Hyperkalemia: pathophysiology, risk factors and consequences

Paper-Based Optode Devices (PODs) for Selective Quantification of Potassium in Biological Fluids

This paper describes the design, fabrication, and feasibility of paper-based optode devices (PODs) for sensing potassium selectively in biological fluids. PODs operate in exhaustive mode and integrate with a handheld, smartphone-connected optical reader. This integrated measuring system provides significant advantages over traditional optode membranes and other paper-based designs, by obtaining a linear optical response to potassium concentration via a simple, stackable design and by harnessing a smartphone to provide an easy-to-use interface, thus enabling remote monitoring of diseases.

Hyperkalemia excursions are associated with an increased risk of mortality and hospitalizations in hemodialysis patients

BACKGROUND

Hyperkalemia is common among hemodialysis (HD) patients and has been associated with adverse clinical outcomes. Previous studies considered a single serum potassium (K) measurement or time-averaged values, but serum K excursions out of the target range may be more reflective of true hyperkalemia events. We assessed whether hyperkalemia excursions lead to an elevated risk of adverse clinical outcomes.

METHODS

Using data from 21 countries in Phases 4-6 (2009-18) of the Dialysis Outcomes and Practice Patterns Study (DOPPS), we investigated the associations between peak serum K level, measured monthly predialysis, over a 4-month period ('peak K') and clinical outcomes over the subsequent 4 months using Cox regression, adjusted for potential confounders.

RESULTS

The analysis included 62 070 patients contributing a median of 3 (interquartile range 2-6) 4-month periods. The prevalence of hyperkalemia based on peak K was 58% for >5.0, 30% for >5.5 and 12% for >6.0 mEq/L. The all-cause mortality hazard ratio for peak K (reference ≤5.0 mEq/L) was 1.15 [95% confidence interval (CI) 1.09, 1.21] for 5.1-5.5 mEq/L, 1.19 (1.12, 1.26) for 5.6-6.0 mEq/L and 1.33 (1.23, 1.43) for >6.0 mEq/L. Results were qualitatively consistent when analyzing hospitalizations and a cardiovascular composite outcome.

CONCLUSIONS

Among HD patients, we identified a lower K threshold (peak K 5.1-5.5 mEq/L) than previously reported for increased risk of hospitalization and mortality, with the implication that a greater proportion (>50%) of the HD population may be at risk. A reassessment of hyperkalemia severity ranges is needed, as well as an exploration of new strategies for effective management of chronic hyperkalemia.

Association Between Long-Term Use of Non-steroidal Anti-inflammatory Drugs and Hyperkalemia in Diabetic Patients

Introduction

The association between continuous use of nonsteroidal anti-inflammatory drugs (NSAIDs) and hyperkalemia is not consistent in the literature and creates grounds for further large-scale trials, particularly in patients with a chronic disease that affects renal function, such as diabetes mellitus (DM). In this study, we will compare mean serum potassium level and the prevalence of hyperkalemia in diabetic and non-diabetic patients based on their use of NSAIDs.

Methods

This case-control study was conducted in the internal medicine unit of a tertiary care hospital from May 2019 to December 2020. After taking informed consent, 700 patients with a confirmed diagnosis of type 2 DM, of either gender, were enrolled in the study via consecutive convenient non-probability technique. Another set of 700 participants from the public were enrolled as the reference or control group. Continuous NSAID use was defined as NSAID used for a minimum of 20 days in the last 30 days. Blood was drawn via phlebotomy and sent to the laboratory to test for potassium level.

Results

Serum potassium level was significantly higher in diabetic patients with continuous NSAID use compared to the diabetic patients without continuous use (4.8 ± 0.8 mmol/L vs. 4.5 ± 0.7 mmol/L; p-value: 0.0001). Additionally, serum potassium level was significantly higher in non-diabetic patients with continuous NSAID use compared to non-diabetic patients without continuous use (4.3 ± 0.7 mmol/L vs. 3.9 ± 0.5 mmol/L; p-value: 0.0001) 

Conclusion

In this study, the patients with continuous use of NSAIDs had higher levels of serum potassium level compared to patients without continuous use of NSAIDs. This difference was even higher in diabetic patients.

