Myelotoxicity and kidney dysfunction related to the use of trimethoprim-sulfamethoxazole for the treatment of Pneumocystis jirovecii pneumonia: a case report of severe adverse events with a common drug.

Trimethoprim-sulfamethoxazole (TMP-SMX) is the primary therapeutic option for Pneumocystis jirovecii pneumonia (PCP). Gastrointestinal symptoms and cutaneous rash are common side effects, with hyperkalemia being uncommon in patients without kidney dysfunction, and myelotoxicity being even rarer. We present the case of a male patient with hypertension and a recent diagnosis of non-Hodgkin lymphoma, undergoing rituximab treatment for two months. He was admitted to the intensive care unit due to dyspnea, tachypnea, and pleuritic pain, requiring mechanical ventilation. Chest computed tomography showed bilateral and multilobed ground-glass opacities, compromising more than 80% of the lung parenchyma. Pulmonary tuberculosis and COVID-19 were ruled out. An angiotomography and Doppler ultrasound revealed an extensive pulmonary thrombus and deep venous thrombosis. Empiric treatment with TMP-SMX for PCP was initiated, but within four days, the patient experienced metabolic acidosis and severe hyperkalemia, necessitating hemodialysis. He also presented with progressive pancytopenia and critical levels of leukopenia and thrombocytopenia. The hypothesis of TMP-SMX-induced myelotoxicity was suspected. Considering the unavailability of an alternative treatment, it was opted to continue TMP-SMX and initiate a granulocyte-colony-stimulating factor. However, the patient maintained medullary deterioration, becoming refractory to the transfusion of blood derivates. On the 17th day of treatment, a clinical decision was made to suspend TMP-SMX, leading to improvements within 48 hours in marrow and kidney functions, metabolic acidosis, and hyperkalemia. Despite all efforts, the patient died after 35 days of hospitalization due to hospital-acquired infections. This case highlights the importance of clinicians recognizing potential myelotoxicity with TMP-SMX and promptly discontinuing the drug if necessary.

Comparison of chronic kidney disease progression and associated complications between geriatric and non-geriatric groups.

There is no consensus on the physiologic decline in estimated glomerular filtration rate (GFR) due to geriatric conditions related with the aging or chronic kidney disease (CKD) itself. In this study, we aimed to compare the CKD progression and associated complications in a large sample of geriatric and non-geriatric patients. The data of in 506 patients at age between 30 to 90 years and diagnosed with CKD at stage 2 and above (15 mL/min/1.73 m2 ≤ eGFR < 90 mL/min/1.73 m2) were collected retrospectively and compared among geriatric (>65 years old) and non-geriatric individuals. The rate of hypertension was higher in geriatrics compared to non-geriatrics (96.6% vs 91.9%, P = .04). Among laboratory findings, only PTH level was significantly lower and HCO3 concentration was higher in geriatrics compared to non-geriatrics (P = .02, P < .001, respectively). There was no significant difference in last measured eGFR (P = .99) while that measured 4 years ago was lower in geriatrics compared to that of non-geriatrics (P < .001). eGFR change was smaller in geriatrics compared to non-geriatrics (P < .001), and rate of progressive renal disease among non-geriatric group (39%) was found to be significantly higher than in the geriatrics (17.2%) (P < .001). The prevalence of hyperkalemia was lower in geriatrics at stage 3a (P = .02); prevalence of hyperparathyroidism was lower in those at stage 3b (P = .02) and lastly the acidosis was observed significantly lower in geriatric patients at stage 3a, 3b, and 4 compared to the non-geriatrics at corresponding stages (P < .001, P = .03, and P = .04, respectively). The eGFR change was significantly smaller in geriatrics at stage 3b and 4 (P < .001 and P = .04, respectively) while the rate of progressed renal disease was lower in geriatrics at stage 3a and 3b (21.1% vs 9.9%, P = .03 and 41.2% vs 11.1%, P < .001, respectively). eGFR change in 4-year period and the rates of progressive renal disease are higher in the non-geriatrics and also the prevalence of secondary complications of CKD, such as hyperparathyroidism, acidosis, and hyperkalemia, are higher in non-geriatrics. This may reflect that decline of GFR in geriatric individuals is at least partially related to physiological aging rather than kidney disease. Therefore, devising age related CKD definitions might be appropriate.

