USE OF SELENIUM CONCENTRATION IN WHOLE-BLOOD, SERUM, TOENAILS, OR URINE AS A SURROGATE MEASURE OF SELENIUM INTAKE

We examined the validity of using the selenium level in a single biolo gical specimen as a surrogate measure of usual intake. We used data fr om 77 free-living adults from South Dakota and Wyoming. Subjects provi ded multiple 1-day duplicate-plate food composites, repeated specimens of blood and toenails, and 24-hour urine collections. We developed a statistical calibration method that incorporated measurement: error co rrection to analyze the data. The Pearson correlation coefficients bet ween selenium intake and a single selenium status measure, after deatt enuation to adjust for the effect of within-person variation in intake , were: 0.78 for whole blood, 0.74 for serum, 0.67 for toenails, and 0 .86 for urine. We present formulas to estimate the intake of individua ls, based on selenium levels in a single specimen of blood, toenails, or urine. In these data, the concentration of selenium in a single spe cimen of whole blood, serum, or toenails served reasonably well as a m easure for ranking subjects according to long-term selenium intake but provided only a rough estimate of intake for each subject.