High Prevalence of Multimorbidity and Polypharmacy in Elderly Patients With Chronic Pain Receiving Home Care are Associated With Multiple Medication-Related Problems

Aim: To measure the extent of polypharmacy, multimorbidity and potential medication-related problems in elderly patients with chronic pain receiving home care. Methods: Data of 355 patients aged ≥65 years affected by chronic pain in home care who were enrolled in the ACHE study in Berlin, Germany, were analyzed. History of chronic diseases, diagnoses, medications including self-medication were collected for all patients. Multimorbidity was defined as the presence of ≥2 chronic conditions and levels were classified by the Charlson-Comorbidity-Index. Polypharmacy was defined as the concomitant intake of ≥5 medications. Potentially clinically relevant drug interactions were identified and evaluated; underuse of potentially useful medications as well as overprescription were also assessed. Results: More than half of the patients (55.4%) had moderate to severe comorbidity levels. The median number of prescribed drugs was 9 (range 0-25) and polypharmacy was detected in 89.5% of the patients. Almost half of them (49.3%) were affected by excessive polypharmacy (≥10 prescribed drugs). Polypharmacy and excessive polypharmacy occurred at all levels of comorbidity. We detected 184 potentially relevant drug interactions in 120/353 (34.0%) patients and rated 57 (31.0%) of them as severe. Underprescription of oral anticoagulants was detected in 32.3% of patients with atrial fibrillation whereas potential overprescription of loop diuretics was observed in 15.5% of patients. Conclusion: Multimorbidity and polypharmacy are highly prevalent in elderly outpatients with chronic pain receiving home care. Medication-related problems that could impair safety of drug treatment in this population are resulting from potentially relevant drug interactions, overprescribing as well as underuse.

The pharmacotherapeutic management of hyperkalemia in patients with cardiovascular disease

Introduction: Patients with cardiovascular diseases (CVD) are at increased risk of hyperkalemia, particularly when treated with renin-angiotensin-aldosterone inhibitors (RAASIs). Because the occurrence or fear of hyperkalemia, RAASIs are frequently down-titrated or discontinued in patients with CVD, with consequent worse outcomes than patients who remain on maximum doses.Areas covered: This article reviews potassium homeostasis, epidemiology, risk factors, and outcomes of hyperkalemia, and efficacy and safety of the drugs used for acute and chronic treatment of hyperkalemia. A literature search was carried out using the PubMed and guidelines for the management of hyperkalemia.Expert opinion: The emergency treatment of hyperkalemia is not supported by high-quality evidence and clinical trials did not report drug effects on clinical outcomes. Two potassium binders, patiromer and sodium zirconium cyclosilicate, represent a new approach in the treatment of chronic hyperkalemia as they may allow the titration and maintenance of guidelines-recommended doses of RAASIs in patients with CVD who otherwise would not tolerate them due to the risk of hyperkalemia.Further studies are needed to evaluate the safety and efficacy of drug therapy and support the development of guidelines for acute and chronic hyperkalemia.

Deletion of renal Nedd4-2 abolishes the effect of high sodium intake (HS) on Kir4.1, ENaC, and NCC and causes hypokalemia during high HS

