[Preventive iodine administration and iodine excretion in the Vienna area and in the forest quarter]

In order to reduce the still substantial iodine deficiency in the Austrian population, compulsory iodisation of salt was increased in 1990 from 10 mg potassium iodide/kg salt to 20 mg potassium iodide/kg. In this investigation we evaluated the adequacy of iodine supply in Vienna and the Waldviertel, a rural region northwest of Vienna. Daily iodine excretion (which reflects daily iodine intake) was investigated in 92 persons from the Waldviertel (all without thyroid gland pathology) and 110 persons from Vienna (54 with unremarkable thyroid glands, 56 with endemic goiter). Daily iodine excretion was higher in persons from the Waldviertel (161 +/- 90.7 micrograms/24 h, p < 0.05) than in those from Vienna (with healthy thyroid glands 126.4 +/- 42.9 micrograms/24 h and with goiter 117.2 +/- 60.5 micrograms/24 h, resp.). In both populations iodine supply as defined by the WHO (excretion of > 150 ug iodine/day) was inadequate. The recommended level was not achieved in 50% of the persons from the Waldviertel region and in 75% of persons from Vienna (healthy thyroid glands 76%, goiter: 75%). Iodine deficiency (intake < 100 micrograms/24 h) was present in 42% persons from the Waldviertel and in 31% and 24% persons, respectively, from Vienna with unremarkable thyroid glands and goiter. We conclude that although the iodine content of salt was increased, an iodine deficiency was present in a considerable portion of the population of an industrialized country (approximately 40% of persons from a rural region and 30% from the city of Vienna).