A rare case of essential thrombocythemia with pseudo-hyperkalemia.

Essential thrombocythemia (ET) is a rare clonal stem cell disorder that affects the production of platelets in the bone marrow. This condition causes an overproduction of platelets, which can lead to blood clots and other complications. Potassium, on the other hand, is an essential mineral that plays a vital role in various bodily functions, including nerve impulses and muscle contractions. Here, in this case report, we investigated a case of pseudo-hyperkalemia caused by essential thrombocythemia in a 77-year-old woman with very high platelet counts. Moreover, this case report, which has no similar examples in the literature review, is important for clinicians.

Randomised, blinded, cross-over evaluation of the palatability of and preference for different potassium binders in participants with chronic hyperkalaemia in the USA, Canada and Europe: the APPETIZE study.

OBJECTIVES: Traditional potassium (K+) binders for treating hyperkalaemia are unpalatable and poorly tolerated. Newer K+ binders are reportedly better tolerated; however, no published data describe their palatability, a determinant of long-term adherence. This study evaluated the palatability of and preference for three K+ binders: sodium and calcium polystyrene sulfonate (S/CPS), sodium zirconium cyclosilicate (SZC) and calcium patiromer sorbitex (patiromer). DESIGN: Phase 4, randomised, participant-blinded, cross-over study. Participants were randomised to one of six taste sequences and, using a 'sip and spit' approach, tasted each K+ binder before completing a survey. SETTING: 17 centres across the USA, Canada and European Union. PARTICIPANTS: 144 participants with chronic kidney disease, hyperkalaemia and no recent use of K+ binders. MAIN OUTCOME MEASURES: For the primary (USA) and key secondary (Canada and European Union) endpoints, participants rated palatability attributes (taste, texture, smell and mouthfeel) and willingness to take each K+ binder on a scale of 0-10 (rational evaluation). Feelings about each attribute, and the idea of taking the product once daily, were evaluated using a non-verbal, visual measure of emotional response. Finally, participants ranked the K+ binders according to palatability. RESULTS: In each region, SZC and patiromer outperformed S/CPS on overall palatability (a composite of taste, texture, smell and mouthfeel), based on rational evaluation and emotional response. Taking the product once daily was more appealing for SZC and patiromer, creating greater receptivity than the idea of taking S/CPS. The emotional response to mouthfeel had the strongest influence on feelings about taking each product. In each region, a numerically greater proportion of participants ranked SZC as the most preferred K+ binder versus patiromer or S/CPS. CONCLUSIONS: Preference for more palatable K+ binders such as SZC and patiromer may provide an opportunity to improve adherence to long-term treatment of hyperkalaemia. TRIAL REGISTRATION NUMBER: NCT04566653.

Acute fatal ventricular arrhythmia induced by severe hyperkalemia in a toddler with decompensated methylmalonic acidemia.

BACKGROUND: Methylmalonic acidemia is a very rare genetic metabolic disease. Patients with isolated methylmalonic acidemia typically present with acute alterations of consciousness, failure to thrive, anorexia, vomiting, respiratory distress, and muscular hypotonia. Despite the evidence-based management, affected individuals experience significant morbidity and mortality. Hyperkalemia is one of the unusual complications of methylmalonic acidemia. CASE PRESENTATION: In this paper, we describe a 4-year-old Persian boy with methylmalonic acidemia who developed life-threatening arrhythmia following severe hyperkalemia and metabolic acidosis. Emergent management of the condition was successfully carried out, and the rhythm changed to normal sinus rhythm by effectively reducing the serum potassium level. We discuss the possible etiology of this lethal condition and describe its management on the basis of the available evidence. CONCLUSION: During metabolic decompensation in methylmalonic acidemia, frequent blood gas and electrolyte testing to prescribe and adjust therapy and annual echocardiogram and electrocardiogram screening are essential.

