Lerchl Kathrin, Rakova Natalia, Dahlmann Anke, Rauh Manfred, Goller Ulrike, Basner Mathias, Dinges David F, Beck Luis, Agureev Alexander, Larina Irina, Baranov Victor, Morukov Boris, Eckardt Kai-Uwe, Vassilieva Galina, Wabel Peter, Vienken Jörg, Kirsch Karl, Johannes Bernd, Krannich Alexander, Luft Friedrich C, Titze Jens
From the Interdisciplinary Center for Clinical Research (K.L., N.R., U.G., J.T.), Department of Nephrology and Hypertension (A.D., K.-U.E., J.T.), and Department of Pediatrics (M.R.), Friedrich-Alexander-University, Erlangen-Nürnberg, Germany; Experimental and Clinical Research Center, an institutional cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany (N.R., F.C.L.); Unit for Experimental Psychiatry, Division of Sleep and Chronobiology, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia (M.B., D.F.D.); Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany (L.B., B.J.); State Scientific Center of Russian Federation, Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, Russia (A.A., I.L., V.B., B.M., G.V.); Fresenius Medical Care-D GmbH, Bad Homburg, Germany (P.W., J.V.); Center for Space Medicine, Institute of Physiology, Charité - University Clinic Berlin, Berlin, Germany (K.K.); Department of Biostatistics, Coordination Center for Clinical Trials, Charité University Medicine Berlin, Berlin, Germany (A.K.); and Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN (F.C.L., J.T.).
Hypertension. 2015 Oct;66(4):850-7. doi: 10.1161/HYPERTENSIONAHA.115.05851. Epub 2015 Aug 10.
Accurately collected 24-hour urine collections are presumed to be valid for estimating salt intake in individuals. We performed 2 independent ultralong-term salt balance studies lasting 105 (4 men) and 205 (6 men) days in 10 men simulating a flight to Mars. We controlled dietary intake of all constituents for months at salt intakes of 12, 9, and 6 g/d and collected all urine. The subjects' daily menus consisted of 27 279 individual servings, of which 83.0% were completely consumed, 16.5% completely rejected, and 0.5% incompletely consumed. Urinary recovery of dietary salt was 92% of recorded intake, indicating long-term steady-state sodium balance in both studies. Even at fixed salt intake, 24-hour urine collection for sodium excretion (UNaV) showed infradian rhythmicity. We defined a ±25 mmol deviation from the average difference between recorded sodium intake and UNaV as the prediction interval to accurately classify a 3-g difference in salt intake. Because of the biological variability in UNaV, only every other daily urine sample correctly classified a 3-g difference in salt intake (49%). By increasing the observations to 3 consecutive 24-hour collections and sodium intakes, classification accuracy improved to 75%. Collecting seven 24-hour urines and sodium intake samples improved classification accuracy to 92%. We conclude that single 24-hour urine collections at intakes ranging from 6 to 12 g salt per day were not suitable to detect a 3-g difference in individual salt intake. Repeated measurements of 24-hour UNaV improve precision. This knowledge could be relevant to patient care and the conduct of intervention trials.
准确收集的24小时尿液样本被认为可有效用于估算个体的盐摄入量。我们对10名男性进行了2项独立的超长期盐平衡研究，时长分别为105天（4名男性）和205天（6名男性），模拟火星飞行。我们在数月内将所有成分的饮食摄入量控制在每天12克、9克和6克的盐摄入量水平，并收集所有尿液。受试者的每日菜单包含27279份单独的食物，其中83.0%被完全食用，16.5%被完全拒绝，0.5%未被完全食用。饮食中盐的尿回收率为记录摄入量的92%，表明两项研究中均处于长期稳态钠平衡。即使在固定盐摄入量的情况下，24小时尿钠排泄量（UNaV）也显示出日内节律性。我们将记录的钠摄入量与UNaV之间平均差值的±25 mmol偏差定义为预测区间，以准确分类3克盐摄入量的差异。由于UNaV存在生物学变异性，只有每隔一天的尿液样本才能正确分类3克盐摄入量的差异（49%）。通过将观察次数增加到连续3次24小时收集和钠摄入量，分类准确率提高到75%。收集7次24小时尿液和钠摄入量样本可将分类准确率提高到92%。我们得出结论，每天摄入6至12克盐时，单次24小时尿液收集不适用于检测个体盐摄入量3克的差异。重复测量24小时UNaV可提高精度。这一知识可能与患者护理和干预试验的开展相关。