Neural precursor cell expressed developmentally downregulated protein 4-2 (Nedd4-2) regulates the expression of Kir4.1, thiazide-sensitive NaCl cotransporter (NCC), and epithelial Na⁺ channel (ENaC) in the aldosterone-sensitive distal nephron (ASDN), and Nedd4-2 deletion causes salt-sensitive hypertension. We now examined whether Nedd4-2 deletion compromises the effect of high-salt (HS) diet on Kir4.1, NCC, ENaC, and renal K⁺ excretion. Immunoblot analysis showed that HS diet decreased the expression of Kir4.1, Ca²⁺-activated large-conductance K⁺ channel subunit-α (BKα), ENaCβ, ENaCγ, total NCC, and phospho-NCC (at Thr⁵³) in floxed neural precursor cell expressed developmentally downregulated gene 4-like (Nedd4l^fl/fl) mice, whereas these effects were absent in kidney-specific Nedd4-2 knockout (Ks-Nedd4-2 KO) mice. Renal clearance experiments also demonstrated that Nedd4-2 deletion abolished the inhibitory effect of HS diet on hydrochlorothiazide-induced natriuresis. Patch-clamp experiments showed that neither HS diet nor low-salt diet had an effect on Kir4.1/Kir5.1 currents of the distal convoluted tubule in Nedd4-2-deficient mice, whereas we confirmed that HS diet inhibited and low-salt diet increased Kir4.1/Kir5.1 activity in Nedd4l^flox/flox mice. Nedd4-2 deletion increased ENaC currents in the ASDN, and this increase was more robust in the cortical collecting duct than in the distal convoluted tubule. Also, HS-induced inhibition of ENaC currents in the ASDN was absent in Nedd4-2-deficient mice. Renal clearance experiments showed that HS intake for 2 wk increased the basal level of renal K⁺ excretion and caused hypokalemia in Ks-Nedd4-2-KO mice but not in Nedd4l^flox/flox mice. In contrast, plasma Na⁺ concentrations were similar in Nedd4l^flox/flox and Ks-Nedd4-2 KO mice on HS diet. We conclude that Nedd4-2 plays an important role in mediating the inhibitory effect of HS diet on Kir4.1, ENaC, and NCC and is essential for maintaining normal renal K⁺ excretion and plasma K⁺ ranges during long-term HS diet.NEW & NOTEWORTHY The present study suggests that Nedd4-2 is involved in mediating the inhibitory effect of high salt (HS) diet on Kir4.1/kir5.1 in the distal convoluted tubule, NaCl cotransporter function, and epithelial Na⁺ channel activity and that Nedd4-2 plays an essential role in maintaining K⁺ homeostasis in response to a long-term HS diet. This suggests the possibility that HS intake could lead to hypokalemia in subjects lacking proper Nedd4-2 E3 ubiquitin ligase activity in aldosterone-sensitive distal nephron.

Incidence of hyperkalemia during hypertonic saline test for the diagnosis of diabetes insipidus

OBJECTIVE

Hyperkalemia has been reported upon different hypertonic saline infusion protocols. Since hypertonic saline test has recently been validated for the differential diagnosis of diabetes insipidus (DI), we aimed to investigate the course of plasma potassium during the test.

DESIGN

We analyzed data of 90 healthy volunteers and 141 patients with polyuria-polydipsia syndrome (PPS) from two prospective studies evaluating the hypertonic saline test. Our primary outcome was the incidence rate of hypertonic saline-induced hyperkalemia > 5 mmol/L.

METHODS

Participants received a 250 mL bolus of 3% NaCl solution, followed by 0.15 mL/min/kg body weight continuously infused targeting a plasma sodium level of 150 mmol/L. Blood samples and clinical data were collected every 30 min.

RESULTS

Of the 231 participants, 16% (n = 37/231) developed hyperkalemia. The incidence of hyperkalemia was higher in healthy volunteers and in patients with primary polydipsia (25.6% (n = 23/90) and 9.9% (n = 14/141), respectively), and only occurred in 3.4% (n = 2/59) of patients with diabetes insipidus. Hyperkalemia developed mostly at or after 90-min test duration (81.1%, n => 30/37). Predictors of hyperkalemia (OR (95% CI)) were male sex (2.9 (1.2-7.4), P => 0.02), a plasma potassium at baseline > 3.9 mmol/L (5.2 (1.8-17.3), P => 0.004), normonatremia at 30-min test duration (3.2 (1.2-9.5), P => 0.03), and an increase in potassium levels already at 30-min test duration as compared to baseline (4.5 (1.7-12.3), P => 0.003). Hyperkalemia was transient and resolved spontaneously in all cases.

CONCLUSION

The hypertonic saline test can lead to hyperkalemia, especially in patients with primary polydipsia who experience a longer test duration. Monitoring potassium levels in these patients is recommended.

Risk factors associated with the incidence and recurrence of hyperkalaemia in patients with cardiorenal conditions

INTRODUCTION

Hyperkalaemia (HK) is associated with increased mortality risk. Prior studies suggest that the causes of HK are multifactorial. This study aimed to examine risk factors for incident and recurrent HK in six large real-world cohorts of UK patients that could be considered at elevated HK risk because of underlying disease pathology and/or medication use.

