6-sulfatoxymelatonin collected from infant diapers: feasibility and implications for urinary biochemical markers

The purpose of this study was to assess feasibility and acceptability of using a diaper pad for collection of in-home infant urinary samples and to test the accuracy of diaper pad extraction for 6-sulfatoxymelatonin and creatinine, which was used to correct assay results for urinary volume. To assess feasibility and acceptability, urine samples from 20 infants were collected over a 24-hr day using a cotton pad inserted in the diaper. The accuracy of diaper pad extraction was evaluated in the laboratory using urine samples collected from 11 adult volunteers and assayed using enzyme immunosorbent assay (EIA). Urine samples were divided, one aliquot was assayed without extraction, and one aliquot was instilled into a diaper pad, extracted, and assayed. Mothers found diaper pad collection acceptable and easy to perform. Of 144 infant urinary samples obtained in the home environment, 59% were usable for assay purposes, and the remaining either were contaminated with stool or were of insufficient volume. While creatinine values from diaper pad extracted and nonextracted samples were highly correlated (r(2) = .947), those of creatinine-corrected 6-sulfatoxymelatonin were not (r(2) = .216). Diaper pad collection procedures altered 6-sulfatoxymelatonin values. Implications for measurement of urinary biochemical substances and statistical analysis are discussed.