What is Fasting and does it really matter

From the initial sample selected to collect the 24-hr urine, a one-half subsample is selected to do the second 24-Hour urine collection. Participants with remainders 1, 5, 10, 11, and 18 (half of the weekend sample and half of the weekday sample) will be asked to collect a second 24-hour urine sample. ................
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