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)
Sorry, practitioner has been doing this for 15 years. 100's of patients. My wife has been doing it for 5 patients a day for years. 100% success rate.
Good for you. But if you look at the literature it is well known that it's not the most accurate test (did you look at that link?) . I'm simply saying if you want the best test then the 24 hour urine test is the best.