Evaluating the potential of daily intake of polystyrene microplastics via drinking water in inducing PCOS and its ovarian fibrosis progression using female zebrafish.

Polystyrene microplastics, extensively considered endocrine disrupting chemicals, disturb the reproductive system of living organisms. Polycystic ovary syndrome (PCOS), the reproductive endocrinopathy, is longstanding concern due to its eternal impacts as reproductive disorder and infertility. Despite several reports in reproductive and endocrine toxicity, there is inadequate literature regarding the daily intake of polystyrene-microplastics via drinking water in causing PCOS and leading to ovarian fibrosis in long-term. The present study investigated whether daily consumption of polystyrene-microplastics at doses equivalent to human exposure can cause PCOS and progress to ovarian fibrosis, using female zebrafish as model. Resembling letrozole-PCOS zebrafish model, daily intake of polystyrene-microplastics displayed hallmark PCOS pathophysiology; like excess body weight and %Gonadosomatic index, decreased Follicle Stimulating Hormone and ß-estradiol, increased Luteinising Hormone, brain and ovarian Testosterone (39.3% and 75% respectively). Correspondingly, ovarian histology revealed more developing (stage I and II) oocytes and less mature oocytes alongwith cystic lesions; like follicular membrane disorganization, zona pellucida invagination, theca hypertrophy, basophilic granular accumulation and oocyte buddings. Lipid deposition in intestinal and ovarian tissues was evidenced and increased fasting blood glucose manifesting insulin resistance. The expression of PCOS biomarkers (tox3, dennd1a, fem1a) was significantly disturbed. Polystyrene microplastics played vital role in inducing PCOS further enhancing oxidative stress, which positively influences inflammation and aggravate ovarian mitophagy, shedding light on its ability to harshen PCOS into ovarian fibrosis, which is characterized by collagen deposition and upregulation of pro-fibrogenic biomarker genes. These findings illustrate the potential of daily microplastics intake via drinking water in triggering PCOS and its progression to ovarian fibrosis.

The combined exposure of polystyrene microplastics and high-fat feeding affects the intestinal pathology damage and microbiome in zebrafish.

The pervasive utilization of plastics and their integration into ecosystems has resulted in significant environmental issues, particularly the pollution of microplastics (MPs). In aquaculture, high-fat feed (HFD) is frequently employed to enhance the energy intake and economic fish production. This study utilized zebrafish as a model organism to investigate the impact of concurrent exposure to HFD and MPs on fish intestinal pathology damage and intestinal microbiome. The experimental design involved the division of zebrafish into two groups: one receiving a normal diet (ND) and the other receiving HFD. The zebrafish were exposed to a control group, as well as polystyrene (PS) MPs of varying sizes (5 and 50 µm). Histopathological examination revealed that the combination of 5 µm MPs and HFD resulted in the most significant damage to the zebrafish intestinal tract. Furthermore, gut microbiome assays indicated that exposure to MPs and HFD altered the composition of the gut microbiome. This study demonstrates that in aquaculture, the issue of HFD must be considered alongside concerns about MPs contamination, as both factors appear to have a combined effect on the intestinal pathology damage and intestinal microbiome. The findings of this research offer valuable insights for the improvement of fish farming practices.

Calcium polystyrene sulfonate-induced rectal ulcer causing E. coli native-valve infective endocarditis.

Escherichia coli-associated native-valve infective endocarditis is a rare disease that affects elderly patients with underlying risk factors such as diabetes mellitus, malignancy, and renal failure. Long-term use of calcium polystyrene sulfonate is a potential risk factor for gastrointestinal mucosal damage or even colorectal ulcers. Herein, we describe a fatal case of a 66-year-old Japanese man with diabetes mellitus and renal failure who was prescribed calcium polystyrene sulfonate (CPS) for 11 years and developed a CPS-induced rectal ulcer, leading to E. coli native-valve infective endocarditis. The patient was admitted to our hospital due to acute-onset impaired consciousness. As a result of the systemic investigation, he was diagnosed with E. coli bacteremia accompanied by multiple cerebral infarctions and an acute hemorrhagic rectal ulcer. Transesophageal echocardiography revealed a 20-mm vegetative structure on the mitral valve, resulting in a final diagnosis of E. coli-associated infective endocarditis. After rectal resection, mitral valve replacement surgery was performed; however, the patient died shortly after surgery. Pathological findings of the resected rectum showed deposition of a basophilic crystalline material suggesting the presence of CPS. Our case highlights the potential risk of colorectal ulcers in a long-term CPS user, which can trigger bacterial translocation and endocarditis as fatal complications.

