24-h Urinary Potassium Excretion Research Articles

Estimation of 24-hour urinary sodium and potassium excretion among Chinese adults: a cross-sectional study from the China National Nutrition Survey

BackgroundHigh-sodium intake is one of the most important risk factors for hypertension and cardiovascular disease, yet reliable national estimates of sodium intake in Chinese adults have not been reported. ObjectivesWe estimated 24-h urinary sodium and potassium excretion and population daily sodium and potassium intake of Chinese adults for the first time at a national level. MethodsA nationally representative cross-sectional survey was conducted to collect 24-h urine specimens from Chinese adults aged ≥18 y as part of the China National Nutrition Survey 2015. Finally, 10,114 participants (4932 males and 5182 females) with complete 24-h urine specimens were included in the analysis. Estimates of mean urinary electrolyte excretion and demographic, socioeconomic, and health characteristics were used with weighted coefficients that accounted for sample selection probabilities, poststratification weighting, and nonresponse rates. ResultsThe estimation of overall weighted mean 24-h urinary sodium excretion was 4121 mg (95% confidence interval [CI]: 3993, 4250), 4155 mg (95% CI: 3993, 4317) in males and 4081 mg (95% CI: 3953, 4209) in females (P for sex difference = 0.36). Overall mean 24-h urinary potassium excretion was 1534 mg (95% CI: 1492, 1577), 1468 mg (95% CI: 1424, 1513) in males and 1614 mg (95% CI: 1569–1660) in females (P for sex difference <0.001). Mean 24-h urinary sodium excretion was significantly higher in rural adults (4350 mg; 95% CI: 4217, 4483) than in urban residents (3909 mg; 95% CI: 3739, 4080; P < 0.001), and in northern residents (4388 mg; 95% CI: 4237, 4539) than in southern residents (3998 mg; 95% CI: 3832, 4163; P = 0.002). ConclusionsThe first nationwide survey with 24-h urine collection confirmed that mean sodium intake in Chinese adults was more than twice the upper limit, whereas mean potassium intake was <60% of the lower limit, recommended by the World Health Organization. Urgent measures should be taken to reduce sodium intake and increase potassium intake in China.

Awareness and Use of Low-Sodium Salt Substitutes and Its Impact on 24-h Urinary Sodium and Potassium Excretion in China-A Cross-Sectional Study.

The use of low-sodium salt substitute (LSSS) has the potential to reduce sodium and increase potassium intake. LSSS has been available in the Chinese market for years. However, its real-world use and impact on sodium/potassium intake is unclear. Baseline data of 4000 adult individuals who participated in three similarly designed randomized controlled trials were pooled together for this analysis. Self-reported awareness and use of LSSS were collected using a standardized questionnaire, and the participants' 24-h urinary sodium and potassium excretion was used to estimate their dietary intake. Mixed-effects models were developed to assess the relationship between LSSS and 24-h urinary sodium and potassium excretion. 32.0% of the participants reported awareness of LSSS and 11.7% reported its current use. After adjusting for location, sex, age, and education, compared with the group of participants unaware of LSSS, participants who were aware of but not using LSSS and those who were using LSSS had a lower 24-h urinary sodium excretion by -356.1 (95% CI: -503.9, -205.9) mg/d and -490.6 (95% CI: -679.2, -293.7) mg/d, respectively (p < 0.001). No significant difference was found for 24-h urinary potassium excretion or sodium-to-potassium ratio among the three groups (p > 0.05). In conclusion, the findings of low usage of LSSS and the reduced urinary sodium excretion associated with the awareness and use of LSSS provide further support for the prometon of LSSS as a key salt reduction strategy in China.

Low Potassium Intake: A Common Risk Factor for Nephrolithiasis in Patients with High Blood Pressure.

