Measurement of urine pH for epidemiological studie

Authors: Juan Alguacil Ruth M Pfeiffer Lee E Moore Manuel Rivas del Fresno Rafael MedinaLopez Manolis Kogevinas Roel Vermeulen Mustafa Dosemeci Debra T Silverman Nathaniel Rothman Montserrat GarcíaClosas

Publish Date: 2007/03/03

Volume: 22, Issue: 2, Pages: 91-

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Abstract

Methods for efficiently identifying subjects with constantly acidic pH in epidemiological and clinical studies have not been assessed We recruited 30 volunteers to estimate the minimum number of urine pH measurements using pH strips needed to identify subjects with “constantly acidic urine pH” Spearman’s correlation coefficients between urine pH measured with a pH meter and with the four pH strips ranged from 094 to 095 p 0001 for all four strips Overall agreement within ±05 pH units between the four strips and the pH meter ranged from 622 to 744 When using a spot urine sample from a single morning to classify participants with respect to their urine pH 80 of individuals fell into the acidic urine pH pH equal to or lower than 60 group When we required subjects to have urine pH equal to or lower than 60 in six consecutive AM spot urine samples and seven spot PM urine samples only 20 of participants fulfilled this criterion Measuring urine pH twice a day early in the morning and early in the evening during four consecutive days classified individuals in the same way as two daily measurements for one week A single pH measurement from a spot urine sample is not reliable to identify individuals with constantly acidic pH Morning and evening urine pH measurements with pH strips during four consecutive days identify individuals with constantly acidic urine pH individuals as well as one week of measurements and thus might be useful to identify subjects with constantly acidic urine pH in epidemiological and clinical studies

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