Combination Therapy Use and Associated Events in Clinical Practice Following Dissemination of Trial Findings: A De-Implementation Study Using Interrupted Time Series Analysis.

PURPOSE: It takes 17 years, on average, for trial results to be implemented into practice. Using data from the Department of Veterans Affairs (VA), this study assessed the potential impact on clinical practice of the dissemination of findings from a randomized, controlled trial reporting harm with the use of combination therapy. Communication between research and VA Pharmacy Benefits Management Services (PBM)  provided the impetus for communication from the PBM about the findings of the trial in accordance with policy. METHODS: In this de-implementation study, interrupted time series analysis was used for assessing prescribing patterns and adverse clinical events before and after the dissemination of the trial findings. The de-implementation strategy was multicomponent and multilevel. Strategies were aligned with categories outlined in the Expert Recommendations for Implementing Change: train and educate stakeholders, use evaluative and iterative strategies, develop stakeholder inter-relationships, change infrastructure, provide interactive assistance, and engage consumers. VA patients with type 2 diabetes mellitus, chronic kidney disease stages 1 to 3, and a moderate or severe albuminuria who received care between July 2008 and November 2017 were included. Patients were subgrouped according to treatment with an angiotensin-converting enzyme inhibitor + angiotensin receptor blocker. The primary end point was the prevalence of combination therapy use. Secondary end points were the incidences of acute kidney injury and hyperkalemia. FINDINGS: This study followed 712,245 patients, 9297 of whom used combination therapy. Data were available from 428,535 and 283,710 patients pre- and post-intervention, respectively; among these, 8324 and 973 patients used combination therapy, the median ages were 66 and 68 years, and 96.92% and 98.82% were men. One month following communication from the PBM, the reductions in combination therapy users, acute kidney injury events, and hyperkalemia were 331.94 (95% CI, 500.27-163.32), 36.58% (95% CI, 31.90%-41.95%), and 25.49% (95% CI, 14.17%-36.07%) per 100,000 patients per month, respectively (all, P < 0.001), whereas before the communication, these changes were +14.84 (95% CI, 10.27-19.42), -3.46% (95% CI, 3.18-3.74), and -3.27% (95% CI, 2.66%-3.87%) (all, P < 0.001). IMPLICATIONS: The apparent speed and impact of the implementation of changes resulting from the dissemination of trial findings into VA clinical practice are encouraging. The speed of implementation was much faster than average for health care providers in the United States. Established communications between research and clinical practice, as well as established policy and communications between PBM and clinical practice, may be a model for other health care organizations.

Association of Familial Hyperkalemia and Hypertension with Proximal Renal Tubular Acidosis and Epileptic Seizures.

INTRODUCTION: Familial hyperkalemic hypertension (FHHt) is an inherited disease characterized by hyperkalemia, hypertension, and hyperchloremic acidosis (HCA). The primary defect is a hyperactive sodium chloride co-transporter, expressed in the renal distal tubule. FHHt is caused by mutation in either WNK1, WNK4, KLHL3, or Cul3. The mechanism of HCA is not completely understood. METHODS: Clinical and genetic data were collected from the largest family with FHHt described in the literature. Urine ammonia was measured in 26 family members. Epilepsy was diagnosed clinically. RESULTS: Of the 85 family members, 44 are affected by the Q565E WNK4 mutation, and 28 are newly described. In genetically engineered mice, urinary ammonium was decreased. In our study, urine ammonium did not change. In 11 unaffected subjects, urine ammonia per creatinine was 8.013 ± 3.620 mm/mm, and in 15 subjects affected by FHHt, it was 8.990 ± 4.300 mm/mm (p = 0.546, not significant). Due to the large family size and prolonged follow-up, rare conditions can be identified. Indeed, two children have genetic generalized epilepsy and one child has migraine. The prevalence of epilepsy is 4.545% (2/44) much higher than in the general population (0.681%). This difference is statistically significant (χ2 with Yates correction = 5.127, p = 0.023). CONCLUSIONS: We provide further evidence that the origin of HCA in FHHt lies in the proximal renal tubule. The association of FHHt with epilepsy leads us to speculate that the raised serum K in susceptible subjects may cause a rise in CSF K, and extracellular cerebral K, leading to epilepsy.