[What's new in hyperkalemia management?] / Nouveautés dans la prise en charge de l'hyperkaliémie.

Hyperkalemia is common in everyday clinical practice, and is a major risk factor for mortality. It mainly affects patients with chronic renal failure (CKD), diabetes or receiving treatment with inhibitors of the renin-angiotensin-aldosterone system (iRAAS). Therapeutic management aims not only to avoid the complications of hyperkalemia, but also to avoid discontinuation of cardio- and nephroprotective treatments such as iRAAS. The use of polystyrene sulfonate, widely prescribed, is often limited by patient acceptability. Recent data have cast doubt on its safety, particularly in terms of digestive tolerance. Two new potassium exchange molecules have appeared on the market: patiromer and zirconium sulfonate. Their value in clinical practice, and their acceptability in the event of prolonged prescription, remain to be demonstrated. The combination of a thiazide diuretic or an inhibitor of the sodium-glucose cotransporter type 2 (iSGLT2) with iRAAS therapy in CKD, may also improve control of kalemia. At present, there are no recommendations for the positioning of the various hypokalemic treatments. The choice of these treatments must be adapted to the patient's pathologies and consider the other expected effects of these molecules.

Evaluation of the introduction of novel potassium binders in routine care; the Stockholm CREAtinine measurements (SCREAM) project.

BACKGROUND: The pharmacological management of hyperkalemia traditionally considered calcium or sodium polystyrene sulfonate and, since recently, the novel binders patiromer and sodium zirconium cyclosilicate. We evaluated their patterns of use, duration of treatment and relative effectiveness/safety in Swedish routine care. METHODS: Observational study of adults initiating therapy with sodium polystyrene sulfonate or a novel binder (sodium zirconium cyclosilicate or patiromer) in Stockholm 2019-2021. We quantified treatment duration by repeated dispensations, compared mean achieved potassium concentration within 60 days, and potential adverse events between treatments. RESULTS: A total of 1879 adults started treatment with sodium polystyrene sulfonate, and 147 with novel binders (n = 41 patiromer and n = 106 sodium zirconium cyclosilicate). Potassium at baseline for all treatments was 5.7 mmol/L. Sodium polystyrene sulfonate patients stayed on treatment a mean of 61 days (14% filled ≥3 consecutive prescriptions) compared to 109 days on treatment (49% filled ≥3 prescriptions) for novel binders. After 15 days of treatment, potassium similarly decreased to 4.6 (SD 0.6) and 4.8 (SD 0.6) mmol/L in the sodium polystyrene sulfonate and novel binder groups, respectively, and was maintained over the 60 days post-treatment. In multivariable regression, the odds ratio for novel binders (vs sodium polystyrene sulfonate) in reaching potassium ≤ 5.0 mmol/L after 15 days was 0.65 (95% CI 0.38-1.10) and after 60 days 0.89 (95% CI 0.45-1.76). Hypocalcemia, hypokalemia, and initiation of anti-diarrheal/constipation medications were the most-commonly detected adverse events. In multivariable analyses, the OR for these events did not differ between groups. CONCLUSION: We observed similar short-term effectiveness and safety for all potassium binders. However, treatment duration was longer for novel binders than for sodium polystyrene sulfonate.

Maltol attenuates polystyrene nanoplastic-induced enterotoxicity by promoting AMPK/mTOR/TFEB-mediated autophagy and modulating gut microbiota.

