A controlled trial of iodinated oil for the prevention of endemic cretinism: a long-term follow-up.

A double blind controlled trial designed to examine the effectiveness of intramuscular iodinated oil as a prophylactic for the nervous type of endemic cretinism was begun in 1966 in the highlands of Papua New Guinea. Infants born into the trial between 1966 and 1972 were followed up until 1982. The results showed that if the iodine supplement was given before conception the nervous form of endemic cretinism was prevented. Also a striking difference in the 15-year cumulative survival rate in favour of the test (iodinated oil) group was observed. Measures of motor and intellectual function revealed that children born to mothers given an iodine supplement performed significantly better. This observation shows that iodine deficiency leads to sub-clinical as well as clinical deficits. It also justifies the use of the term iodine deficiency disorder to cover the polymorphic nature of the abnormalities attributable to iodine deficiency.