Novel potassium binders to optimize RAASi therapy in heart failure: A systematic review and meta-analysis.

AIMS: Hyperkalemia often occurs among heart failure (HF) patients, particularly when treated with renin-angiotensin-aldosterone system inhibitors (RAASi). Even modest potassium levels variations raise the risk of mortality and prompt patients to discontinue disease-modifying treatment, as RAASi. Novel potassium binders (NPB), patiromer and sodium zirconium cyclosilicate, are effective in reducing potassium levels and are approved for the treatment of hyperkalemia in HF, but whether their use results in a real optimization of HF treatment remains to be seen. The aim of the present meta-analysis was to assess the efficacy of NPB on the optimization of RAASi therapy in HF patients. METHODS AND RESULTS: PubMed, Web of Science and Clinicaltrial.gov were searched without restrictions from inception to 06 August 2022 to identify valuable articles. The studies that met the inclusion criteria were analyzed. The prespecified primary outcome was the optimization of RAASi therapy in HF patients, defined as the proportion of patients on RAASi at the end of follow-up. Secondary outcomes were hyperkalemia events, reduction in potassium levels, and adverse drugs reactions. Six studies with a total of 1390 patients were included. NPB improved RAASi therapy optimization in HF by 14% (95% CI: 4-26%), decreased hyperkalemia events by 29% (95% CI: 55-92%), and reduced potassium levels by 0.31 mEq/L (95% CI: 0.18-0.44) compared to placebo, maintaining a good safety profile. CONCLUSION: NPB are effective in allowing RAASi therapy optimization in patients affected by HF, in reducing hyperkalemia events and potassium levels. SYSTEMATIC REVIEW REGISTRATION: CRD42022351811 URL: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=351811.

Potassium levels in women with polycystic ovary syndrome using spironolactone for long-term.

OBJECTIVE: Spironolactone (SPL) has been used to manage hyperandrogenic manifestations in women with polycystic ovary syndrome (PCOS), but data on the risk of hyperkalemia in this population are scarce. The aim of this study was to evaluate the incidence of hyperkalemia in women with PCOS using SPL in the long term. DESIGN: Single-centre retrospective study. PATIENTS: Inclusion and analysis of 98 treatment periods in 78 women with PCOS (20 of whom were duplicates, returning after treatment interruption for a mean of 38 months) who received SPL for a minimum of 12 months and had at least three measurements of potassium levels over time. MEASUREMENTS: Clinical and hormonal profiles before and during SPL treatment. RESULTS: Mean age was 29.1 (SD: 9.6) years, and body mass index was 32.2 (SD: 8.1) kg/m². Nine patients had diabetes, and 22 had prediabetes. SPL was used in combination with combined oral contraceptive pills in 55 participants and progestin-only pills/long-acting reversible contraception in 28; metformin was added in 35, and angiotensin-converting enzyme inhibitors/angiotensin receptor blockers in 15. Median SPL dose was 100 (range: 50-150) mg. A total of 327 serum potassium measurements were obtained (84 pre-exposure and 243 postexposure). Four potassium measurements were above the reference range before exposure and 19 during exposure. All potassium measurements above the reference range during follow-up were classified as mild hyperkalemia (5.1-5.5 mEq/L). CONCLUSIONS: The present findings suggest that women with PCOS, without kidney or heart disease, using SPL combined with hormonal contraception for managing clinical hyperandrogenism have a low incidence of hyperkalemia and well-tolerated minor adverse effects.

