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

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Item Type:	Article
Title:	Agreement between 24-hour salt ingestion and sodium excretion in a controlled environment
Creators Name:	Lerchl, K., Rakova, N., Dahlmann, A., Rauh, M., Goller, U., Basner, M., Dinges, D.F., Beck, L., Agureev, A., Larina, I., Baranov, V., Morukov, B., Eckardt, K.U., Vassilieva, G., Wabel, P., Vienken, J., Kirsch, K., Johannes, B., Krannich, A., 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
Source:	Hypertension
ISSN:	0194-911X
Publisher:	American Heart Association
Volume:	66
Number:	4
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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