Spot urine samples compared with 24-h urine samples for estimating changes in urinary sodium and potassium excretion in the China Salt Substitute and Stroke Study

Abstract. Introduction: Although difficult, the 24-hour urine sodium excretion is still considered as the gold standard method to estimate salt intake. The current study aimed to assess the validity of using spot urine samples in comparison with the standard 24-hour urine collection to estimate sodium and potassium intake in healthy Iranian adults. Methods and subjects: This cross-sectional study was performed on 1099 healthy Iranians aged 18–69 years. Samples of 24-hour and fasting morning spot urine were collected to measure sodium and potassium excretions. Tanaka’s formula was utilized to predict the 24-hour sodium and potassium urinary excretions based on the spot values. Results: The difference between measured and estimated sodium excretion values was 4265 mg/day (95% CI: 4106–4424; P < 0.001) and 2242 mg/day in case of potassium excretion (95% CI: 2140–2344; P < 0.001). There was a weak significant correlation between the 24-hour urine sodium and potassium excretion and the predicted values (intraclass correlations: 0.22 and 0.28, respectively; both P < 0.001). Conclusion: The weak association between the predicted and measured values of sodium and potassium along with the marked overestimation of daily sodium and potassium excretions based on the spot urine and using Tanaka formula indicates that Tanaka formula is not practical for the prediction of sodium and potassium or salt intake in Iranian adults. Using other spot urine sampling times and/or adopting a formula designed based on the characteristics of the Iranian population may increase the validity of spot urine tests.

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Validity of predictive equations for 24-h urinary potassium excretion based on timing of spot urine collection among adults: the MESA and CARDIA Urinary Sodium Study and NHANES Urinary Sodium Calibration Study

American Journal of Clinical Nutrition ◽

10.1093/ajcn/nqy138 ◽

2018 ◽

Vol 108 (3) ◽

pp. 532-547 ◽

Cited By ~ 8

Author(s):

Carla I Mercado ◽

Mary E Cogswell ◽

Catherine M Loria ◽

Kiang Liu ◽

Norrina Allen ◽

...

Keyword(s):

Prediction Equation ◽

Cross Sectional Study ◽

Urinary Sodium ◽

Urine Samples ◽

Potassium Excretion ◽

Urine Collection ◽

Cross Sectional ◽

Spot Urine ◽

Study Results ◽

Urinary Potassium

ABSTRACT Background 24-h urine collections are the suggested method to measure daily urinary potassium excretion (uK) but are costly and burdensome to implement. Objective This study tested how well existing equations with the use of spot urine samples can estimate 24-h uK and if accuracy varies by timing of spot urine collection, age, race, or sex. Design This cross-sectional study used data from 407 participants aged 18–39 y from the Washington, DC area in 2011 and 554 participants aged 45–79 y from Chicago in 2013. Spot urine samples were collected in individual containers for 24 h, and 1 for each timed period (morning, afternoon, evening, and overnight) was selected. For each selected timed spot urine, 24-h uK was predicted through the use of published equations. Difference (bias) between predicted and measured 24-h uK was calculated for each timed period and within age, race, and sex subgroups. Individual-level differences were assessed through the use of Bland-Altman plots and correlation tests. Results For all equations, regardless of the timing of spot urine, mean bias was usually significantly different than 0. No one prediction equation was unbiased across all sex, race, and age subgroups. With the use of the Kawasaki and Tanaka equations, 24-h uK was overestimated at low levels and underestimated at high levels, whereas observed differential bias with the Mage equation was in the opposite direction. Depending on prediction equation and timing of urine sample, 61–75% of individual 24-h uKs were misclassified among 500-mg incremental categories from <1500 to ≥3000 mg. Correlations between predicted and measured 24-h uK were poor to moderate (0.19–0.71). Conclusion Because predicted 24-h uK accuracy varies by timing of spot urine collection, published prediction equations, and within age-race-sex subgroups, study results making use of predicted 24-h uK in association with health outcomes should be interpreted with caution. It is possible that a more accurate prediction equation can be developed leading to different results.