Mineralocorticoid receptor antagonist treatment in patients with renal insufficiency and the associated risk of hyperkalemia and death.

OBJECTIVES: Mineralocorticoid receptor antagonist (MRA) treatment is kidney protective but not recommended to patients with advanced renal failure due to the risk of hyperkalemia and death. This study aimed to examine the impact of MRA treatment in patients with chronic kidney disease on risk of hyperkalemia and subsequent mortality. METHODS: Rates of hyperkalemia were compared across strata of estimated glomerular filtration rate (eGFR) and MRA treatment based on cox regression using a nested case-control framework with 1 : 4 matching of patients with hyperkalemia (K + ≥6.0 mmol/l) with controls from the Danish general population on age, sex, diabetes, and hypertension. Risk of subsequent 30-day mortality was assessed in a cohort study with comparisons across strata of eGFR and MRA treatment based on multiple Cox regression. RESULTS: Thirty-two thousand four hundred twenty-six cases with hyperkalemia were matched with 127 038 controls. MRA treatment was associated with an increased rate of hyperkalemia with hazard ratios [95% confidence interval (95% CI)] of 8.28 (7.78-8.81), 5.12 (4.67-5.62), 3.58 (3.23-3.97), and 1.89 (1.60-2.23) in patients with eGFR at least 60, 45-59, 30-44, and less than 30 ml/min/1.73 m 2 , respectively (Reference: No MRA).However, MRA-exposed patients had a lower 30-day mortality risk following hyperkalemia with absolute risks (95% CI) of 29.3% (27.8-31.1), 20.3% (18.7-22.4), 19.5% (17.9-21.7), and 19.7% (17.4-22.5) compared to 39.8% (38.8-40.8), 32.0% (30.7-33.1), 28.8% (27.5-31.2), and 22.5% (21.4-23.4) in patients without MRA exposure in patients with GFR at least 60, 45-59, 30-44, and less than 30 ml/min/1.7 3m 2 , respectively. CONCLUSION: MRA treatment was associated with an increased rate of hyperkalemia but decreased risk of subsequent 30-day mortality across all stages of renal impairment.

Overview of research progress on the association of dietary potassium intake with serum potassium and survival in hemodialysis patients, does dietary potassium restriction really benefit hemodialysis patients?

For the general population, increasing potassium intake can reduce the incidence of cardiovascular and cerebrovascular diseases. However, since hyperkalemia is a common and life-threatening complication in maintenance hemodialysis patients, which can increase the risk of malignant arrhythmia and sudden death, the current mainstream of management for hemodialysis patients is dietary potassium restriction in order to prevent hyperkalemia. Hemodialysis patients are usually advised to reduce dietary potassium intake and limit potassium-rich fruits and vegetables, but there is limited evidence to support this approach can reduce mortality and improve quality of life. There is still no consistent conclusion on the association between dietary potassium intake and serum potassium and survival in hemodialysis patients. According to the current small observational studies, there was little or even no association between dietary potassium intake and serum potassium in hemodialysis patients when assurance of adequate dialysis and specific dietary patterns (such as the plant-based diet mentioned in the article) are being followed, and excessive dietary potassium restriction may not benefit the survival of hemodialysis patients. Additionally, when assessing the effect of diet on serum potassium, researchers should not only focus on the potassium content of foods, but also consider the type of food and the content of other nutrients. However, more large-scale, multi-center clinical trials are required to provide high-quality evidence support. Besides, further research is also needed to determine the optimal daily potassium intake and beneficial dietary patterns for hemodialysis patients.

Cost-effectiveness analysis of sodium zirconium cyclosilicate for treating hyperkalemia among Chinese patients.

