As 24-hour urine collection is inpractical, this study compared the relationship between urinary sodium, potassium excretion and blood pressure in spot urine and 24-hour urine samples in Chinese people living in nursing houses in China.Methods:
Cross-sectional investigation was carried out in 27 nursing houses. Survey items included questionnaire physical examination, spot urine (within7:00–9:00AM) and fasting blood sample collection. Totally 1127 people with complete data were used for data analysis. 0ut of 1127 persons, 248 had one 24-hour urine collection sample. Stepwise Multiple regression analysis using SBP DBP as independent variables, age, BMI, total cholesterol (TC), Una, UK and UNa/K as dependent variables showed the following results.Results:
The mean age, SBP, DBP, BMI, total cholesterol (TC)and spot Una/K was 69.8 ± 11.17, 146.8 ± 24.62, 79.6 ± 11.69, 23.8 ± 3.75, 4.49 ± 1.00 and 3.23 ± 2.49 respectively in all participants. For 248 persons with 24H urine samples, The mean age, SBP, DBP, UNa, UK and UNa/K was 72.4 ± 10.00, 148.36 ± 24.68, 79.59 ± 10.66, 149.37 ± 81.08 (mmol), 39.95 ± 25.96 (mmol) and 4.94 ± 3.66 respectively. Multiple regression showed that age, BMI, TC and UNa/K were significantly positively correlated with SBP in both spot urine or 24H urine samples. (all P < 0.05). In spot urine model, age was negatively correlated to DBP (P = 0.000), but BMI, UNa/K and TC were positively related to DBP (all P < 0.05). In 24H urine model, age was also negatively correlated to DBP (P = 0.000), BMI, while UNa/K were positively correlated to DBP (all P < 0.05). In all regression models, UNa and UK variables were all removed.Conclusion:
The results demonstrate that urinary sodium to potassium ratio is more closely correlated with blood pressure than Na or K in both spot urine and 24H urine Samples.