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The potential role of the eGFR in differentiating between true and pseudohyperkalaemia.
Morris, TG, Lamba, S, Fitzgerald, T, Roulston, G, Johnstone, H, Mirzazadeh, M
Annals of clinical biochemistry. 2020;(6):444-455
Abstract
BACKGROUND Differentiating between true and pseudohyperkalaemia is essential for patient management. The common causes of pseudohyperkalaemia include haemolysis, blood cell dyscrasias and EDTA contamination. One approach to differentiate between them is by checking the renal function, as it is believed that true hyperkalaemia is rare with normal function. This is logical, but there is limited published evidence to support it. The aim of this study was to investigate the potential role of the estimated glomerular filtration rate in differentiating true from pseudohyperkalaemia. METHODS GP serum potassium results >6.0 mmol/L from 1 January 2017 to 31 December 2017, with a repeat within seven days, were included. Entries were retrospectively classified as true or pseudohyperkalaemia based on the potassium reference change value and reference interval. If the initial sample had a full blood count, it was classified as normal/abnormal to remove blood cell dyscrasias. Different estimated glomerular filtration rate cut-points were used to determine the potential in differentiating true from pseudohyperkalaemia. RESULTS A total of 272 patients were included with potassium results >6.0 mmol/L, with 145 classified as pseudohyperkalaemia. At an estimated glomerular filtration rate of 90 ml/min/1.73 m2, the negative predictive value was 81% (95% CI: 67-90%); this increased to 86% (95% CI: 66-95%) by removing patients with abnormal full blood counts. When only patients with an initial potassium ≥6.5 mmol/L were included (regardless of full blood count), at an estimated glomerular filtration rate of 90 ml/min/1.73 m2, the negative predictive value was 100%. Lower negative predictive values were seen with decreasing estimated glomerular filtration rate cut-points. CONCLUSION Normal renal function was not associated with true hyperkalaemia, making the estimated glomerular filtration rate a useful tool in predicting true from pseudohyperkalaemia, especially for potassium results ≥6.5 mmol/L.
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Emerging concepts of potassium homeostasis in plants.
Srivastava, AK, Shankar, A, Nalini Chandran, AK, Sharma, M, Jung, KH, Suprasanna, P, Pandey, GK
Journal of experimental botany. 2020;(2):608-619
Abstract
Potassium (K+) is an essential cation in all organisms that influences crop production and ecosystem stability. Although most soils are rich in K minerals, relatively little K+ is present in forms that are available to plants. Moreover, leaching and run-off from the upper soil layers contribute to K+ deficiencies in agricultural soils. Hence, the demand for K fertilizer is increasing worldwide. K+ regulates multiple processes in cells and organs, with K+ deficiency resulting in decreased plant growth and productivity. Here, we discuss the complexity of the reactive oxygen species-calcium-hormone signalling network that is responsible for the sensing of K+ deficiency in plants, together with genetic approaches using K+ transporters that have been used to increase K+ use efficiency (KUE) in plants, particularly under environmental stress conditions such as salinity and heavy metal contamination. Publicly available rice transcriptome data are used to demonstrate the two-way relationship between K+ and nitrogen nutrition, highlighting how each nutrient can regulate the uptake and root to shoot translocation of the other. Future research directions are discussed in terms of this relationship, as well as prospects for molecular approaches for the generation of improved varieties and the implementation of new agronomic practices. An increased knowledge of the systems that sense and take up K+, and their regulation, will not only improve current understanding of plant K+ homeostasis but also facilitate new research and the implementation of measures to improve plant KUE for sustainable food production.
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Interim effects of salt substitution on urinary electrolytes and blood pressure in the China Salt Substitute and Stroke Study (SSaSS).
Huang, L, Tian, M, Yu, J, Li, Q, Liu, Y, Yin, X, Wu, JH, Marklund, M, Wu, Y, Li, N, et al
American heart journal. 2020;:136-145
Abstract
The Salt Substitute and Stroke Study is an ongoing 5-year large-scale cluster randomized trial investigating the effects of potassium-enriched salt substitute compared to usual salt on the risk of stroke. The study involves 600 villages and 20,996 individuals in rural China. Intermediate risk markers were measured in a random subsample of villages every 12 months over 3 years to track progress against key assumptions underlying study design. Measures of 24-hour urinary sodium, 24-hour urinary potassium, blood pressure and participants' use of salt substitute were recorded, with differences between intervention and control groups estimated using generalized linear mixed models. The primary outcome of annual event rate in the two groups combined was determined by dividing confirmed fatal and non-fatal strokes by total follow-up time in the first 2 years. The mean differences (95% CI) were -0.32 g (-0.68 to 0.05) for 24-hour urinary sodium, +0.77 g (+0.60 to +0.93) for 24-hour urinary potassium, -2.65 mmHg (-4.32 to -0.97) for systolic blood pressure and +0.30 mmHg (-0.72 to +1.32) for diastolic blood pressure. Use of salt substitute was reported by 97.5% in the intervention group versus 4.2% in the control group (P<.0001). The overall estimated annual event rate for fatal and non-fatal stroke was 3.2%. The systolic blood pressure difference and the annual stroke rate were both in line with the statistical assumptions underlying study design. The trial should be well placed to address the primary hypothesis at completion of follow-up.
