Use of mean spot urine sodium concentrations to estimate daily sodium intake in patients with chronic kidney disease.
ABSTRACT Sodium intake is an important issue for patients with chronic kidney disease (CKD). The two most widely used methods to measure sodium are 24-h urinary sodium excretion (24HUNa), which can be difficult to perform routinely, and sodium intake by dietary recall, which can be inaccurate. This study evaluated use of the mean value of three spot urinary sodium (UNa) concentrations to estimate daily sodium intake in patients with CKD.
This cross-sectional study enrolled 305 patients with CKD, none of whom were on dialysis, who visited the nephrology clinic at the Asan Medical Center (Seoul, Korea). We performed three spot UNa tests, three calculations of the UNa/creatinine (UCr) ratio, one measurement of 24HUNa, and one measurement of sodium intake by dietary recall.
The 24HUNa and mean spot UNa values were significantly lower in patients with more advanced CKD (P = 0.006 and P < 0.001, respectively). One-time spot UNa was significantly higher in the evening than in the morning for patients with stage III, IV, or V CKD. Total sodium intake, but not sodium nutrient density (milligrams of sodium per 1000 kcal), was significantly different for patients with different stages of CKD (P = 0.001). The correlation coefficient between 24HUNa and mean spot UNa was 0.477 (95% confidence interval [CI] 0.384-0.562, P < 0.001), slightly higher than that between 24HUNa excretion and mean spot UNa/UCr (r = 0.313, 95% CI 0.207-0.465, P < 0.001). There was a linear relation between spot UNa and 24HUNa: mean spot UNa = 0.27 × 24HUNa + 60. Therefore, a 24HUNa excretion of 87 mEq (sodium intake 2 g/d) corresponded to a mean spot UNa level of 83 mEq/L. The correlation coefficient between sodium intake and mean spot UNa was 0.435 (95% CI 0.336-0.524, P < 0.001), significantly higher than that between sodium intake and mean spot UNa/UCr (r = 0.197, 95% CI 0.091-0.301, P = 0.001). Mean spot UNa tended to be better correlated with 24HUNa than with sodium intake.
Mean spot UNa is a simple and effective method that can be used to monitor sodium intake in patients with CKD. A daily intake of 2 g of sodium corresponds to a mean spot UNa level of approximately 83 mEq/L in patients with CKD.
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ABSTRACT: This study aimed to assess the salt intake of Iranian children, and to assess the correlation of urinary electrolytes excretion with blood pressure. This cross-sectional study was conducted in 2011-2012 among 3-10-year-old children, selected by multi-stage cluster sampling from urban and rural areas of Isfahan, Iran. The sodium (Na), potassium (K), and creatinine (Cr) were measured in a random sample of the children's first morning fasting urine. Three-day averages of dietary intakes were analyzed by the Nutritionist-4 software. The mean (SD) of urinary Na was 177.17 (28.68) mEq/day without significant difference according to gender and living area. The mean (SD) dietary intakes of Na and K were 2017.76 (117.94) and 1119.06 (76.03) mg/day, respectively. Children of urban and rural areas consumed similar sources of salty foods (bread, cheese, and snacks) and had low intake of vegetables. No significant association was documented between urinary electrolytes excretions and blood pressure. This study, which to the best of our knowledge is the first of its kind in the Middle East and North Africa region, revealed that Iranian young children consume a large amount of sodium and small amount of potassium. The non-significant associations of electrolyte excretions with blood pressure may be because of the very young age group of participants. Given the development of preference to salt taste from early childhood, and the tracking of risk factors of chronic diseases from this age, reducing salt intake of young children should be emphasized.International journal of preventive medicine 04/2013; 4(4):475-83.
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ABSTRACT: BACKGROUND: Despite evidence implicating dietary sodium in the pathogenesis of cardiovascular disease (CVD) in chronic kidney disease (CKD), quality intervention trials in CKD patients are lacking. This study aims to investigate the effect of reducing sodium intake on blood pressure, risk factors for progression of CKD and other cardiovascular risk factors in CKD. Methods/design The LowSALT CKD study is a six week randomized-crossover trial assessing the effect of a moderate (180 mmol/day) compared with a low (60 mmol/day) sodium intake on cardiovascular risk factors and risk factors for kidney function decline in mild-moderate CKD (stage III-IV). The primary outcome of interest is 24-hour ambulatory blood pressure, with secondary outcomes including arterial stiffness (pulse wave velocity), proteinuria and fluid status. The randomized crossover trial (Phase 1) is supported by an ancillary trial (Phase 2) of longitudinal-observational design to assess the longer term effectiveness of sodium restriction. Phase 2 will continue measurement of outcomes as per Phase 1, with the addition of patient-centered outcomes, such as dietary adherence to sodium restriction (degree of adherence and barriers/enablers), quality of life and taste assessment. DISCUSSION: The LowSALT CKD study is an investigator-initiated study specifically designed to assess the proof-of-concept and efficacy of sodium restriction in patients with established CKD. Phase 2 will assess the longer term effectiveness of sodium restriction in the same participants, enhancing the translation of Phase 1 results into practice. This trial will provide much-needed insight into sodium restriction as a treatment option to reduce risk of CVD and CKD progression in CKD patients. Trial registration Universal Trial Number: U1111-1125-2149. Australian New Zealand Clinical Trials Registry Number: ACTRN12611001097932.BMC Nephrology 10/2012; 13(1):137. · 1.64 Impact Factor
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ABSTRACT: A salt preference questionnaire may be a convenient and cost-effective method for predicting salt intake; however, the influence of salt preference on daily salt intake is unclear. This study aimed at revealing the effectiveness of the salt preference question in determining the daily salt intake in primary care outpatients. This cross-sectional study included 1,075 outpatients (men, n=436, 40.6%) at six primary care institutions in Japan. Primary outcomes included a salty food preference assessed by using one question and a daily salt intake, assessed using early morning second urine samples. Multivariate analyses determined the relationships between the salt intake and the two salt preference levels. The mean age was 67.6±14.6 years, and 594 (55.3%) preferred salty foods. The daily salt intake was 12.3±4.0 g per day and 11.4±3.7 g per day in the salt preference and nonsalt preference groups, respectively (P<0.001). A salt intake <10 g per day was consumed by 169 (28.5%) and 181 (37.6%) patients (P=0.001), respectively, and <6 g salt per day was consumed by 28 (4.7%) and 26 (5.4%) patients (P=0.606), respectively. The patients who preferred salty foods consumed a significantly larger amount of salt per day than those who did not prefer salty foods (β coefficient, 0.621; 95% confidence interval [CI], 0.146-1.095). There was no difference in the number of patients who consumed <10 g salt per day (adjusted odds ratio [ad-OR], 1.29; 95% CI, 0.99-1.69) or <6 g salt per day (ad-OR, 1.39; 0.90-1.69) between the groups. Preference for salty foods was positively associated with daily salt intake. However, daily salt intake was not always appropriate, even in the patients who did not prefer salty foods. Behavioral interventions for salt restriction after an assessment of daily salt intake are necessary for primary care patients, regardless of their preference for salty foods.International Journal of General Medicine 01/2014; 7:205-210.