Diurnal electrolyte excretion pattern affects estimates of electrolyte status based on 24-hour, half-day, and overnight urine.
This study set out to examine the diurnal pattern of electrolyte excretion in urine, and to investigate whether urine collected from after dinner until next morning (half-day evening urine) might to be an alternative to 24-h urine more valid than overnight urine for ranking a person's electrolyte status. In a cross-sectional study of 40 young adults, two consecutive 24-h urine samples were collected, followed one month later by two further consecutive 24-h samples. Mean excretion rates of sodium and chloride steadily increased during the daytime. Electrolyte/creatinine ratios also increased, but all excretion rates decreased after sleep. The potassium excretion rate increased rapidly in the morning but declined steadily after 10 a.m.. Estimates of 24-h electrolyte content calculated from half-day amounts were approximately 80-92% of the actual 24-h urinary electrolyte values. Estimates obtained using overnight urine amounts approximated 60% of the actual 24-h values. Correlation coefficients between actual 24-h urinary electrolytes and estimates based on half-day urine were better than correlates between actual 24-h amounts and estimates obtained using timed overnight urine. These results suggest that half-day evening urine may be a useful alternative to 24-h urine for assessing electrolyte in-take.
Division of Epidemiology and Public Health, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, ROC.
W H
WH
Pan
J Y
JY
Chen
Y C
YC
Chen
W Y
WY
Tsai
D000328:Adult; D002712:Chlorides / Q000652:urine*; D002940:Circadian Rhythm; D003404:Creatinine / Q000652:urine; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D011188:Potassium / Q000652:urine*; D012964:Sodium / Q000652:urine*
D002712:Chlorides; D012964:Sodium; D003404:Creatinine; D011188:Potassium