The production and application of nanoplastics has been increased during decades, and the enterotoxicity caused by their bioaccumulation has attracted vast attention. Maltol was proved to exert a protective effect on gut damage induced by carbon tetrachloride and cisplatin, indicating its confrontation with nanoplastics-induced intestinal toxicity. To explore the ameliorative effects of maltol on polystyrene nanoplastics (PS)-mediated enterotoxicity and the underlying mechanism, the mice were exposed to PS (100 mg/kg), combining with or without the treatment of maltol treatment at 50 and 100 mg/kg. We found PS exposure caused intestinal barrier damage and enterocyte apoptosis, while lysosomal dysfunction and autophagic substrate degradation arrest in enterocytes of mice were also observed. In addition, PS exacerbated the disturbance of the intestinal microbial community, affected the abundance of lysosome and apoptosis-related bacterial genes, and decreased the number of known short-chain fatty acid (SCFA) producing bacteria. However, those alterations were improved by the maltol treatment. Maltol also protected the human intestinal Caco-2 cells from PS-induce damages. Mechanistic studies showed maltol promoted TFEB nuclear translocation through the AMPK/mTOR signaling pathway to restore lysosomal function and reduce autophagy dependent apoptosis. The findings in the present work might help to elucidate the potential molecular mechanisms of PS-induced enterotoxicity. For the first time to our knowledge, the protective effect of maltol on PS-induced intestinal injury was studied from multiple perspectives, which provided a potential therapeutic approach for diseases caused by environmental pollution.

Effects of styrene monomer on a mouse model of atopic dermatitis.

Aim: Styrene monomer (SM) is a basic chemical used as a raw material for polystyrene and unsaturated polyester resins and in the production of synthetic resins, synthetic rubbers, paints, and adhesives. To date, it is unclear whether SM is associated with the aggravation of atopic dermatitis. The aim was to investigate the effects of SM on atopic dermatitis-like skin lesions induced by mite allergen in NC/Nga mice.Methods: Male mice were injected intradermally with mite allergen on their right ears. In the presence of an allergen, SM (3.5 or 350 µg/animal/week) was administered by intraperitoneal injection. We evaluated clinical scores, ear thickening, histologic findings, and the protein expressions of cytokines and chemokines.Results: Macroscopic and microscopic examinations demonstrated that exposure to SM at a dose of 3.5 µg caused an exacerbation of atopic dermatitis-like skin lesions related to mite allergen. These changes were consistent with the level of histamine in the ear tissue as an overall trend. In contrast, 350-µg SM did not show significant enhancement effects.Conclusion: These results indicate that SM exacerbated atopic dermatitis-like skin lesions at hundred-fold lower levels than the level that causes no observed adverse effects as determined by histologic changes in rodent livers. SM could be at least partly responsible for the recent increase in atopic dermatitis.Impact statementStyrene monomer (SM) is classified as an International Agency for Research on Cancer group 2B carcinogen and includes neurotoxicity and respiratory disorders. However, the effects of SM as a chemical substance on existing allergic pathophysiology have not been elucidated yet. This study demonstrated that SM exacerbated murine atopic dermatitis-like skin lesions at hundred-fold lower levels than the level that causes no observed adverse effects as determined by histologic changes in rodent livers, which was concomitant with the local level of histamine. These data hasten a need for comprehensive research to clarify the chemical pollutants' effects of doses much lower than NOAEL on vulnerable pathophysiologies such as allergy/atopy.

Effects of Calcium Polystyrene Sulfonate Formulation Change from Dry Syrup to Oral Solution in Patients with Chronic Kidney Disease.

Calcium polystyrene sulfonate, a cation exchange resin preparation, is used to treat hyperkalaemia. The effects of switching from dry syrup to oral solution forms have been rarely evaluated. We investigated changes in serum potassium levels, incidence of adverse events, and patients' perception and satisfaction associated with the change in calcium polystyrene sulfonate dosage forms from dry syrup to oral solution in chronic kidney disease patients. The study population was comprised of 24 patients. The chronic kidney disease cause, glomerular filtration rate category, and albuminuria category was G4 in 10 cases (41.7%) and G5 in 8 cases (33.3%). No significant difference was observed between groups before and after the change in dosage form. Contrastingly, the ease of intake (P=0.0047), taste (P=0.0056), and satisfaction (P<0.001) indicated positive significant improvements. Changing the calcium polystyrene sulfonate dosage form from dry syrup to oral solution in patients with chronic kidney disease improved patient satisfaction while maintaining efficacy and safety. For patients in whom weight gain is not a problem, we recommend changing the dosage form from dry syrup to oral solution for calcium polystyrene sulfonate.

Exploring co-dispensed drug use in patients on sevelamer or polystyrene sulfonate to identify potential novel binding interactions: a cross sectional in silico study : Potential novel binding interactions with resins.

