Intra- and Inter-individual Variation of Urinary Selenium, Molybdenum and Iodine Concentration in Healthy Young Japanese Adults

Summary To examine intra- and inter-individual variation of urinary selenium, molybdenum and iodine concentration, a spot sample of morning urine was continuously collected from 12 healthy Japanese young adults (7 males and 5 females) for seven days and selenium, molybdenum and iodine in these urine samples were determined by inductively cou - pled plasma mass spectrometry. Minimum, mean, median, geometrical mean and maximum values (µg/g creatinine) for the all samples were as follows: selenium, 18, 36, 35, 34 and 72, respectively; molybdenum, 14, 69, 57, 57 and 206, respectively; iodine, 15, 160, 89, 99 and 1105, respectively. Coefficients of variation for the all samples were estimated to be 27.8% for selenium, 83.8% for molybdenum and 118.1% for iodine. Ratios of intra- to inter-variance were calcu- lated as 1.88 for selenium, 2.32 for molybdenum and 2.58 for iodine. These results indicate that the variation of uri- nary iodine was higher than that of selenium or molybdenum, and the intra-individual variation was higher than the inter-individual variation in urinary selenium, molybdenum and iodine. Based on the logarithmical transformed data, median and 5th to 95th percentile of usual urinary excretion (µg/g creatinine) was estimated to be 37 and 26 to 46 for selenium, 60 and 33 to 110 for molybdenum, and 163 and 31 to 576 for iodine, respectively.