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Estimation of Daily Sodium and Potassium Excretion Using Spot Urine and 24-Hour Urine Samples in a Black Population (Benin)

Journal of Clinical Hypertension ◽

10.1111/jch.12722 ◽

2015 ◽

Vol 18 (7) ◽

pp. 634-640 ◽

Cited By ~ 12

Author(s):

Carmelle Mizéhoun-Adissoda ◽

Corine Houehanou ◽

Thierry Chianéa ◽

François Dalmay ◽

André Bigot ◽

...

Keyword(s):

Black Population ◽

Urine Samples ◽

Potassium Excretion ◽

Spot Urine ◽

Sodium And Potassium

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Faculty Opinions recommendation of Urinary sodium and potassium excretion, mortality, and cardiovascular events.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.718530054.793499183 ◽

2014 ◽

Author(s):

Fredrik Palm

Keyword(s):

Cardiovascular Events ◽

Urinary Sodium ◽

Potassium Excretion ◽

Sodium And Potassium

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Association between 24-h urinary sodium and potassium excretion and blood pressure among Chinese adults aged 18–69 years

Scientific Reports ◽

10.1038/s41598-021-83049-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Xiaofu Du ◽

Le Fang ◽

Jianwei Xu ◽

Xiangyu Chen ◽

Yamin Bai ◽

...

Keyword(s):

Blood Pressure ◽

Sodium Excretion ◽

Sodium Intake ◽

Urinary Sodium Excretion ◽

Urinary Sodium ◽

Inverse Association ◽

Potassium Excretion ◽

Chinese Adults ◽

Potassium Intake ◽

Sodium And Potassium

AbstractThe direction and magnitude of the association between sodium and potassium excretion and blood pressure (BP) may differ depending on the characteristics of the study participant or the intake assessment method. Our objective was to assess the relationship between BP, hypertension and 24-h urinary sodium and potassium excretion among Chinese adults. A total of 1424 provincially representative Chinese residents aged 18 to 69 years participated in a cross-sectional survey in 2017 that included demographic data, physical measurements and 24-h urine collection. In this study, the average 24-h urinary sodium and potassium excretion and sodium-to-potassium ratio were 3811.4 mg/day, 1449.3 mg/day, and 4.9, respectively. After multivariable adjustment, each 1000 mg difference in 24-h urinary sodium excretion was significantly associated with systolic BP (0.64 mm Hg; 95% confidence interval [CI] 0.05–1.24) and diastolic BP (0.45 mm Hg; 95% CI 0.08–0.81), and each 1000 mg difference in 24-h urinary potassium excretion was inversely associated with systolic BP (− 3.07 mm Hg; 95% CI − 4.57 to − 1.57) and diastolic BP (− 0.94 mm Hg; 95% CI − 1.87 to − 0.02). The sodium-to-potassium ratio was significantly associated with systolic BP (0.78 mm Hg; 95% CI 0.42–1.13) and diastolic BP (0.31 mm Hg; 95% CI 0.10–0.53) per 1-unit increase. These associations were mainly driven by the hypertensive group. Those with a sodium intake above about 4900 mg/24 h or with a potassium intake below about 1000 mg/24 h had a higher risk of hypertension. At higher but not lower levels of 24-h urinary sodium excretion, potassium can better blunt the sodium-BP relationship. The adjusted odds ratios (ORs) of hypertension in the highest quartile compared with the lowest quartile of excretion were 0.54 (95% CI 0.35–0.84) for potassium and 1.71 (95% CI 1.16–2.51) for the sodium-to-potassium ratio, while the corresponding OR for sodium was not significant (OR, 1.28; 95% CI 0.83–1.98). Our results showed that the sodium intake was significantly associated with BP among hypertensive patients and the inverse association between potassium intake and BP was stronger and involved a larger fraction of the population, especially those with a potassium intake below 1000 mg/24 h should probably increase their potassium intake.

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