Background Sevelamer and polystyrene sulfonate are used for treating hyperphosphatemia and hyperkalaemia in chronic kidney disease patients. Because of their binding properties, these resins potentially bind other drugs in the gastrointestinal tract, thereby decreasing their bioavailability and clinical effectiveness. Aim The aim of this study was to explore co-dispensed drug use in patients on sevelamer or polystyrene sulfonate to identify potential novel binding interactions. Method In this in silico study, the 100 drugs most frequently co-dispensed with sevelamer/polystyrene sulfonate in the period 2000-2018 were extracted from the University Groningen IADB.nl database. Drugs dispensed to < 5% of patients, drugs not orally administered, drugs administered once daily before bedtime and drugs for which information on binding interactions with sevelamer or polystyrene was already available were excluded. The likelihood of an interaction (yes or no) of the included drugs was assessed based on pKa- and Log P values. For sevelamer, drugs with a pKa (acid) between 1.5 and 7.4 and or a Log P value > 2.0 were identified as potential interacting drug. For polystyrene sulfonate, drugs with a pKa (base) > 1.5 were identified as potential interacting drug. Results Of the top 100 drugs most frequently co-dispensed with sevelamer/polystyrene sulfonate, 22 and 27 potentially clinically relevant new interacting drugs were identified for sevelamer and polystyrene sulfonate respectively. Conclusion Several potentially relevant novel binding interactions for sevelamer and polystyrene sulfonate were identified based on dispensing data and assessment of chemical properties for which further interaction research is warranted.

Polystyrene microplastic particles induce endothelial activation.

Due to its increasing production, durability and multiple applications, plastic is a material we encounter every day. Small plastic particles from the µm to the mm range are classified as microplastics and produced for cosmetic and medical products, but are also a result of natural erosion and decomposition of macroplastics. Although being omnipresent in our environment and already detected in various organisms, less is known about the effects of microplastics on humans in general, or on vascular biology in particular. Here we investigated the effects of carboxylated polystyrene microplastic particles (PS, 1 µm) on murine endothelial and immune cells, which are both crucially involved in vascular inflammation, using in vitro and in vivo approaches. In vitro, PS induced adhesion molecule expression in endothelial cells with subsequent adhesion of leukocytes both under static and flow conditions. In monocytic cells, PS enhanced pro-inflammatory cytokine expression and release. Accordingly, administering mice with PS led to enhanced aortic expression of cytokines and adhesion molecules. Furthermore, we identified neutrophils as the PS-clearing blood leukocyte population. The findings from this study for the first time indicate polystyrene microplastic as a new environmental risk factor for endothelial inflammation.

Long-Term Effects of Polystyrene Nanoplastics in Human Intestinal Caco-2 Cells.

The increasing presence of micro- and nanoplastics (MNPLs) in the environment, and their consequent accumulation in trophic niches, could pose a potential health threat to humans, especially due to their chronic ingestion. In vitro studies using human cells are considered pertinent approaches to determine potential health risks to humans. Nevertheless, most of such studies have been conducted using short exposure times and high concentrations. Since human exposure to MNPLs is supposed to be chronic, there is a lack of information regarding the potential in vitro MNPLs effects under chronic exposure conditions. To this aim, we assessed the accumulation and potential outcomes of polystyrene nanoparticles (PSNPs), as a model of MNPLs, in undifferentiated Caco-2 cells (as models of cell target in ingestion exposures) under a relevant long-term exposure scenario, consisting of eight weeks of exposure to sub-toxic PSNPs concentrations. In such exposure conditions, culture-media was changed every 2-3 days to maintain constant exposure. The different analyzed endpoints were cytotoxicity, dysregulation of stress-related genes, genotoxicity, oxidative DNA damage, and intracellular ROS levels. These are endpoints that showed to be sensitive enough in different studies. The obtained results attest that PSNPs accumulate in the cells through time, inducing changes at the ultrastructural and molecular levels. Nevertheless, minor changes in the different evaluated genotoxicity-related biomarkers were observed. This would indicate that no DNA damage or oxidative stress is observed in the human intestinal Caco-2 cells after long-term exposure to PSNPs. This is the first study dealing with the long-term effects of PSNPs on human cultured cells.

Risk of Intestinal Necrosis With Sodium Polystyrene Sulfonate: A Systematic Review and Meta-analysis.

