To validate of urinary sodium and potassium excretion between using 24-h urine and nocturnal urine for Chinese healthy population.Methods:
100 healthy participants were required collected each spot urine sample in an independent container every time in the whole 24-hour day. The span of nocturnal was defined as the time began from after the last urine before bed or sleeping, till after the first spot urine in the next morning. After the laboratory examination, the urinary excretion concentration of sodium (Na), potassium (K), creatinine (Cr) and the ratio of sodium and potassium (Na / K) in the nocturnal and those in the 24-h urine samples were compared and conducted the consistancy analysis, using correlation, bias distribution and Bland-Altman plots to assess.Results:
There were finally 87 pairs of urine samples from 87 healthy participants, 33 males and 54 females, for consistency analysis after the data cleaning procedure. The mean level of nocturnal urinary sodium excretion were 1043 ± 647 mg in males and 917 ± 549 in females. The correlation coefficients of Na, K, Cr and Na / K between nocturnal urine and 24-h urine samples were 0.542, 0.771, 0.736, and 0.691 respectively (P < 0.001). From the Bland-Altman plots were also indicated the acceptable consistency for Na, K, and Na / K between nocturnal urine and 24-h urine samples.Conclusion:
Nocturnal urine might be a substitutes for 24-h urine, but should be corrected by Cr excretion and classified by gender, when use to assess the urinary sodium excretion.