[Iodine deficiency is still endemic in Switzerland]

To obtain information on the present state of iodine supply in Switzerland random urine samples have been collected from 770 individuals for the purpose of measuring iodine and creatinine excretion. As a first step the widely used method of measuring iodine concentration per gram creatinine in casual urine samples was validated by quantitatively collecting urines for 6 consecutive 4 h periods in 11 healthy volunteers. True ioduria could thereby be compared with that calculated from random samples. 83% of all values were found to be within +/- 30% of the true mean value. The mean iodine content of all 770 samples collected in the field study was 93.3 microgram per gram creatinine (I/Cr). This mean value is slightly below the adequate iodine supply. Of even more concern is the fact that less than 60 microgram I/g Cr was found in 20% of all samples. Therefore, in the population sample as a whole the mean ioduria is still clearly below that indicating a sufficient iodine supply, and in one out of five individuals iodine excretion was typical of marked iodine deficiency. Low ioduria correlated significantly with low natriuria in both male and female subjects. This finding indicates that iodized table salt is an important though inadequate source of alimentary iodine. The increase in iodine admixture to table salt already agreed upon appears to be an appropriate means of improving nutritional iodine availability. Iodine deficiency may still be an important cofactor in the high prevalence of goiter in Switzerland. The long established goiter prophylaxis by iodine admixture to table salt may have lost part of its efficiency due to the sharp decrease in per capita consumption of salt.