Objectives: Hyperkalemia most commonly develops in chronic kidney disease (CKD) or heart failure (HF) patients. Sodium zirconium cyclosilicate (SZC) is a new selective potassium (K+) binder for treating hyperkalemia. The aim of this study was to evaluate the cost-effectiveness of SZC vs. usual care for the treatment of hyperkalemia among CKD patients or HF patients in China. Methods: Individual patient microsimulation models were constructed to simulate a CKD cohort until the initiation of renal replacement therapy (RRT) and a HF cohort across the lifetime horizon. K+ levels were based on two phase 3 clinical trials. Health state utility and event incidence rates were retrieved from literature. Drug costs and healthcare utilization costs were obtained from negotiated price, literature, and expert interviews. Costs and quality-adjusted life-years (QALYs) were both discounted at 5%. The main outcomes were overall costs, QALYs, and incremental cost-effectiveness ratio (ICER). The willingness-to-pay (WTP) threshold in China is CNY 80,976-242,928/QALY, which is one to three times the gross domestic product per capita. Sensitivity analyses were performed to characterize the models' uncertainty. Results: In the HF cohort, the base case results revealed that SZC was associated with 2.86 QALYs and the total cost was CNY 92671.58; usual care was associated with 1.81 QALYs and CNY 54101.26. In the CKD cohort, SZC was associated with 3.23 QALYs and CNY 121416.82 total cost; usual care was associated with 2.91 QALYs and CNY 111464.57. SZC resulted in an ICER of CNY 36735.87/QALY for the HF cohort and CNY 31181.55/QALY for the CKD cohort, respectively. The one-way and probability sensitivity analyses found that the results were robust. Conclusion: SZC is a cost-effective treatment compared to usual care in HF and CKD patients. SZC is an important novel treatment option for managing patients with hyperkalemia in China.

[Hyponatremia and Electrolyte Disorders in Cancer Patients].

Onconephrology is a rising and rapidly expanding field of medicine in which nephrology and oncology meet each other. Besides multidisciplinary meetings, oncologists and nephrologists often discuss on timing of the treatment, dosage, and side effects management. Cancer patients often encounter different electrolyte disorders. They are mostly secondary to the tumor itself or consequences of its treatment. In the last years, the great efforts to find new therapies like targeted, immune, and cell-based led us to many new side effects. Hyponatremia, hypokalemia, hyperkalemia, hypercalcemia, and hypomagnesemia are among the most common electrolyte disorders. Data have shown a worse prognosis in patients with electrolytic imbalances. Additionally, they cause a delay in chemotherapy or even an interruption. It is important to diagnose promptly these complications and treat them. In this review, we provide a special focus on hyponatremia and its treatment as the most common electrolytes disorder in cancer patients, but also on newly described cases of hypo- and hyperkalemia and metabolic acidosis.

Practical patient care appraisals with use of new potassium binders in heart failure and chronic kidney diseases.

Hyperkalaemia is a life-threatening condition leading to significant morbidity and mortality. It is common in heart failure and in chronic kidney disease (CKD) patients due to the diseases themselves, which often coexist, the high co-presence of diabetes, the fluctuations in renal function, and the use of some drugs [i.e. renin-angiotensin-aldosterone system (RAAS) inhibitors]. Hyperkalaemia limits their administration or uptitration, thus impacting on mortality. New K + binders, namely patiromer and sodium zirconium cyclosilicate (ZS-9), are an intriguing option to manage hyperkalaemia in heart failure and/or CKD patients, both to reduce its fatal effects and to let clinicians uptitrate RAAS inhibition. Even if their real impact on strong outcomes is still to be determined, we hereby provide a practical approach to favour their use in routine clinical practice in order to gain the correct confidence and provide an additive tool to heart failure and CKD patients' wellbeing. New trials are welcome to fill the gap in knowledge.

Hematological differentiation of bladder rupture and complete/partial urethral obstruction in castrated Hanwoo (Korean indigenous cattle) with urolithiasis.