Hypertension (Htn) is a crucial cause of cardio-vascular and chronic kidney disease. Moreover, it is an independent risk factor for nephrolithiasis (NL). A diet rich in vegetables and fruits is indicated for both Htn and NL prevention, and the 24-h urinary potassium excretion can be used as a warning light for adherence. The aim of this study is to demonstrate the association between urinary potassium excretion and recurrent nephrolithiasis among patients affected by Htn. We have analyzed medical records of 119 patients affected by Htn and NL (SF-Hs) referring to Bone and Mineral Metabolism laboratory and 119 patients affected by Htn but without NL (nSF-Hs) referring to Hypertension and Organ Damage Hypertension related laboratory, both in Federico II University of Naples. The potassium 24-h urinary levels in SF-Hs were significantly lower compared to nSF-Hs. This difference was confirmed by the multivariable linear regression analysis in the unadjusted model and adjusted model for age, gender, metabolic syndrome, and body mass index. In conclusion, a higher potassium urinary excretion in 24-h is a protective factor against NL in patients affected by Htn and dietary interventions can be considered for kidney protection.

RAASi Therapy Attenuates the Association between 24-h Urinary Potassium Excretion and Dietary Potassium Intake in CKD Patients.

The aim of this study was to evaluate urinary potassium (K) excretion as a reliable marker of dietary K intake, in a cohort of CKD patients with or without Renin-Angiotensin-Aldosterone System (RAAS) inhibitor therapy. One hundred and thirty-eight consecutive out-patients (51 f and 87 m) aged 60 ± 13 years and affected by CKD stage 3-4, who were metabolically and nutritionally stable, entered the study between November 2021 and October 2022. No difference was observed between patients with (n = 85) or without (n = 53) RAAS inhibitor therapy, regarding dietary intakes, blood biochemistry, and 24-h urine excretion parameters. Considering all patients, urinary K showed a weak relationship with eGFR (r = 0.243, p < 0.01), and with dietary K intake (r = 0.184, p < 0.05). Serum K was not associated with dietary K intake, but an inverse relationship was observed with eGFR (r = -0.269, p < 0.01). When patients were examined depending on whether they were receiving RAAS inhibitor therapy, the weak inverse relationship between serum K and eGFR was maintained in both groups. Conversely, urinary K excretion remained positively associated with dietary K intake only in the no RAAS inhibitor group. In conclusion, 24-h urine K excretion may be used as a surrogate of K intake, but RAAS inhibitor therapy reduces the association between 24-h urine K excretion and dietary K intake in CKD patients.

Lower 24-h urinary potassium excretion is associated with higher prevalent depression and anxiety status in general population.

Uncertainty remains about the association of potassium (K) intake with depression and anxiety status. We explored their relationship using 24-h urinary K, reflecting K intake, in general population. We collected 24-h urine and performed self-rating depression and anxiety scales (SDS, SAS) cross-sectionally in adults selected by random sampling in China. SDS and SAS standard score ≥50 defined depression and anxiety status. Participants were divided into three groups (T1, T2, and T3) by 24-h urinary K tertile. Odds ratios (OR) and 95% confidence intervals were calculated. Sensitivity analysis was performed by excluding anti-hypertensive agent takers. 546 participants comprised current analytical sample. First, T1 and T2 groups showed higher SDS scores (40.0vs 40.0vs 36.0, p=.001), prevalence (19.8vs 15.9vs 7.1%, p=.002), whereas increased adjusted odds for depression status only in T1 group (OR=2.71, p=.017), compared with T3 group. Second, T1 and T2 groups showed higher SAS scores (38.0vs 40vs 35.0, p<.001) and prevalence (14.8vs 21.4vs 8.8%, p=.003), whereas increased adjusted odds for anxiety status only in T2 group (OR=2.07, p=.042), compared with T3 groups. Third, T1 and T2 groups showed higher prevalence (10.4%vs 11.5%vs 2.7%, p=.004) and adjusted odds (OR=3.71, p=.013; OR=3.66, p=.014) for co-existent anxiety and depression status, compared with T3 group. Most results remained consistent in sensitivity analysis. Lower K intake is implicated in presence of anxiety and depression status in general population; this may provide basis for programs to increase K intake and prevent disease.