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Associations of 24-Hour Urinary Sodium and Potassium Excretion with Cardiac Biomarkers: The Maastricht Study.
Martens, RJH, Henry, RMA, Bekers, O, Dagnelie, PC, van Dongen, MCJM, Eussen, SJPM, van Greevenbroek, M, Kroon, AA, Stehouwer, CDA, Wesselius, A, et al
The Journal of nutrition. 2020;(6):1413-1424
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Abstract
BACKGROUND It is a matter of debate whether sodium and potassium intake are associated with heart disease. Further, the mechanisms underlying associations of sodium and potassium intake with cardiac events, if any, are not fully understood. OBJECTIVES We examined cross-sectional associations of 24-h urinary sodium excretion (UNaE) and potassium excretion (UKE), as estimates of their intakes, with high-sensitivity cardiac troponins T (hs-cTnT) and I (hs-cTnI), and N-terminal pro-B-type natriuretic peptide (NT-proBNP), which are markers of cardiomyocyte injury and cardiac dysfunction. METHODS We included 2961 participants from the population-based Maastricht Study (mean ± SD age 59.8 ± 8.2 y, 51.9% men), who completed the baseline survey between November 2010 and September 2013. Associations were examined with restricted cubic spline linear regression analyses and ordinary linear regression analyses, adjusted for demographics, lifestyle, and cardiovascular disease (CVD) risk factors. RESULTS Median [IQR] 24-h UNaE and UKE were 3.7 [2.8-4.7] g/24 h and 3.0 [2.4-3.6] g/24 h, respectively. After adjustment for potential confounders, 24-h UNaE was not associated with hs-cTnT, hs-cTnI, and NT-proBNP concentrations. In contrast, after adjustment for potential confounders, lower 24-h UKE was nonlinearly associated with higher hs-cTnT and NT-proBNP. For example, as compared with the third/median quintile of 24-h UKE (range: 2.8-3.2 g/24 h), participants in the first quintile (range: 0.5-2.3 g/24 h) had 1.05 (95% CI: 0.99, 1.11) times higher hs-cTnT and 1.14 (95% CI: 1.03, 1.26) times higher NT-proBNP. Associations were similar after further adjustment for estimated glomerular filtration rate, albuminuria, blood pressure, and serum potassium. CONCLUSIONS Twenty-four-hour UNaE was not associated with the studied cardiac biomarkers. In contrast, lower 24-h UKE was nonlinearly associated with higher hs-cTnT and NT-proBNP. This finding supports recommendations to increase potassium intake in the general population. In addition, it suggests that cardiac dysfunction and/or cardiomyocyte injury may underlie previously reported associations of lower potassium intake with CVD mortality.
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Serum potassium level on hospital arrival and survival after out-of-hospital cardiac arrest: The CRITICAL study in Osaka, Japan.
Shida, H, Matsuyama, T, Iwami, T, Okabayashi, S, Yamada, T, Hayakawa, K, Yoshiya, K, Irisawa, T, Noguchi, K, Nishimura, T, et al
European heart journal. Acute cardiovascular care. 2020;(4_suppl):S175-S183
Abstract
BACKGROUND Little is known about the association between serum potassium level on hospital arrival and neurological outcome after out-of-hospital cardiac arrest (OHCA). We investigated whether the serum potassium level on hospital arrival had prognostic indications for patients with OHCA. METHODS This prospective, multicenter observational study conducted in Osaka, Japan (CRITICAL study) enrolled consecutive patients with OHCA transported to 14 participating institutions from 2012 to 2016. We included adult patients aged ⩾18 years with OHCA of cardiac origin who achieved return of spontaneous circulation and whose serum potassium level on hospital arrival was available. Based on the serum potassium level, patients were divided into four quartiles: Q1 (K ⩽3.8 mEq/L), Q2 (3.8< K⩽4.5 mEq/L), Q3 (4.5< K⩽5.6 mEq/L) and Q4 (K >5.6 mEq/L). The primary outcome was one-month survival with favorable neurological outcome, defined as cerebral performance category scale 1 or 2. RESULTS A total of 9822 patients were registered, and 1516 of these were eligible for analyses. The highest proportion of favorable neurological outcome was 44.8% (189/422) in Q1 group, followed by 30.3% (103/340), 11.7% (44/375) and 4.5% (17/379) in the Q2, Q3 and Q4 groups, respectively (p<0.001). In the multivariable analysis, the proportion of favorable neurological outcome decreased as the serum potassium level increased (p<0.001). CONCLUSIONS High serum potassium level was significantly and dose-dependently associated with poor neurological outcome. Serum potassium on hospital arrival would be one of the effective prognostic indications for OHCA achieving return of spontaneous circulation.
