The first general accepted method of testing iodine levels is by measuring the amount of iodine in the urine.  However, that is not as reliable method as you think.  In recent study by Dr. Abraham and coinvestigators have developed an iodine-loading test that is based ion the concept that the more iodine deficiency there is, the more iodine is retained in the body and the less iodine is excreted in the urine.  Nevertheless, the iodine-loading test has been found to provide very useful information on the body’s iodine status.  Now that the iodine binds to iodine receptors throughout the body.  If the body’s receptors for iodine are sufficient in iodine, a large percentage of ingested iodine will be excreted from the body.  On the other hand, if there is an iodine deficiency present, ingested iodine will be retrained at a much larger percentage.  The iodine-loading test is performed after taking 50mg of an iodine/iodie combination.  Urine is collected for 24 hours after taking the iodine.  In an iodine sufficient state, approximately 90% of a mixture of a 50mg dose of iodine/iodide would be excerpted and 10% of the iodine would be retained.  Levels below 90% excretion would indicate an iodine-deficient state.