This case report describes the hematological and radiological examination of urinary bladder rupture and complete urethral obstruction. associated with urolithiasis in Hanwoo. Hyponatremia, hypochloremia, azotemia, and hyperglycemia were observed in both urethral obstruction and urinary bladder rupture. However, cattle with urethral obstruction showed hyperkalemia and mild hyperglycemia, whereas cattle with bladder rupture showed marked hyperglycemia and normal potassium levels. In ultrasonography, the urethral obstruction showed a dilated bladder with a thick bladder wall. In contrast to previous literature, in this study, severe electrolyte changes such as severe hyponatremia, hypochloremia, and hyperkalemia occurred in a case of complete urethral obstruction.

Acute flaccid paralysis due to multifactorial hyperkalaemia.

A male patient in his late 30s with a history of Lynch syndrome and colorectal cancer relapse, which recently started chemotherapy, was admitted to the emergency department with acute lower limb weakness that had progressed to all limbs and resulted in complete flaccid paresis with general areflexia. Blood tests showed severe hyperkalaemia, severe acute kidney injury and hyperuricaemia. Ultrasound showed bilateral hydronephrosis due to pelvic mass obstruction. Hyperkalaemia correction measurements were started as well as rasburicase with the assumption of tumour lysis syndrome and postrenal kidney injury. The patient showed a favourable clinical response with complete return of limb movement in the following hours and progressive recovery of renal function in the following days. This case highlights the need for prompt diagnosis and correction of severe hyperkalaemia, and its multiple possible causes, as it can lead to acute flaccid paralysis and a fatal outcome.

Brugada syndrome uncovered in patient with pseudohypoaldosteronism due to hyperkalaemia.

Brugada syndrome is a rare sodium channelopathy that predisposes to an increased risk of malignant arrythmias and sudden cardiac death. Previous studies have reported that metabolic disturbances can uncover a Brugada ECG pattern. Given the risk of malignant arrhythmias, it is important to correctly diagnose and treat Brugada syndrome. We report a case of Brugada syndrome uncovered by hyperkalaemia precipitated in a patient with pseudohypoaldosteronism.

Short-term prognosis of changes in plasma potassium following an episode of hyperkalaemia in patients with chronic heart failure.

BACKGROUND/AIM: There is an increasing prevalence of chronic heart failure (HF). It is well known that patients with HF and disturbances in the potassium level have an increased mortality risk. The aim of this study was to investigate the prognosis of a second plasma-potassium measurement after an episode with hyperkalaemia on short-term mortality in patients with chronic HF. METHODS AND RESULTS: From Danish national registers, 2,339 patients with chronic HF and hyperkalaemia (>4.6 mmol/L) at first potassium measurement within 14-365 days from concomitant treatment were identified. To be included, a second measurement was required within 6-30 days subsequent to the first measurement and the 60-day mortality was observed. Based on the second measurement, the patients were divided into five groups: <3.5 mmol/L (n = 257), 3.5-4.0 mmol/L (n = 709), 4.1-4.6 mmol/L (n = 1,204, reference), 4.7-5.0 mmol/L (n = 89) and >5.0 mmol/L (n = 80). To assess all-cause and cardiovascular mortality, we used the Cox regression model. The multivariable analysis showed that patients with potassium concentrations <3.5 mmol/L (hazard ratio (HR): 3.03; 95% CI: 2.49-3.70) and 3.5-4.0 mmol/L (HR: 1.81; 95% CI: 1.54-2.14) had a worse prognosis compared to the reference. We observed similar results when calculating the risk of cardiovascular mortality. A restricted cubic spline curve showed a U-shaped relationship between plasma-potassium and all-cause mortality. CONCLUSION: Patients with chronic HF and hyperkalaemia who became hypokalaemic after 6-30 days were associated with a higher 60-day all-cause and cardiovascular mortality compared to the reference. This also applied for patients with low normal potassium concentrations (3.5-4.0 mmol/L).