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Agreement between 24-hour salt ingestion and sodium excretion in a controlled environment

Item Type:Article
Title:Agreement between 24-hour salt ingestion and sodium excretion in a controlled environment
Creators Name:Lerchl, K. and Rakova, N. and Dahlmann, A. and Rauh, M. and Goller, U. and Basner, M. and Dinges, D.F. and Beck, L. and Agureev, A. and Larina, I. and Baranov, V. and Morukov, B. and Eckardt, K.U. and Vassilieva, G. and Wabel, P. and Vienken, J. and Kirsch, K. and Johannes, B. and Krannich, A. and Luft, F.C. and Titze, J.
Abstract: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.
Keywords:Hypertension, Salt, Sodium, Sodium, Dietary, Urine Specimen Collection
Publisher:American Heart Association
Page Range:850-857
Date:October 2015
Official Publication:https://doi.org/10.1161/HYPERTENSIONAHA.115.05851
PubMed:View item in PubMed

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