Path Biol. 232 (9): 233–252. Diagnosis
The diagnostic workup of a suspected iodine deficiency includes signs and symptoms as well as possible risk factors mentioned above. A 24-hour urine iodine collection is a useful medical test, as approximately 90% of ingested iodine is excreted in the urine. For the standardized 24-hour test, a 50 mg iodine load is given first, and 90% of this load is expected to be recovered in the urine of the following 24 hours. Recovery of less than 90% is taken to mean high retention, that is, iodine deficiency. The recovery may, however, be well less than 90% during pregnancy, and an intake of goitrogens can alter the test results.If a 24-hour urine collection is not practical, a random urine iodine-to-creatinine ratio can alternatively be used. However, the 24-hour test is found to be more reliable.A general idea of whether a deficiency exists can be determined through a functional iodine test in the form of an iodine skin test. In this test, the skin is painted with an iodine solution: if the iodine patch disappears quickly, this is taken as a sign of iodine deficiency. However, no accepted norms exist on the expected time interval for the patch to disappear, and in persons with dark skin color the disappearance of the patch may be difficult to assess. If a urine test is taken shortly after, the results may be altered due to the iodine absorbed previously in a skin test.
In some cases, excessive iodine contributes to a risk of autoimmune thyroid diseases (Hashimotos thyroiditis and Graves disease). Different experts in nutrition advise different amounts of iodine supplementation. Supplementation is typically in a product which contains roughly half iodine and half iodide (a popular product used and sold for decades is “Iodoral®” which contains 5 mg of Iodine and 7.5 mg of Iodide). On low side there is Kara Fitzgerald recommending less than 1,100 mcg per day (except when treating some medical conditions), she considers long term dosage of 40,000 mcg per day “excessive”. In the middle we have Dr. Alan Gaby who considers a “moderately high dose” to be 3,000 to 6,000 mcg per day. On the higher end we have Dr. David Brownstein, Dr. Jorge Flechas, Dr. Guy Abraham, Dr. Alan Roby and Dr. Jonathan Wright who recommend 6,000 mcg to 50,000 mcg per day. Prognosis
With iodine supplementation, goiters caused by iodine deficiency decrease in size in very young children and pregnant women. Generally, however, long-standing goiters caused by iodine deficiency respond with only small amounts of shrinkage after iodine supplementation, and patients are at risk for developing hyperthyroidism.Being pregnant while iodine-deficient additionally carries the risk of causing congenital iodine deficiency syndrome in the newborn. This disease can only be managed by lifelong administration of thyroxine (T4). Epidemiology
Iodine deficiency resulting in goiter occurs in 187 million people globally as of 2010 (2.7% of the population).