We measured the iodine content of gallstones and bile from patients in three areas (Kawasaki in Japan, and Chiang Mai and Bangkok in Thailand) by means of neutron activation analysis. The mean values for iodine content in three types of gallstones (cholesterol, pigment and rare stones) and bile from patients living in Chiang Mai were clearly smaller than those from patients living in Kawasaki and Bangkok. The low iodine intake by Chiang Mai patients continued from the start of gallstone formation until the time when the stones were excised, and the iodine intake was low when bile was collected. The PBI levels in the sera of Chiang Mai residents with low iodine intake over a long period were clearly lower than those of Bangkok patients with normal intake, and the levels in goiter patients were similar to those in healthy people and patients with gallstones among Chiang Mai residents.

Source: http://www.ncbi.nlm.nih.gov/pubmed/10410500