Nope, this is not true. This is not an accurate way of testing for iodine.
You cannot consider that you are deficient or sufficient based on the patch test on the skin.
There are too many variables that change its absorption. It isn’t very scientific.
Have a look at this review paper on the accuracy of the skin test:
http://www.optimox.com/pics/Iodine/updates/UNIOD-02/UNIOD_02.htm
The 24 hour urine test is the best test (though even that has some flaws)
RE: Health Tip Of The Day: [Iodine]