BACKGROUND: Reports of severe gastrointestinal side effects associated with sodium polystyrene sulfonate (SPS), particularly intestinal necrosis, have led some to recommend costlier alternative medications. No prior systematic review has included studies with controls reporting intestinal necrosis rates associated with SPS. METHODS: A systematic literature search was conducted using Cochrane Library, Embase, Medline, Google Scholar, PubMed, Scopus, and Web of Science Core Collection from database inception through October 4, 2020. We included any clinical trial, cohort, or case-control study reporting an association between SPS and intestinal necrosis or severe gastrointestinal side effects. RESULTS: Six studies including 26,716 patients treated with SPS with controls met inclusion criteria. The pooled odds ratio (OR) of intestinal necrosis was 1.43 (95% CI, 0.39-5.20). The pooled hazard ratio (HR) for intestinal necrosis from the two studies that performed survival analysis was 2.00 (95% CI, 0.45-8.78). The pooled HR for the composite outcome of severe gastrointestinal adverse events was 1.46 (95% CI, 1.01-2.11). CONCLUSION: Based on our review of six studies, the risk of intestinal necrosis with SPS is not statistically greater than controls, although there was a statistically significantly increased risk for the composite outcome of severe gastrointestinal side effects based on two studies. Because of the risk of bias from potential confounding and selective reporting, the overall strength of evidence to support an association between SPS and intestinal necrosis or other severe gastrointestinal side effects is low. PROSPERO registration CRD42020213119.

Novel Characterization of Constipation Phenotypes in ICR Mice Orally Administrated with Polystyrene Microplastics.

Indirect evidence has determined the possibility that microplastics (MP) induce constipation, although direct scientific proof for constipation induction in animals remains unclear. To investigate whether oral administration of polystyrene (PS)-MP causes constipation, an alteration in the constipation parameters and mechanisms was analyzed in ICR mice, treated with 0.5 µm PS-MP for 2 weeks. Significant alterations in water consumption, stool weight, stool water contents, and stool morphology were detected in MP treated ICR mice, as compared to Vehicle treated group. Also, the gastrointestinal (GI) motility and intestinal length were decreased, while the histopathological structure and cytological structure of the mid colon were remarkably altered in treated mice. Mice exposed to MP also showed a significant decrease in the GI hormone concentration, muscarinic acetylcholine receptors (mAChRs) expression, and their downstream signaling pathway. Subsequent to MP treatment, concentrations of chloride ion and expressions of its channel (CFTR and CIC-2) were decreased, whereas expressions of aquaporin (AQP)3 and 8 for water transportation were downregulated by activation of the mitogen-activated protein kinase (MAPK)/nuclear factor (NF)-κB signaling pathway. These results are the first to suggest that oral administration of PS-MP induces chronic constipation through the dysregulation of GI motility, mucin secretion, and chloride ion and water transportation in the mid colon.

Effects of microplastics (MPs) and tributyltin (TBT) alone and in combination on bile acids and gut microbiota crosstalk in mice.

Microplastics (MPs) and tributyltin (TBT) are both potential environmental pollutants that enter organisms through the food chain and affect bodily functions. However, the effects and mechanisms of MPs and TBT exposure (especially the co-exposure of both pollutants) on mammals remain unclear. In this study, Ф5µm MPs (5MP) was administered alone or in combination with TBT to investigate the health risk of oral exposure in mice. All three treatments induced inflammation in the liver, altered gut microbiota composition and disturbed fecal bile acids profiles. In addition to decreasing triglyceride (TG) and increasing aspartate aminotransferase (AST) and macrophage-expressed gene 1 (Mpeg1), 5MP induced hepatic cholestasis by stimulating the expression of the cholesterol hydroxylase enzymes CYP8B1 and CYP27A1, and inhibiting multidrug resistance-associated protein 2 and 3 (MRP2, MRP3), and bile-salt export pump (BSEP) to prevent bile acids for entering the blood and bile. Correspondingly, 5MP treatment decreased 7-ketolithocholic acid (7-ketoLCA) and taurocholic acid (TCA), which were positively correlated with decreased Bacteroides and Marvinbryantia and negatively correlated with increased Bifidobacterium. In addition, TBT increased interferon γ (IFNγ) and Mpeg1 levels to induce inflammation, accompanied by decreased 7-ketoLCA, tauro-alpha-muricholic acid (T-alpha-MCA) and alpha-muricholic acid (alpha-MCA) levels, which were negatively related to Coriobacteriaceae_UCG-002 and Bifidobacterium. Co-exposure to 5MP and TBT also decreased TG and induced bile acids accumulation in the liver due to inhibited BSEP, which might be attributed to the co-regulation of decreased T-alpha-MCA and Harryflintia. In conclusion, the administration of 5MP and TBT alone and in combination could cause gut microbiome dysbiosis and subsequently alter bile acids profiles, while the combined exposure of 5MP and TBT weakened the toxic effects of 5MP and TBT alone.

