I . Iodine metabolism was studied using labelled sodium iodide in subjects with endemic goitre which is prevalent in the south-west part of Ceylon, where the iodine content of the drinking water was shown to be low. The study was confined mostly to children of school age. 2. The patients showed raised thyroidal uptake of lS1I and 48 h serum protein-bound radioactive iodine, lowered plasma inorg...