Low Urinary Potassium Excretion Is Associated with Higher Risk of All-Cause Mortality in Patients with Type 2 Diabetes: Results of the Dutch Diabetes and Lifestyle Cohort Twente (DIALECT)

Low 24-h urinary potassium excretion, reflecting low potassium intake, is associated with premature mortality in the general population. To determine whether urinary potassium excretion is associated with all-cause mortality in patients with type 2 diabetes. We performed a prospective cohort study in 654 patients with type 2 diabetes in the Diabetes and Lifestyle Cohort Twente (DIALECT). Sex-specific tertiles of 24-h urinary potassium excretion were analyzed in a multivariable Cox regression model with all-cause mortality. The outpatient program of the hospital uses a continuous surveillance system by the municipal registry of death to ensure up-to-date information on the patient's status (alive or deceased). FFQs were used to study associations between urinary potassium excretion and food products. Urinary potassium excretion at baseline was 84 ± 25 mmol/d in males and 65 ± 22 mmol/d in females, corresponding to estimated potassium intakes of 4250 ± 1270 mg/d and 3300 ± 875 mg/d. During a median follow-up of 5.2 (IQR: 2.7-7.9] y, 96 participants died. In a fully adjusted model, patients in the lowest sex-specific tertile had a higher risk of all-cause mortality, compared with patients in the highest sex-specific tertile (HR: 2.09; 95% CI: 1.06, 4.10; P = 0.03). Patients in the lowest sex-specific tertile consumed fewer fruits and vegetables, dairy, coffee, and potato products compared with patients in the highest sex-specific tertile (all P < 0.05). Low potassium intake is associated with a higher risk of all-cause mortality in Dutch patients with type 2 diabetes. Intervention studies are needed to determine whether potassium supplementation improves longevity in patients with type 2 diabetes. This trial was registered in the Dutch Trial Register as NTR trial code 5855.

Prediction Tool to Estimate Potassium Diet in Chronic Kidney Disease Patients Developed Using a Machine Learning Tool: The UniverSel Study.

There is a need for a reliable and validated method to estimate dietary potassium intake in chronic kidney disease (CKD) patients to improve prevention of cardiovascular complications. This study aimed to develop a clinical tool to estimate potassium intake using 24-h urinary potassium excretion as a surrogate of dietary potassium intake in this high-risk population. Data of 375 adult CKD-patients routinely collecting their 24-h urine were included to develop a prediction tool to estimate potassium diet. The prediction tool was built from a random sample of 80% of patients and validated on the remaining 20%. The accuracy of the prediction tool to classify potassium diet in the three classes of potassium excretion was 74%. Surprisingly, the variables related to potassium consumption were more related to clinical characteristics and renal pathology than to the potassium content of the ingested food. Artificial intelligence allowed to develop an easy-to-use tool for estimating patients’ diets in clinical practice. After external validation, this tool could be extended to all CKD-patients for a better clinical and therapeutic management for the prevention of cardiovascular complications.

Urinary Potassium Excretion, Fibroblast Growth Factor 23, and Incident Hypertension in the General Population-Based PREVEND Cohort

High plasma fibroblast growth factor 23 (FGF23) and low potassium intake have each been associated with incident hypertension. We recently demonstrated that potassium supplementation reduces FGF23 levels in pre-hypertensive individuals. The aim of the current study was to address whether 24-h urinary potassium excretion, reflecting dietary potassium intake, is associated with FGF23, and whether FGF23 mediates the association between urinary potassium excretion and incident hypertension in the general population. At baseline, 4194 community-dwelling individuals without hypertension were included. Mean urinary potassium excretion was 76 (23) mmol/24 h in men, and 64 (20) mmol/24 h in women. Plasma C-terminal FGF23 was 64.5 (54.2–77.8) RU/mL in men, and 70.3 (56.5–89.5) RU/mL in women. Urinary potassium excretion was inversely associated with FGF23, independent of age, sex, urinary sodium excretion, bone and mineral parameters, inflammation, and iron status (St. β −0.02, p < 0.05). The lowest sex-specific urinary potassium excretion tertile (HR 1.18 (95% CI 1.01–1.37)), and the highest sex-specific tertile of FGF23 (HR 1.17 (95% CI 1.01–1.37)) were each associated with incident hypertension, compared with the reference tertile. FGF23 did not mediate the association between urinary potassium excretion and incident hypertension. Increasing potassium intake, and reducing plasma FGF23 could be independent targets to reduce the risk of hypertension in the general population.

