Iodine is one of the building blocks the thyroid uses to produce the hormones necessary for proper metabolic function. As you might guess, without enough iodine, you can experience a number of problems, such as hypothyroidism. One of the most popular ways to test for iodine deficiency is the iodine patch test. The Iodine Patch Test theoretically measures how quickly the body absorbs iodine through the skin. The issue with this test is that it’s not 100% reliable and doesn’t provide an extensive view of your iodine levels as could a test done by your doctor.
What is the Iodine Patch Test?
The iodine patch test supposedly measures how quickly your body absorbs iodine. Again, this isn’t a proper substitute for a clinically-performed test that will actually measure your iodine levels accurately. Despite the popularity of the iodine patch test, no research supports its ability to measure iodine levels. That being said, here are the steps to perform it:
- Get a solution or tincture of iodine (the orange solution, not the clear one.
- Paint a 3-inch by 3-inch square on your abdomen, inner thigh or inner forearm. Allow it to dry before touching anything, as it will stain.
- Monitor the patch over the next 24 hours for color changes.
Proponents of the test believe that the thing to pay attention to is how long it takes for the iodine patch to disappear. If the patch still exists 24 hours later, the results are normal. If the patch disappears or mostly disappears in less than 24 hours, it is supposed to indicate some degree of deficiency. In fact, significant lightening or disappearance in less than 18 hours is said to indicate moderate to severe iodine deficiency and suggest a need for supplemental iodine.
Is the Iodine Patch Test Actually Reliable?
Although several recent studies have demonstrated increases in iodine levels through skin absorption suggesting the result of this test may reflect a deficiency or adequacy of iodine, a lot of other factors suggest otherwise.   
A number of factors play a role in the disappearance of the yellow color of iodine from the surface of the skin. For example, if iodine is reduced to iodide by the skin, the yellow color of iodine will disappear because iodide is white. The evaporation of iodine can also be affected by ambient temperatures and atmospheric pressure. If you’re looking for a way to test your iodine status, the loading test is much more accurate.
Watch an In-Depth Video on
Everything You Need to Know About Iodine
- Miller KL, Coen PE, White WJ, Hurst WJ, Achey BE, Lang CM. Effectiveness of skin absorption of tincture of I in blocking radioiodine from the human thyroid gland. Health Phys. 1989 Jun;56(6):911-4.
- Zimmermann MB, Crill CM. Iodine in enteral and parenteral nutrition. Best Pract Res Clin Endocrinol Metab. 2010 Feb;24(1):143-58. doi: 10.1016/j.beem.2009.09.003.
- Tomoda C, Kitano H, Uruno T, Takamura Y, Ito Y, Miya A, Kobayashi K, Matsuzuka F, Amino N, Kuma K, Miyauchi A. Transcutaneous iodine absorption in adult patients with thyroid cancer disinfected with povidone-iodine at operation. Thyroid. 2005 Jun;15(6):600-3.