Feasibility of outpatient electrolyte balance studies.

Abstract

Clinical studies requiring controlled electrolyte balance have traditionally been conducted in an inpatient (IP), metabolic ward setting. The purpose of this study was to test the feasibility of performing such studies in an outpatient (OP) clinical research setting. Focusing on sodium (Na) and potassium (K) balance, we retrospectively compared 28 subjects studied as OP vs 25 studied as IP on our metabolic ward. We assessed their adherence to our metabolic diets and their compliance with serial 24-hr urine collections. Dietary compliance was assessed by checksheet and urinary Na excretion; urine collection accuracy was determined by serial 24-hr creatinine excretion. The diets for both studies contained a low Na phase (10 mEq) and a high Na phase (200 mEq for IP and 250 mEq for OP), each lasting 1 week. When in balance on the low Na diet, 24-hr Na excretion was 4.6 +/- 0.7 mEq for OP and 13.4 +/- 2.2 mEq for IP, indicating excellent compliance with the low salt diet. Na excretion on the high Na diet was 184.5 +/- 7.4 mEq for OP and 195.3 +/- 9.6 mEq for IP. These values were not significantly different from each other; however, the OP were significantly less than their diet of 250 mEq Na (p less than 0.05). This difference may have been due to dermal Na losses. K excretion was also similar in the two groups. There was no significant difference in the reproducibility of individual multiple urinary creatinine measurements in OP vs IP.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Modest Caloric Restriction on Oxidative Stress in Women, a Randomized Trial

“…Energy and nutrient intake calculations were performed using the Nutrient Data System for Research (NDSR) software version 2009 developed by the Nutrition Coordinating Center, University of Minnesota, Minneapolis, MN, Food and Nutrient Database [20], [21]. Adherence to the protocol was monitored by urinary biomarkers (sodium, potassium, nitrogen) [22], [23].…”

Higher Neighborhood Population Density Is Associated with Lower Potassium Intake in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL)

“…The intra-class correlation coefficient (ICC) between blinded duplicate samples was 0.99, and the coefficient of variation was 4.1%. We converted biomarker potassium densities to milligrams/24 h for consistency with USDA recommendations [29], and applied a factor of 1.25 to excretion levels because about 80% of potassium intake is excreted in the urine [30][31][32][33]. In HCHS/SOL, 24-h potassium intake was assessed by the mean of two 24-h dietary recall (i.e., self-report) assessments [10].…”