METHODS

This retrospective, observational cohort study utilised UK primary and secondary care data from Clinical Practice Research Datalink (CPRD) and linked Hospital Episode Statistics (HES), respectively. Patients were included if they were aged ≥18 years and had a record of ≥1 condition of interest (chronic kidney disease [CKD] stage 3+, heart failure, resistant hypertension [RHTN], dialysis, diabetes) and/or renin-angiotensin-aldosterone system inhibitors (RAASi) use between 01 January 2003 and 30 June 2018. Based on their diagnosis/ RAASi prescription record, patients were assigned to overlapping cohorts. The outcomes assessed were HK and recurrent HK, the latter defined as second or subsequent HK episode during follow-up. HK was defined as a serum K⁺ measurement ≥5.0 mmol/L; thresholds of ≥5.5 and ≥ 6.0 mmol/L were also explored.

RESULTS

Of 931 460 meeting the eligibility criteria, 310 535 (33.3%) patients experienced ≥1 HK event and 187 719 (20.2%) experienced HK recurrence. The probability of subsequent HK events increased with event number from 60.5% for the second event to 76.5% for the sixth and the corresponding time to the next HK event decreased from 15.8 months to 6.1 months. Amongst the key risk factors, serum creatinine, serum phosphorus, systolic blood pressure, and white cell count demonstrated direct relationships with incidence and recurrence of HK, while inverse relationships were observed for estimated glomerular filtration rate (eGFR), haemoglobin and diastolic blood pressure. The relationship for Charlson's Comorbidity Index was mixed. The use of RAASi and anti-hyperglycaemic agents was associated with an increased risk of HK, while the use of diuretics (non-K⁺ -sparing) was protective against HK.

CONCLUSION

Several risk factors for HK that are easily measured in routine clinical practice were identified, facilitating the identification of patients who are at the highest risk of experiencing HK, including recurrent HK.

The safety and efficacy of low-dose mineralocorticoid receptor antagonists in dialysis patients: A meta-analysis

INTRODUCTION

Our aim was to evaluate the safety and efficacy of low-dose mineralocorticoid receptor antagonists (MRAs) in dialysis patients.

METHODS

We systematically searched PubMed, EMBASE, and Cochrane libraries for clinical trials on the use of MRAs in dialysis patients. Review Manager 5.3 software was used to analyze relevant data and evaluate the quality of evidence.

RESULTS

We identified nine randomized controlled trials including 1128 chronic dialysis patients. In terms of safety, when hyperkalemia was defined as serum potassium level ≥5.5 mmol/L, low-dose MRAs were significantly associated with hyperkalemia (relative risk [RR] 1.76, 95% confidence intervals [CI] 1.07-2.89, P = .02); however, when hyperkalemia was defined as serum potassium level ≥6.0 mmol/L or serum potassium level ≥6.5 mmol/L, no significant association was observed between low-dose MRAs and hyperkalemia (RR 1.40, 95% CI 0.83-2.37, P = .20; RR 1.98, 95% CI 0.91-4.30, P = .09, respectively). Use of low-dose MRAs can reduce cardiovascular mortality by 54% compared with the control group (0.46, 95% CI 0.28-0.76, P = .003). Similarly, the RR of all-cause mortality for the low-dose MRAs group was 0.48 (95% CI 0.33-0.72, P = .0003).

CONCLUSION

Low-dose MRAs may benefit dialysis patients without significantly increasing moderate to severe hyperkalemia.

Increased colonic K+ excretion through inhibition of the H,K-ATPase type 2 helps reduce plasma K+ level in a murine model of nephronic reduction

