Simple method for sampling consecutive 24-hour urine for epidemiological and clinical studies.

'Aliquot cups' a newly devised tool for collecting 24-hour urine samples were useful and accurate enough for the estimation of individual 24-hour excretion of sodium and potassium. Data from 24-hour collections for 31 days for 5 healthy volunteers showed relatively large intra- and inter-individual variation. These data suggest that at least 5 consecutive days of urine collection would be needed to make a reasonable estimate of daily intake.