TY - JOUR
T1 - Urinary excretion of sodium, Potassium, and Chloride, but not Iodine, varies by timing of collection in a 24-hour calibration study
AU - Wang, Chia Yih
AU - Cogswell, Mary M.
AU - Loria, Catherine C.
AU - Chen, Te Ching
AU - Pfeiffer, Christine C.
AU - Swanson, Christine C.
AU - Caldwell, Kathleen K.
AU - Perrine, Cria C.
AU - Carriquiry, Alicia A.
AU - Liu, Kiang
AU - Sempos, Christopher C.
AU - Gillespie, Cathleen C.
AU - Burt, Vicki V.
PY - 2013
Y1 - 2013
N2 - Because of the logistic complexity, excessive respondent burden, and high cost of conducting 24-h urine collections in a national survey, alternative strategies to monitor sodium intake at the population level need to be evaluated. We conducted a calibration study to assess the ability to characterize sodium intake from timed-spot urine samples calibrated to a 24-h urine collection. In this report, we described the overall design and basic results of the study. Adults aged 18-39 y were recruited to collect urine for a 24-h period, placing each void in a separate container. Four timed-spot specimens (morning, afternoon, evening, and overnight) and the 24-h collection were analyzed for sodium, potassium, chloride, creatinine, and iodine. Of 481 eligible persons, 407 (54% female, 48% black) completed a 24-h urine collection. A subsample (n = 133) collected a second 24-h urine 4-11 d later. Mean sodium excretion was 3.54 ± 1.51 g/d for males and 3.09 ± 1.26 g/d for females. Sensitivity analysis excluding those who did not meet the expected creatinine excretion criterion showed the same results. Day-to-day variability for sodium, potassium, chloride, and iodine was observed among those collecting two 24-h urine samples (CV = 16-29% for 24-h urine samples and 21-41% for timed-spot specimens). Among all race-gender groups, overnight specimens had larger volumes (P ≪ 0.01) and lower sodium (P ≪ 0.01 to P = 0.26), potassium (P ≪ 0.01), and chloride (P ≪ 0.01) concentrations compared with other timed-spot urine samples, although the differences were not always significant. Urine creatinine and iodine concentrations did not differ by the timing of collection. The observed day-to-day and diurnal variations in sodium excretion illustrate the importance of accounting for these factors when developing calibration equations from this study.
AB - Because of the logistic complexity, excessive respondent burden, and high cost of conducting 24-h urine collections in a national survey, alternative strategies to monitor sodium intake at the population level need to be evaluated. We conducted a calibration study to assess the ability to characterize sodium intake from timed-spot urine samples calibrated to a 24-h urine collection. In this report, we described the overall design and basic results of the study. Adults aged 18-39 y were recruited to collect urine for a 24-h period, placing each void in a separate container. Four timed-spot specimens (morning, afternoon, evening, and overnight) and the 24-h collection were analyzed for sodium, potassium, chloride, creatinine, and iodine. Of 481 eligible persons, 407 (54% female, 48% black) completed a 24-h urine collection. A subsample (n = 133) collected a second 24-h urine 4-11 d later. Mean sodium excretion was 3.54 ± 1.51 g/d for males and 3.09 ± 1.26 g/d for females. Sensitivity analysis excluding those who did not meet the expected creatinine excretion criterion showed the same results. Day-to-day variability for sodium, potassium, chloride, and iodine was observed among those collecting two 24-h urine samples (CV = 16-29% for 24-h urine samples and 21-41% for timed-spot specimens). Among all race-gender groups, overnight specimens had larger volumes (P ≪ 0.01) and lower sodium (P ≪ 0.01 to P = 0.26), potassium (P ≪ 0.01), and chloride (P ≪ 0.01) concentrations compared with other timed-spot urine samples, although the differences were not always significant. Urine creatinine and iodine concentrations did not differ by the timing of collection. The observed day-to-day and diurnal variations in sodium excretion illustrate the importance of accounting for these factors when developing calibration equations from this study.
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U2 - 10.3945/jn.113.175927
DO - 10.3945/jn.113.175927
M3 - Article
C2 - 23761643
AN - SCOPUS:84881340847
SN - 0022-3166
VL - 143
SP - 1276
EP - 1282
JO - Journal of Nutrition
JF - Journal of Nutrition
IS - 8
ER -