Accuracy of equations for predicting 24-h urinary potassium excretion from spot urine samples in Chinese children.

Accurate assessments of potassium intake in children are important for the early prevention of CVD. Currently, there is no simple approach for accurate estimation of potassium intake in children. We aim to evaluate the accuracy of 24-h urinary potassium excretion (24UKV) estimation in children using three common equations: the Kawasaki, Tanaka and Mage formulas, in a hospital-based setting. A total of 151 participants aged 5-18 years were initially enrolled, and spot urine samples were collected in the whole 24-h duration to measure the concentrations of potassium and creatinine. We calculated the mean difference, absolute and relative difference and misclassification rate between measured 24UKV and the predicted ones using Kawasaki, Tanaka and Mage formulas in 129 participants. The mean measured 24UKV was 1193·3 mg/d in our study. Mean differences between estimated and measured 24UKV were 1215·6, -14·9 and 230·3 mg/d by the Kawasaki, Tanaka and Mage formulas, respectively. All estimated 24UKV were significantly different from the measured values in all the time point (all P < 0·05), except for the predicted values from Tanaka formula using morning, afternoon and evening spot urine. The proportions with relative differences over 40 % were 87·2%, 32·5% and 47·3 % for Kawasaki, Tanaka and Mage formulas, respectively. Misclassification rates were 91·5 % for Kawasaki, 44·4 % for Tanaka and 58·9 % for Mage formula at the individual level. Our findings showed that misclassification could occur on the individual level when using Kawasaki, Tanaka and Mage formulas to estimate 24UKV from spot urine in the child population.

Lower 24-h urinary potassium excretion is negatively associated with excessive daytime sleepiness in thegeneral population.

Uncertainty remains about the association of potassium (K) intake and sleepiness. Therefore, we aimed to explore the relationship between K excretion using 24-h urine samples and excessive daytime sleepiness (EDS) in the general population. In a cross-sectional study, we used multi-stage proportional random sampling to obtain a study sample aged ≥ 18years from Emin, China between March and June 2019. We collected timed 24-h urine specimens and conducted EDS assessments using the Epworth Sleepiness Scale (ESS) questionnaire. Subjects were divided into two groups by the median of 24-h urinary potassium (24-h UK). EDS was defined as ESS score ≥ 10. Multi-variable linear regression was used to examine the association between the 24-h UK and the odds of prevalent EDS. We performed a sensitivity analysis by excluding subjects under anti-hypertensive treatment and those with sleep disordered breathing by the NoSAS scale. A total of 470 participants with complete 24-h urine samples and ESS data (62% women, mean age 49.6years, mean ESS score of 9.0 ± 5.2) were enrolled. The mean ESS score was significantly lower in the upper half of 24-h UK group than in the lower half (9.5 ± 5.3 vs 8.5 ± 5.1, P = 0.044), and accordingly, prevalent EDS was significantly greater in the lower half than in the higher half (49% vs 40%, P = 0.039). In further improving the propensity matching score, the results remained consistent with the overall results. In multiple linear regression, 24-h UK was negatively correlated with ESS score (β = - 0.180 (- 0.276, - 0.085), < 0.001). Sensitivity analysis demonstrated augmented results in those without anti-hypertensive treatment. Lower potassium intake, as suggested by lower UK excretion, may be implicated in the presence of EDS in the general population.

Effects of a reduced-sodium added-potassium salt substitute on blood pressure in rural Indian hypertensive patients: a randomized, double-blind, controlled trial