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Doing 'business as usual' comes with a cost: evaluating energy cost of maintaining plant intracellular K+ homeostasis under saline conditions.
Rubio, F, Nieves-Cordones, M, Horie, T, Shabala, S
The New phytologist. 2020;(3):1097-1104
Abstract
Salinization of agricultural lands is a major threat to agriculture. Many different factors affect and determine plant salt tolerance. Nonetheless, there is a consensus on the relevance of maintaining an optimal cytosolic potassium : sodium ion (K+ : Na+ ) ratio for salinity tolerance in plants. This ratio depends on the operation of plasma membrane and tonoplast transporters. In the present review we focus on some aspects related to the energetic cost of maintaining that K+ : Na+ ratio. One of the factors that affect the cost of the first step of K+ acquisition - root K+ uptake through High Affinity K+ transporter and Arabidopsis K+ transport system 1 transport systems - is the value of the plasma membrane potential of root cells, a parameter that may differ amongst plant species. In addition to its role in nutrition, cytosolic K+ also is important for signalling, and K+ efflux through gated outward-rectifying K+ and nonselective cation channels can be regarded as a switch to redirect energy towards defence reactions. In maintaining cytosolic K+ , the great buffer capacity of the vacuole should be considered. The possible role of high-affinity K+ transporters (HKT)2s in mediating K+ uptake under saline conditions and the importance of cycling of K+ throughout the plant also are discussed.
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Urinary Albumin, Sodium, and Potassium and Cardiovascular Outcomes in the UK Biobank: Observational and Mendelian Randomization Analyses.
Zanetti, D, Bergman, H, Burgess, S, Assimes, TL, Bhalla, V, Ingelsson, E
Hypertension (Dallas, Tex. : 1979). 2020;(3):714-722
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Abstract
Urinary biomarkers are associated with cardiovascular disease, but the nature of these associations is not well understood. We performed multivariable-adjusted regression models to assess associations of random spot measurements of the urine sodium-potassium ratio (UNa/UK) and urine albumin adjusted for creatinine with cardiovascular risk factors, cardiovascular disease, and type 2 diabetes mellitus (T2D) in 478 311 participants of the UK Biobank. Further, we assessed the causal relationships of these kidney biomarkers, used as proxies for kidney function, with cardiovascular outcomes using the 2-sample Mendelian randomization approach. In observational analyses, UNa/UK showed significant inverse associations with atrial fibrillation, coronary artery disease, ischemic stroke, lipid-lowering medication, and T2D. In contrast, urine albumin adjusted for creatinine showed significant positive associations with atrial fibrillation, coronary artery disease, heart failure, hemorrhagic stroke, lipid-lowering medication, and T2D. We found a positive association between UNa/UK and albumin with blood pressure (BP), as well as with adiposity-related measures. After correcting for potential horizontal pleiotropy, we found evidence of causal associations of UNa/UK and albumin with BP (β systolic BP ≥2.63; β diastolic BP ≥0.85 SD increase in BP per SD change in UNa/UK and urine albumin adjusted for creatinine; P≤0.04), and of albumin with T2D (odds ratio=1.33 per SD change in albumin, P=0.02). Our comprehensive study of urinary biomarkers performed using state-of-the-art analyses of causality mirror and extend findings from randomized interventional trials which have established UNa/UK as a risk factor for hypertension. In addition, we detect a causal feedback loop between albumin and hypertension, and our finding of a bidirectional causal association between albumin and T2D reflects the well-known nephropathy in T2D.
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Assessment of a downsized potassium adsorption filter designed to transfuse neonates.
