Overnight urine collections to estimate sodium intake.

Abstract

SUMMARY This study was undertaken to formulate reliable confidence limits for the relationship between nocturnal and 24-hour urine sodium (Na) excretion for use in population compliance studies. Urine excretions were measured in 12 white and 12 black men at three levels of sodium (Na) intake (10, 200, and 400 mEq/day) for 7 days. Nocturnal Na, chloride (Cl), and Cl determined by titrator stick were all highly correlated (r2= 0.86, p < 0.001) with 24-hour U N .V. No significant difference could be attributed to race. Discriminate analysis revealed that the subjects could be categorized with respect to Na intake with accuracies of 95%, 90%, and 85% (low, middle, and high Na intake respectively) by means of two nocturnal urine Cl titrator stick measurements. In addition, two such measurements showing nocturnal U a V < 10 mEq indicated with 95% accuracy that 24-hour U Nl V was < 60 mEq. According to these data, measurement of nocturnal Na or Cl excretion is a useful means of assessing compliance to a low sodium intake, and the titrator sticks are a convenient and inexpensive tool. (Hypertension 4:494-498, 1982) KEY WORDS • sodium • chloride • hypertension • diurnal rhythms • nutrition T HE hypothesis that habitual high-sodium intake is a contributing factor in the development of arterial hypertension was first proposed in the Nei Ching,' a Chinese text that is the oldest known collection of medical writings. Since that time the hypothesis has been inferred from numerous epidemiological, clinical, and experimental animal studies.2 " 13However, in testing the hypothesis, it has been difficult to estimate individual sodium consumption; collection of multiple 24-hour urine specimens, use of dietary recall, and analysis of duplicate diets have been unsatisfactory research tools.To find a precise method for estimating sodium intake, we first investigated whether the relationship between nocturnal and 24-hour sodium excretion might be different in whites and blacks. In addition, we evaluated simple means to assess compliance that could be used in the home as well as in the laboratory, and provide reliable confidence limits. MethodsWe recruited 12 white and 12 black men ranging in age from 19 to 32 years. They were either students at

Self-monitoring of home blood pressure with estimation of daily salt intake using a new electrical device

“…Additional contributors would be inter-individual differences in renal function, interval between dinnertime and bedtime, antidiurenic hormone (ADH) function and in sweating. Some studies have demonstrated good correlations between overnight urinary salt and 24-h urinary salt, [18][19][20] whereas others found an absence of correlation 28,29 and some suggest seven or 14 measurements are needed to replace 24-h urine collection. 19,30 Urinary salt excretion is affected not only by the previous day's salt intake, but also by the salt intake of the previous 3 or 4 days.…”

“…18-20 K Salt titrator sticks and tapes are known as simple method to detect the concentration of salt in overnight urine. 18,21 K Sensitivity and resistance to the effects of sodium were evaluated by the degree of BP change between high-salt diet and low-salt diet. [22][23][24] What this study adds K A new simple method to monitor daily salt intake was developed.…”

“…A 24-h sodium excretion (Na 24 ) value can also be estimated from overnight urinary sodium excretion (UNa n ). [18][19][20] We consider it ideal to measure salt intake at home in order to control average daily salt intake. Salt titrator sticks 18 and tapes 21 that detect chlorine ion are easy to use, but they are not accurate depending on the amount of urine applied to the tape and error in visual perception of colour change.…”

“…[18][19][20] We consider it ideal to measure salt intake at home in order to control average daily salt intake. Salt titrator sticks 18 and tapes 21 that detect chlorine ion are easy to use, but they are not accurate depending on the amount of urine applied to the tape and error in visual perception of colour change. To calculate overnight urinary sodium excretion, it is necessary to check urine volume and integrate it into sodium concentration.…”

Blood pressure and diurnal variation in sodium, potassium, and water excretion

“…The ratio of mean 24-h to mean overnight excretion of sodium observed in HCP hypertensives was also lower than similar ratios derived from published data for young adults, normotensives, and borderline hypertensives. [53][54][55][56][57][58] Given the ages of HCP participants (41-80 years), it was not clear whether the observed reversal of diurnal patterns of sodium and water excretion was associated with hypertension per se, or reflected decline of renal functional capacity with age, since age appears to modify factors which determine renal sodium handling, including glomerular filtration rate and renal haemodynamics. 59 Furthermore, in one study, persons over age 40 had a lower ratio of mean 24-h to mean overnight excretion of sodium than persons under 40.…”