High salt intake is a major modifiable risk factor of hypertension which is prevalent in India. It is not yet clear if salt substitutes reduce blood pressure (BP) among Indian hypertensive patients. Examine the acceptability, usage, and BP effects of a reduced-sodium and added-potassium salt substitute among hypertensive patients. We enrolled 502 participants with hypertension (aged 61.6±12.0 y, 58.8% women) from 7 villages in rural India. Participants were randomly assigned to receive either regular salt (100% sodium chloride) or the salt substitute (70% sodium chloride/30% potassium chloride blend), and advised to replace all home salt use. The primary outcome was the change in systolic BP (SBP) from baseline to 3 mo comparing the salt substitute and regular salt groups. Secondary outcomes included the change in diastolic BP (DBP), 24-h urinary biomarkers, and self-reported use and satisfaction with the study salt provided. A total of 494 (98%) participants completed 1 mo and 476 (95%) participants completed the 3-mo follow-up. At 3 mo, the salt substitute intervention significantly decreased the average SBP by 4.6 mmHg (95% CI: 3.0, 6.2, P< 0.001) and DBP by 1.1 mmHg (95% CI: 0.2, 2.1 mmHg, P=0.02). There was a significant increase in 24-h urinary potassium excretion in the salt substitute group by 0.24 g/d (95% CI: 0.12, 0.35 g/d, P< 0.001) and a decrease in the urinary sodium to potassium ratio by 0.71 (95% CI: 0.55, 0.87, P< 0.0001) compared with the control group. Participants reported that they used the study salt nearly every day of the week (mean±SD, 6.3±1.8 d) and rated the taste of the study salts similarly. The reduced-sodium added-potassium salt led to a substantial reduction in SBP in hypertensive patients, supporting salt substitution as an effective, low-cost intervention for BP lowering in rural India. This trial was registered at clinicaltrials.gov as NCT03909659.

Low potassium intake and its association with blood pressure among adults in Malaysia: findings from the MyCoSS (Malaysian Community Salt Survey)

BackgroundHigh blood pressure or hypertension is well recognized as an important modifiable risk factor for cardiovascular diseases. Several studies had indicated potassium intake has a blood pressure lowering effect. This study aimed to estimate potassium intake via 24-h urinary potassium excretion and to determine the association between potassium intake and blood pressure among adults in Malaysia.MethodsData for 424 respondents in this study were drawn from MyCoSS, a nationwide cross- sectional study conducted among Malaysians who were 18 years and above. Respondents were recruited using stratified cluster sampling, covering urban and rural areas in each state in Malaysia. Data collection was undertaken from October 2017 until March 2018. A single urine sample was collected over 24 h for quantification of potassium excreted. Information on socio-demography and medical history of the respondents were collected by interviewer-administered questionnaires. Anthropometric measurements were measured using validated equipment. BMI was estimated using measured body weight and height. Digital blood pressure monitor (Omron HBP-1300) was used to measure blood pressure. Descriptive statistics, analysis of variance (ANOVA), and multivariable linear regression were used to analyze the data in SPSS Version 21.ResultsMean 24-h urinary potassium excretion for the 424 respondents was 37 mmol (95% CI 36, 38). Gender and ethnicity showed statistically significant associations with 24-h urinary potassium excretion. However, potassium excretion was not significantly associated with blood pressure in this study.ConclusionPotassium intake is very low among the adults in Malaysia. Therefore, further education and promotional campaigns regarding daily consumption of potassium-rich diet and its benefits to health need to be tailored for the Malaysian adult population.

The impact of baseline potassium intake on the dose-response relation between sodium reduction and blood pressure change: systematic review and meta-analysis of randomized trials.

Sodium and potassium appear to interact with each other in their effects on blood pressure with potassium supplementation having a greater blood pressure lowering-effect when sodium intake is high. Whether the effect of sodium reduction on blood pressure varies according to potassium intake levels is unclear. We carried out a systematic review and meta-analysis to examine the impact of baseline potassium intake on blood pressure response to sodium reduction in randomized trials in adult populations, with sodium and potassium intake estimated from 24-h urine samples. We included 68 studies involving 5708 participants and conducted univariable and multivariable meta-regression. The median intake of baseline potassium was 67.7 mmol (Interquartile range: 54.6-76.4 mmol), and the mean reduction in sodium intake was 128 mmol (95% CI: 107-148). Multivariable meta-regression that included baseline 24-h urinary potassium excretion, age, ethnicity, baseline blood pressure, change in 24-h urinary sodium excretion, as well as the interaction between baseline 24-h urinary potassium excretion and change in 24-h urinary sodium excretion did not identify a significant association of baseline potassium intake levels with the blood pressure reduction achieved with a 50 mmol lowering of sodium intake (p > 0.05 for both systolic and diastolic blood pressure). A higher starting level of blood pressure was consistently associated with a greater blood pressure reduction from reduced sodium consumption. However, the nonsignificant findings may subject to the limitations of the data available. Additional studies with more varied potassium intake levels would allow a more confident exclusion of an interaction.

