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Normal Values for the Urine Iodine Clearance Test

written by: Lashan Clarke•edited by: Emma Lloyd•updated: 7/13/2010

The patient is placed on a restrictive iodine diet before the test. A sample of urine is taken as an early morning void to measure the level of iodine before loading. This will form the first test result and be compared to the iodine clearance test urine normal values.

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    Iodine & The Thyroid Gland

    Iodine is a mineral that is needed by the body to create the hormone thyroxine. Thyroxine is produced by the thyroid gland The thyroid gland is located in the neck in front of the trachea. This gland produces a hormone called thyroxine, which is responsible for overseeing the organs of the body that are responsible for metabolism. Therefore, if the body is deficient in iodine, it can produce a condition known as goiter in which the thyroid gland enlarges due to lack of iodine and increased cell size to overcompensate.

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    Why Is The Test Ordered?

    Evaluating the iodine clearance test urine normal values are based on seeing if the person is deficient in iodine or iodide. If there is a lack of iodine, the person will experience mental difficulties such as difficulty concentrating, decreased energy, and potential reproductive problems. This test is a great way to see if the person is getting enough iodine in the diet from sources such as flour pastries, seafood, tap water, soft drinks, and toothpaste.

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    How Is The Test Performed?

    The way in which the iodine clearance test urine normal values test is by providing a sample of iodine to the patient an seeing how long it takes to for the body to excreted.

    Therefore, the patient is told to fast and placed on a restrictive iodine diet before the test. A sample of urine is taken as an early morning void to measure the level of iodine before loading. This is known as a SPOT test and it establishes the baseline value for the person. Next the patient is given 50 mg of iodine as a loading dose. A 24-hour urine collection for the amount of iodine or iodide excreted is taken after this load dose. This test will also compare the urinary iodine values to the normal creatinine value that is excreted by the kidney in urine. Creatinine is a byproduct of muscle metabolism and is an indicator of kidney function.

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    Discussing The Test Results

    The urine iodine clearance test will give two values. One value tells the amount in milligrams of iodine excreted. The second value tells how much of this excreted is a percentage of the total iodine ingested. The results for the iodine clearance test urine normal values should expect the amount of iodine to be between 0.02 to 0.38 mg as the amount of iodide cleared by the kidneys in a 24-hour period. To discover the percentage of it excreted, the amount of iodine released in milligrams is divided by the total milligrams of iodine given as a loading dose. The normal value of the percentage of iodine excreted should be approximately 40 percent. This result can tell a physician how the person will respond to iodine treatment, and also can suggest a problem with the thyroid gland or kidneys if the value is abnormal.

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    References

    Web Source: Thyroid Disease Manager. "The Iodine Deficiency Disorders." 2009. Available: http://www.thyroidmanager.org/Chapter20/index.html

    Web Source: Doctor's Data, Inc. "24 Hour Urine Iodine." 2010. Available: http://www.directlabs.com/imagepage.aspx?id=569&type=testsample

    Web Source: Optimox Corporation. "The Iodine/Iodide Loading Test." 2010. Available: http://www.optimox.com/pics/Iodine/loadTest.htm