Division of Nephrology and Hypertension, Geneva University Hospitals, Geneva, Switzerland.
Division of Nephrology and Hypertension, Geneva University Hospitals, Geneva, Switzerland.
J Ren Nutr. 2023 May;33(3):450-455. doi: 10.1053/j.jrn.2022.12.010. Epub 2023 Feb 2.
Several nonconsecutive 24-h urinary collections are considered the gold standard for estimating dietary salt intake. As those samples are logistically demanding, we aimed to describe the variability of 24-h sodium urinary excretion over consecutive days and report its adequacy with sodium intake.
We enrolled 16 healthy male volunteers in a prospective controlled study. All participants randomly received a low salt diet (LSD) (3 g/day of NaCl), a normal salt diet (NSD) (6 g/day of NaCl), and a high salt diet (HSD) (15 g/day of NaCl) for 7 days in a crossover design without wash-out period.
On day 6, median sodium urinary excretion was 258 (216-338), 10 (8-18), and 87 (69-121) mmol/day for HSD, LSD, and NSD, respectively (P < .001). When considering days 4-6, sodium urinary excretion was in steady state as models with and without interaction term "diet type X sample day" were not significantly different (P = .163). On day 6, area under the curve (AUC) of receiver operating characteristic for urinary sodium excretion to detect HSD was 1.0 (1.0-1.0) and a cut-point of 175 mmol/day was 100% sensitive and specific to detect HSD. On day 6, receiver operating characteristic AUC to detect LSD was 0.993 (0.978-1.0) and a cut-point of 53 mmol/day was 96.4% sensitive and 100% specific to detect LSD.
A steady state of sodium balance, where sodium intake is proportional to its excretion, is reached within a few days under a constant diet in the real-life setting. Categorization of salt consumption into low (3 g/day), normal (6 g/day), or high (15 g/day) based on a single 24-h urine collection is nearly perfect. Based on these results, repeated nonconsecutive urine collection might prove unnecessary to estimate sodium intake in daily clinical practice provided that diet is rather constant over time.
连续多次收集 24 小时尿液被认为是估计膳食盐摄入量的金标准。由于这些样本在操作上具有挑战性，我们旨在描述连续几天 24 小时尿钠排泄的变异性，并报告其与盐摄入量的相关性。
我们纳入了 16 名健康男性志愿者进行前瞻性对照研究。所有参与者随机接受低盐饮食（LSD）（3g 氯化钠/天）、正常盐饮食（NSD）（6g 氯化钠/天）和高盐饮食（HSD）（15g 氯化钠/天），交叉设计无洗脱期，共 7 天。
第 6 天，HSD、LSD 和 NSD 组的尿钠排泄中位数分别为 258（216-338）、10（8-18）和 10（8-18）mmol/天（P<0.001）。考虑到第 4-6 天，由于模型中没有“饮食类型 X 样本日”交互项，尿钠排泄处于稳定状态，两者无显著差异（P=0.163）。第 6 天，尿钠排泄的受试者工作特征曲线（ROC）下面积（AUC）检测 HSD 为 1.0（1.0-1.0），175mmol/天的截断值检测 HSD 的敏感性和特异性均为 100%。第 6 天，ROC AUC 检测 LSD 为 0.993（0.978-1.0），53mmol/天的截断值检测 LSD 的敏感性和特异性分别为 96.4%和 100%。
在现实生活中，连续几天内，在恒定饮食下，钠的摄入与排泄呈比例关系，达到钠平衡的稳定状态。根据单次 24 小时尿液收集结果，将盐摄入量分为低（3g/天）、正常（6g/天）或高（15g/天），几乎是完美的。基于这些结果，如果饮食在一段时间内相对稳定，那么在日常临床实践中，估计钠摄入量可能不需要重复进行非连续尿液收集。