Association between 24-h urinary sodium and potassium excretion and blood pressure among Chinese adults aged 18\u201369\xa0years

The 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.

Diminished antiproteinuric effect of the angiotensin receptor blocker losartan during high potassium intake in patients with CKD.

BackgroundAngiotensin II type 1 receptor blockers (ARBs) lower blood pressure (BP) and proteinuria and reduce renal disease progression in many—but not all—patients. Reduction of dietary sodium intake improves these effects of ARBs. Dietary potassium intake affects BP and proteinuria. We set out to address the effect of potassium intake on BP and proteinuria response to losartan in non-diabetic proteinuric chronic kidney disease (CKD) patients. MethodsWe performed a post hoc analysis of a placebo-controlled interventional cross-over study in 33 non-diabetic proteinuric patients (baseline mean arterial pressure and proteinuria: 105 mmHg and 3.8 g/day, respectively). Patients were treated for 6 weeks with placebo, losartan and losartan/hydrochlorothiazide (HCT), combined with a habitual (∼200 mmol/day) and low-sodium (LS) diet (<100 mmol/day), in randomized order. To analyse the effects of potassium intake, we categorized patients based on median split of 24-h urinary potassium excretion, reflecting potassium intake.ResultsMean potassium intake was stable during all six treatment periods. Losartan and losartan/HCT lowered BP and proteinuria in all treatment groups. Patients with high potassium intake showed no difference in the BP effects compared with patients with low potassium intake. The antiproteinuric response to losartan monotherapy and losartan combined with HCT during the habitual sodium diet was significantly diminished in patients with high potassium intake (20% versus 41%, P = 0.011; and 48% versus 64%, P = 0.036). These differences in antiproteinuric response abolished when shifting to the LS diet.ConclusionsIn proteinuric CKD patients, the proteinuria, but not BP-lowering response to losartan during a habitual high-sodium diet was hampered during high potassium intake. Differences disappeared after sodium status change by LS diet.

Sodium and potassium intakes in the Kazakhstan population estimated using 24-h urinary excretion: evidence for national action.

There is strong scientific evidence for reducing sodium and increasing potassium intake to the recommended levels to lower blood pressure and cardiovascular risk, but consumption levels in Kazakhstan are unknown. This study sought to estimate mean sodium and potassium intake using 24-h urine samples and describe dietary knowledge and behavior among adults in Kazakhstan. In two cross-sectional surveys, the same multi-stage cluster sampling method was used to randomly select participants aged 25-64years from Almaty City in 2015 and Kyzylorda in 2016. Complete 24-h urine samples were available for 478 participants; 294 in Almaty City and 184 in Kyzylorda (response rates 86% and 54%, respectively) and were weighted for the age and sex distribution of the two regions. Weighted mean 24-h urinary sodium excretion was 6782mg/day (17.2g salt) (95% CI 6507-7058) in both regions combined, and not significantly different between the regions (P = 0.660). 99% of adults in the two regions combined consumed above the World Health Organization's (WHO) recommended sodium maximum of 2000mg/day; however, only 15% of adults perceived that they consumed excess sodium. Weighted mean 24-h urinary potassium excretion was 2271mg/day (95% CI 2151-2391) for the regions combined. Mean sodium consumption in Kazakhstan was more than triple the WHO's recommended maximum, and mean potassium consumption was below the recommended minimum. National efforts to lower sodium intake and increase potassium intake are needed and would likely prevent ample premature deaths and disease burden.

Population biomonitoring of micronutrient intakes in children using urinary spot samples.

