hour urine sample with no preservative.

• Keep 24-hour urine specimen iced or refrigerated during collection.
• Include start and end dates and times for the collection period on the specimen container.

Urine Preservative Options
No Preservative	6N Hydrochloric Acid	Boric Acid (10g)	Sodium Carbonate	50% Acetic Acid
PREFERRED	Unacceptable	Unacceptable	Unacceptable	Acceptable

Physician Office/Draw Specimen Preparation

Maintain specimens refrigerated (2-8°C or 36-46°F) prior to transport.

Preparation for Courier Transport

Transport: Entire 24-hour urine collection, refrigerated (2-8°C or 36-46°F).

Rejection Criteria

• Random urine specimens.
• Specimens not collected and processed as indicated.

In-Lab Processing

Measure total volume of 24-hour urine specimen. Record total volume and collection start and end dates and times in the LIS system. Aliquot 10.0 mL from the well-mixed 24-hour urine collection. (Minimum: 0.3 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 146 days
Refrigerated (2-8°C or 36-46°F): 146  days
Frozen (-20°C/-4°F or below): 146 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Mayo Medical Laboratories, Rochester, MN.

Performed

Monday, Wednesday, Friday.
Results available in 1-3 days.

Reference Range

By report.

Test Methodology

Inductively Coupled Plasma/Mass Spectrometry (ICP/MS).

Interpretation

Iodine is an essential element that is required for thyroid hormone production.

The measurement of urinary iodine serves as an index of adequate dietary iodine intake.

Daily urinary output of less than 90 mcg/24 hours suggests dietary deficiency.

Values greater than 1000 mcg/specimen may indicate dietary excess, but more frequently suggest recent drug or contrast media exposure.

Administration of iodine-based contrast media and drugs containing iodine, such as amiodarone, will yield elevated results.

Clinical Utility

This assay is used to monitor iodine excretion rate as an index of daily iodine replacement therapy and for correlating total body iodine load with ¹³¹I uptake studies in assessing thyroid function.

CPT Codes

83789

Contacts

Last Updated

11/1/2024