Hyperkalemia is frequently observed in patients at the end-stage of chronic kidney disease (CKD), and has possible harmful consequences on cardiac function. Many strategies are currently used to manage hyperkalemia, one consisting of increasing fecal K⁺ excretion through the administration of cation-exchange resins. In this study, we explored another more specific method of increasing intestinal K⁺ secretion by inhibiting the H,K-ATPase type 2 (HKA2), which is the main colonic K⁺ reabsorptive pathway. We hypothetised that the absence of this pump could impede the increase of plasma K⁺ levels following nephronic reduction (N5/6) by favoring fecal K⁺ secretion. In N5/6 WT and HKA2KO mice under normal K⁺ intake, the plasma K⁺ level remained within the normal range, however, a load of K⁺ induced strong hyperkalemia in N5/6 WT mice (9.1 ± 0.5 mM), which was significantly less pronounced in N5/6 HKA2KO mice (7.9 ± 0.4 mM, p < 0.01). This was correlated to a higher capacity of HKA2KO mice to excrete K⁺ in their feces. The absence of HKA2 also increased fecal Na⁺ excretion by inhibiting its colonic ENaC-dependent absorption. We also showed that angiotensin-converting-enzyme inhibitor like enalapril, used to treat hypertension during CKD, induced a less severe hyperkalemia in N5/6 HKA2KO than in N5/6 WT mice. This study therefore provides the proof of concept that the targeted inhibition of HKA2 could be a specific therapeutic maneuver to reduce plasma K⁺ levels in CKD patients.

Impact of a pharmacist-based multidimensional intervention aimed at decreasing the risk of hyperkalemia in heart failure patients: A Latin-American experience

AIMS

Hyperkalemia is a potentially life-threatening condition associated with the use of heart failure (HF) medications, which can lead to increased morbidity and mortality. Novel approaches for hyperkalemia prevention are needed, especially in limited-resource settings. Despite multiple studies showing the beneficial impact of pharmaceutical-counseling in several outcomes, there is a knowledge-gap regarding its impact on hyperkalemia prevention.

METHODS

A case-control study was performed in patients from the Adult Heart Failure Clinic Registry in our institution. Cases were selected using a definition of serum potassium K+ ≥5.5 mmol/L. To study the association between hyperkalemia and relevant risk factors, we performed a multivariate logistic regression analysis using the Least Absolute Shrinkage and Selection Operator (LASSO) method for variable selection. We also fitted a Classification and Regression Tree (CART) to establish complex interactions and effect modifiers between the selected variables.

RESULTS

We matched 483 controls (eligible HF patients without hyperkalemia) to 132 cases (eligible HF patients with hyperkalemia based on age and calendar, yielding a total sample size of 615 patients (270 females) for this study. Cases had statistically significant lower odds of receiving a pharmacist-based multidimensional intervention (PBMI) (OR 0.57; 95% CI, 0.43-0.80) or having HF with reduced ejection fraction (OR 0.56; 95% CI, 0.18-0.72). On the other hand, patients who presented hyperkalemia had statistically significant higher odds of having a history of chronic kidney disease stage 4 (OR 4.97; 95% CI, 2.24-11.01) or 5 (OR 6.73; 95% CI, 1.69-26.84) and being on enalapril at doses =40 mg/day (OR, 9.90; 95% CI 5.81-16.87).

CONCLUSIONS

PBMI is a practical approach to prevent hyperkalemia in HF patients in a limited-resource setting. However, clinical trials are needed to assess its effectiveness.

New Treatment Options for Hyperkalemia in Patients with Chronic Kidney Disease

Hyperkalemia may cause life-threatening cardiac and neuromuscular alterations, and it is associated with high mortality rates. Its treatment includes a multifaceted approach, guided by potassium levels and clinical presentation. In general, treatment of hyperkalemia may be directed towards stabilizing cell membrane potential, promoting transcellular potassium shift and lowering total K+ body content. The latter can be obtained by dialysis, or by increasing potassium elimination by urine or the gastrointestinal tract. Until recently, the only therapeutic option for increasing fecal K+ excretion was represented by the cation-exchanging resin sodium polystyrene sulfonate. However, despite its common use, the efficacy of this drug has been poorly studied in controlled studies, and concerns about its safety have been reported. Interestingly, new drugs, namely patiromer and sodium zirconium cyclosilicate, have been developed to treat hyperkalemia by increasing gastrointestinal potassium elimination. These medications have proved their efficacy and safety in large clinical trials, involving subjects at high risk of hyperkalemia, such as patients with heart failure and chronic kidney disease. In this review, we discuss the mechanisms of action and the updated data of patiromer and sodium zirconium cyclosilicate, considering that the availability of these new treatment options offers the possibility of improving the management of both acute and chronic hyperkalemia.