Urinary spot samples are a promising method for the biomonitoring of micronutrient intake in children. Our aim was to assess whether urinary spot samples could be used to estimate the 24-h urinary excretion of potassium, phosphate, and iodine at the population level. A cross-sectional study of 101 children between 6 and 16years of age was conducted. Each child collected a 24-h urine collection and three urinary spot samples (evening, overnight, and morning). Several equations were used to estimate 24-h excretion based on the urinary concentrations of each micronutrient in the three spot samples. Various equations and spot combinations were compared using several statistics and plots. Ninety-four children were included in the analysis (mean age: 10.5years). The mean measured 24-h urinary excretions of potassium, phosphate, and iodine were 1.76g, 0.61g, and 95µg, respectively. For potassium, the best 24-h estimates were obtained with the Mage equation and morning spot (mean bias: 0.2g, correlation: 0.27, precision: 56%, and misclassification: 10%). For phosphate, the best 24-h estimates were obtained with the Mage equation and overnight spot (mean bias: -0.03g, correlation: 0.54, precision: 72%, and misclassification: 10%). For iodine, the best 24-h estimates were obtained with the Remer equation and overnight spot (mean bias: -8µg, correlation: 0.58, precision: 86%, misclassification: 16%). Urinary spot samples could be a good alternative to 24-h urine collection for the population biomonitoring of iodine and phosphate intakes in children. For potassium, spot samples were less reliable.

A Body Mass Index-Based Cross-Classification Approach for the Assessment of Prognostic Factors in Chronic Kidney Disease Progression

Background/Aims: Cross-classification analyses are rarely reported. We investigated the prognostic factors for chronic kidney disease (CKD) progression using a body mass index (BMI)-based cross-classification approach. Methods: Patients’ renal outcome (≥50% decline in the estimated glomerular filtration rate or end-stage renal disease) in each subcohort was examined. Results: The number of prognostic factors identified in the multivariate Cox analysis was smaller in the “BMI ≥25, female” and CKD stage 3 subcohorts than in other subcohorts. Prognostic factors identified in the “BMI ≥25, CKD stage 3” subcohort only comprised albuminuria and male sex, and those in the “BMI ≥25, female” subcohort only comprised albuminuria, hyperphosphatemia, and anemia. Albuminuria, kidney impairment, male sex, hyperphosphatemia, anemia, and increased pulse pressure × heart rate product (PP × HR; pulsatile stress) were stable renal prognostic factors in almost all subcohorts. On the other hand, the prognostic value of increased BMI, younger age, hypoalbuminemia, increased intact parathyroid hormone, and decreased estimated 24-h urinary potassium excretion (e24hUK) differed according to subcohort. BMI was positively associated with CKD progression in the “BMI ≥25, age ≥65 years” and “BMI ≥25, CKD stages 4–5” subcohorts, whereas it was negatively associated with CKD progression in the “BMI <25, diabetes mellitus” subcohort. PP × HR was independently associated with CKD progression in the “BMI <25, CKD stage 3” subcohort, which had relatively few identified renal prognostic factors. Decreased e24hUK was a renal prognostic factor for CKD progression in the “BMI <25, CKD stages 4–5” subcohort, while no significant factors were observed in the “BMI ≥25, CKD stages 4–5” subcohort. Conclusion: A BMI-based cross-classification approach, which provides more comprehensive findings than that in previous approaches, is expected to be an effective method for evaluating renal prognostic factors in patients with CKD who are affected by multiple risk factors.

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

24-h urine collections are the suggested method to measure daily urinary potassium excretion (uK) but are costly and burdensome to implement. 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. 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. 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). 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.

Revised Reference Values for Potassium Intake

Background: The nutrition societies of Germany, Austria and Switzerland have revised the reference values for potassium intake in January 2017. Methods: For adults, the estimated value was based on the 24-h urinary potassium excretion and on preventive considerations regarding hypertension and stroke. The estimated values for children and adolescents were extrapolated from the adult estimated value considering differences in body mass. For infants aged 0 to under 4 months, the estimated value was set based on the potassium intake via breast milk. From this reference value, the estimated value for infants aged 4 to under 12 months was also derived by extrapolation. The estimated value for lactating women takes into account the potassium loss via breast milk. Results: The estimated values for potassium intake are set at 400 mg/day for breastfed infants aged 0 to under 4 months, 600 mg/day for infants aged 4 to under 12 months, 1,100-4,000 mg/day for children and adolescents, 4,000 mg/day for adults and pregnant women and 4,400 mg/day for lactating women. Conclusions: The consumption of potassium-rich foods should be generally increased. Supplemental intake beyond the estimated values has no health benefit and is therefore not recommended.