Dietary potassium intake, kidney function, and survival in a nationally representative cohort

BACKGROUND

In healthy adults, higher dietary potassium intake is recommended given that potassium-rich foods are major sources of micronutrients, antioxidants, and fiber. Yet among patients with advanced kidney dysfunction, guidelines recommend dietary potassium restriction given concerns about hyperkalemia leading to malignant arrhythmias and mortality.

OBJECTIVES

Given sparse data informing these recommendations, we examined associations of dietary potassium intake with mortality in a nationally representative cohort of adults from the NHANES.

METHODS

We examined associations between daily dietary potassium intake scaled to energy intake (mg/1000 kcal), ascertained by 24-h dietary recall, and all-cause mortality among 37,893 continuous NHANES (1999-2014) participants stratified according to impaired and normal kidney function (estimated glomerular filtration rates <60 and ≥60 mL · min-1 · 1.73 m-2, respectively) using multivariable Cox models. We also examined the impact of the interplay between dietary potassium, source of potassium intake (animal- compared with plant-based sources), and coexisting macronutrient and mineral consumption upon mortality.

RESULTS

Among participants with impaired and normal kidney function, the lowest tertile of dietary potassium scaled to energy intake was associated with higher mortality (ref: highest tertile) [adjusted HR (aHR): 1.18; 95% CI: 1.02, 1.38 and aHR: 1.17; 95% CI: 1.06, 1.28, respectively]. Compared with high potassium intake from plant-dominant sources, participants with low potassium intake from animal-dominant sources had higher mortality irrespective of kidney function. Among participants with impaired kidney function, pairings of low potassium intake with high protein, low fiber, or high phosphorus consumption were each associated with higher death risk.

CONCLUSIONS

Lower dietary potassium scaled to energy intake was associated with higher mortality, irrespective of kidney function. There was also a synergistic relation of higher potassium intake, plant-based sources, and macronutrient/mineral consumption with survival. Further studies are needed to elucidate pathways linking potassium intake and coexisting dietary factors with survival in populations with and without chronic kidney disease.

Consensus-Based Recommendations for the Management of Hyperkalemia in the Hemodialysis Setting

Hyperkalemia (serum K⁺ >5.0 mmol/L) is commonly observed among patients receiving maintenance hemodialysis and associated with increased risk of cardiac arrhythmias. Current international guidelines may not reflect the latest evidence on managing hyperkalemia in patients undergoing hemodialysis, and there is a lack of high-quality published studies in this area. This consensus guideline aims to provide recommendations in relation to clinical practice. Available published evidence was evaluated through a systematic literature review, and the nominal group technique was used to develop consensus recommendations from a panel of experienced nephrologists, covering monitoring, dietary restrictions, prescription of K⁺ binders, and concomitant prescription of renin-angiotensin-aldosterone system inhibitors. Recent studies have shown that K⁺ binders reduce the incidence of hyperkalemia, but further evidence is needed in areas including whether reduced-K⁺ diets or treatment with K⁺ binders improve patient-centered outcomes. Treatment of hyperkalemia in the hemodialysis setting is complex, and decisions need to be tailored for individual patients.

Update on management of hypokalemia and goals for the lower potassium level in patients with cardiovascular disease: A review in collaboration with the European Society of Cardiology Working Group on Cardiovascular Pharmacotherapy

Hypokalaemia is common in patients with cardiovascular disease. In this review, we emphasize the importance of tight potassium regulation in patients with cardiovascular disease based on findings from observational studies. To enhance the understanding, we also describe the mechanisms of potassium homeostasis maintenance, the most common causes of hypokalaemia and present strategies for monitoring and management of low potassium levels. We propose elevation of potassium in asymptomatic patients with lower normal concentrations and concurrent cardiovascular disease. These proposals are intended to assist clinicians until more evidence is available.

Potassium Trajectories prior to Dialysis and Mortality following Dialysis Initiation in Patients with Advanced CKD

INTRODUCTION

Patients with advanced non-dialysis-dependent CKD (NDD-CKD) have a reduced ability for maintaining plasma potassium (K) in normal range. Deviation from normal plasma K ranges is associated with increased mortality; however, the average trajectory of plasma K over time in patients with advanced NDD-CKD and the outcomes associated with plasma K trajectory are unknown.

METHODS

We identified 34,167 US veterans with advanced NDD-CKD transitioning to dialysis between October 2007 and March 2015 with at least 1 K measurement each year over a 3-year period prior to dialysis transition (3-year prelude). The K trajectory defined as the change in K (slope) per year over the entire 3-year prelude was estimated using linear mixed-effects models. The association between unadjusted (crude) K slope (categorized as stable [-0.09 to 0.09 mEq/L/year], decreasing [≤-0.10 mEq/L/year], and increasing [≥0.10 mEq/L/year]) and time to all-cause and cardiovascular mortality during the 6 months following dialysis initiation was assessed using multivariable-adjusted survival models.

RESULTS

The crude and multivariable-adjusted K slopes (mean, 95% CI) over the 3-year prelude were 0.008 (0.0059, 0.0110) and -0.15 mEq/L/year (-0.19, -0.11), respectively. Decreasing K slope was associated with higher multivariable-adjusted risk of all-cause mortality (adjusted hazard ratio [95% CI] vs. stable K slope: 1.08 [1.00-1.17]). No association was observed between K slope and cardiovascular mortality.

DISCUSSION/CONCLUSION

The average intraindividual plasma K trajectory is remarkably stable in patients with advanced NDD-CKD. A decreasing K slope is associated with higher all-cause mortality risk.