Ogasawara, K, Ohto, H, Takano, N, Nollet, KE, Go, H, Sato, M, Momoi, N, Hosoya, M
Transfusion. 2020;(11):2494-2499
Abstract
BACKGROUND During storage, the potassium level of red blood cell (RBC) components increases, especially after irradiation. Neonates are prone to hyperkalemia, for example, non-oliguric hyperkalemia, so using potassium adsorption filters during transfusion may be helpful. To overcome dilution of RBC components caused by saline priming of existing potassium adsorption filters, a downsized potassium adsorption filter for neonates (PAF-n, Kawasumi Laboratories Inc., Tokyo, Japan) was developed. STUDY DESIGN AND METHODS To assess the performance of PAF-n, its adsorption efficiency and RBC recovery rate were evaluated by testing pre-filtration and serial post-filtration (0-30 mL, 30-60 mL, 60-90 mL, and 90-120 mL) samples from 8 RBC components. RESULTS The average potassium adsorption rate of the PAF-n was 90.5% ± 0.78%, and never less than 89.0% in any of 8 RBC components. RBC recovery rates were 99.3% ± 1.12%. CONCLUSION The PAF-n showed an effective potassium ability with negligible RBC dilution.
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Effect of Steamed Potato Bread Intake on Glucose, Lipids, and Urinary Na+ and K+: A Randomized Controlled Trial with Adolescents.
Xu, H, Guo, Y, Lu, S, Ma, Y, Wang, X, Zhao, L, Sun, J
International journal of environmental research and public health. 2020;(6)
Abstract
Although potatoes are highly nutritious, many epidemiological studies have connected their consumption with abnormal lipids, diabetes, and hypertension. Steamed potato bread has recently become one of China's staple foods. A randomized controlled trial was designed to evaluate the effect of steamed potato bread consumption on Chinese adolescents. Four classes from a high school were randomly selected and assigned to the intervention group (two classes) or control group (two classes). The steamed wheat bread (100% raw wheat flour) and potato bread (raw wheat flour to cooked potato flour ratio of 3:7) were provided to the control group and intervention group as staple food once a school day for 8 weeks, respectively. Compared with the control group, the intervention group had significant net changes in systolic blood pressure (4.6 mmHg, p = 0.010), insulin (-4.35 mIU/L, p < 0.001), total cholesterol (-0.13 mmol/L, p = 0.032), and high-density lipoproteins cholesterol (-0.07 mmol/L, p = 0.010). The urinary level of Na+/K+ did not differ between the groups. In conclusion, the intake of steamed potato bread for 8 weeks resulted in positive effects on the total cholesterol and insulin profiles but a negative effect on the systolic blood pressure and high-density lipoproteins cholesterol of adolescents.
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Potassium infusion increases the likelihood of conversion of recent-onset atrial fibrillation-A single-blinded, randomized clinical trial.
Tazmini, K, Fraz, MSA, Nymo, SH, Stokke, MK, Louch, WE, Øie, E
American heart journal. 2020;:114-124
Abstract
BACKGROUND The optimal antiarrhythmic management of recent-onset atrial fibrillation (ROAF) or atrial flutter is controversial and there is a considerable variability in clinical treatment strategies. It is not known if potassium infusion has the potential to convert ROAF or atrial flutter to sinus rhythm (SR). Therefore, we aimed to investigate if patients with ROAF or atrial flutter and plasma-potassium levels ≤4.0 mmol/L have increased probability to convert to SR if the plasma-potassium level is increased towards the upper reference range (4.1-5.0 mmol/L). METHODS In a placebo-controlled, single-blinded trial, patients with ROAF or atrial flutter and plasma-potassium ≤4.0 mmol/L presenting between April 2013 and November 2017 were randomized to receive potassium chloride (KCl) infusion (n = 60) or placebo (n = 53). Patients in the KCl group received infusions at one of three different rates: 9.4 mmol/h (n = 11), 12 mmol/h (n = 19), or 15 mmol/h (n = 30). RESULTS There was no statistical difference in the number of conversions to SR between the KCl group and placebo [logrank test, P = .29; hazard ratio (HR) 1.20 (CI 0.72-1.98)]. However, KCl-infused patients who achieved an above-median hourly increase in plasma-potassium (>0.047 mmol/h) exhibited a significantly higher conversion rate compared with placebo [logrank P = .002; HR 2.40 (CI 1.36-4.21)] and KCl patients with below-median change in plasma-potassium [logrank P < .001; HR 4.41 (CI 2.07-9.40)]. Due to pain at the infusion site, the infusion was prematurely terminated in 10 patients (17%). CONCLUSIONS Although increasing plasma-potassium levels did not significantly augment conversion of ROAF or atrial flutter to SR in patients with potassium levels in the lower-normal range, our results indicate that this treatment may be effective when a rapid increase in potassium concentration is tolerated and achieved.