Estimation of dietary salt intake from 24-hour and on spot urinary sodium excretion in Bangladesh.
Excessive salt intake is one of the main risk factors of hypertension. In Bangladesh, it is a significant contributor to the increased risk of non-communicable diseases. The study was conducted in 2012-2013 to estimate the salt consumption status and assess the relationship between excessive salt intake and high blood pressure among the middle-aged urban and rural Bangladeshi populations. Age, BMI, and blood pressure of the respondents were taken and expressed as Mean and SD or 95% CI. History of hypertension of the respondents and information regarding dietary salt intake patterns was gathered among the subjects by residence and expressed as frequency & percentage. Some urinary parameters like urinary sodium, potassium, creatinine, the ratio of sodium and potassium, and the urine volume were assessed among respondents by residence. The population salt consumption was estimated from both methods of 24-hour urinary sodium concentration and spot urine concentration like Tanaka, Kawasaki, and INTERSALT methods. Correlation between estimated salt intake by 24-hour urine and three spot urine methods were measured. Estimated consumed salt was measured by gram/day. Correlations between systolic and diastolic blood pressures and urinary parameters such as sodium (gm/day), Potassium (gm/day), and the ratio of Sodium and Potassium (mmol/L / mmol/L) were calculated. Salt intake from 24-hour urine and ratio of sodium and potassium excretion were divided into four quartiles to observe differences in blood pressure between quartiles. Multilinear regression was applied to observe correlations between blood pressure and salt intake estimated from 24-hour urine and ratio of Na: K excretion after adjusting for age and BMI. Here it is noted that the ratio of urinary Na: K excretion was positively correlated with both the systolic and diastolic blood pressure even after adjustment by age and BMI in multilinear regression. For this study, all analysis was done by using SPSS version 26.0, and the significance level was considered at a 95% confidence interval.
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The study was conducted in urban and rural sites of Dhaka. This was a population-based cross-sectional study, where both qualitative and quantitative data collection techniques were deployed. A screening questionnaire was administered. Information on sociodemographic characteristics, salt intake habits was collected by a questionnaire and all the physical measurements were measured in a standardized way. To estimate the daily salt intake in the selected populations, the 24-hour urinary sodium excretion method and three globally validated spot urine sample methods were considered. For the collection of urine samples, we followed the PAHO protocol. For the collection of 24-hour urine, participants were requested to void urine in the clinic toilet and a five ml sample of that urine (spot urine) was taken for biochemical measurement. The time of voiding was recorded and then respondents were given a jar and mug with a carrying bag and were requested to carry the bag for the next 24 hours and pour all urine in the jar. Respondents were requested to come to the clinic after 24 hours from the start of the collection of urine. On the next day, respondents were requested to void urine in the clinic and that urine was mixed with the collected urine of the last 24 hours. The total volume of the urine was measured by trained laboratory technicians and then four aliquots 5 ml urine (24-hr urine) were collected and kept in the freezer (-20 degree C) until measurement in the selected laboratory for this study. Urinary Sodium (Na), Potassium (K), and Creatinine (Cr) in spot and 24-hour collection samples were measured by using an auto-analyzer (Easylyte, Medica). Respondents were excluded from analysis due to incomplete urine collection and those presenting creatinine excretions were corrected for bodyweight outside the intervals of 14.4 – 33.6 mg/kg for men and 10.8 – 25.2 mg/kg for women. Estimation of daily salt intake from spot urine sample was calculated by Tanaka, Kawasaki, and INTERSALT equations.