Specific Aims
1. To collect multiple spot urine samples and a 24-h urine sample in a population of Chinese Children and adults. All participants will collect a spot urine in separate jugs during the 24-h period, recording every urination time.
2. Validate previous finding that 24-h USE is estimated inaccurately by using only the second morning void.
3. Explore a statistical formula to estimate 24-h USE by multi-time spot urine. The study plan to enroll 200 children and 100 adults to collect a whole 24-h urine spot by spot continuously. After a laboratory examination of sodium concentration from both spot urine samples and 24-h urine sample, the exploratory estimation using multi-spot urine to assess 24-h urinary sodium excretion will analyzed statistically. The validation for the estimation method will be conducted in Chinese population as well.
Urine sodium and potassium concentration in each urine specimen will be determined by ion selective electrode methods and creatinine using enzymatic methods.The model established by using linear model step by step. And the validation analysis conducted through correlation analysis, bias distribution, residual analysis and Bland-Altman plot to assess accuracy. All statistics analysis will be conducted using Statistical Analysis System software version 9.4.