SPS(Kayexalate)/CPS(K-Bind) crystals in the gastrointestinal tract-An experience from a tertiary center.

INTRODUCTION: Kayexalate (Sodium Polystyrene Sulfonate/SPS) and K-bind (Calcium Polystyrene Sulfonate/CPS) are cation exchange resins, commonly used for treatment of hyperkalaemia. SPS/CPS induced injury of the gastrointestinal tract(GIT) is rare, can be potentially life threatening but is under-recognized. This study aims to increase awareness of pathologists and clinicians of this under-reported complication of a drug commonly used to treat hyperkalaemia. MATERIALS: Study population comprised patients with SPS/CPS (Kayexalate or its analogues) crystals identified in gastrointestinal specimens from 2017-2019 at a tertiary care centre. Clinical details, relevant investigations, imaging and endoscopic findings, patient follow up details were obtained from the hospital electronic information system. RESULTS: A total of 10 patients with SPS/ CPS crystals in the GIT were encountered over 2 years. Male to female ratio was 9:1, with mean age 66.5years (range 52-82 years). Eight cases were mucosal biopsies and 2 were resection specimens. Additional pathology (tumours, colonic perforation) was present in 80% of patients. The characteristic morphological appearance of the CPS/SPS crystals on H&E stains were supported by special stains -Periodic acid Schiff(PAS) and Acid fast Bacilli(AFB). In all cases, the treatment history with SPS/CPS for hyperkalaemia was obtained only after the histological examination. Most common etiology of hyperkalaemia encountered was chronic kidney disease(CKD)/ Acute on chronic kidney disease. CONCLUSION: It is important for pathologists to recognise the presence of these crystals especially in small biopsies as early feedback to clinicians can help in appropriate management and avoidance of more serious adverse outcome. To the best of our knowledge, this is the first series of 10 consecutive cases of SPS/CPS crystals encountered in gastrointestinal tract to be reported from India.

Exposure of Human Lung Cells to Polystyrene Microplastics Significantly Retards Cell Proliferation and Triggers Morphological Changes.

Microplastics in the environment produced by decomposition of globally increasing waste plastics have become a dominant component of both water and air pollution. To examine the potential toxicological effects of microplastics on human cells, the cultured human alveolar A549 cells were exposed to polystyrene microplastics (PS-MPs) of 1 and 10 µm diameter as a model of the environmental contaminants. Both sizes caused a significant reduction in cell proliferation but exhibited little cytotoxicity, as measured by the maintenance of cell viabilities determined by trypan blue staining and by Calcein-AM staining. The cell viabilities did not drop below 93% even at concentrations of PS-MPs as high as 100 µg/mL. Despite these high viabilities, further assays revealed a population level decrease in metabolic activity parallel in time with a dramatic decrease in proliferation rate in PS-MP exposed cells. Furthermore, phase contrast imaging of live cells at 72 h revealed major changes in the morphology of cells exposed to microplastics, as well as the uptake of multiple 1 µm PS-MPs into the cells. Confocal fluorescent microscopy at 24 h of exposure confirmed the incorporation of 1 µm PS-MPs. These disturbances at the proliferative and cytoskeletal levels of human cells lead us to propose that airborne polystyrene microplastics may have toxicologic consequences. This is the first report of exposure of human cells to an environmental contaminant resulting in the dual effects of inhibition of cell proliferation and major changes in cell morphology. Our results make clear that human exposure to microplastic pollution has significant consequence and potential for harm to humans.

Adverse gastrointestinal events with sodium polystyrene sulphonate and calcium polystyrene sulphonate use in dialysis patients: a nationwide registry study.

INTRODUCTION: Sodium polystyrene sulphonate (SPS) and calcium polystyrene sulphonate (CPS) are commonly used cation-exchange resins for the treatment and control of hyperkalaemia. However, their use (particularly SPS) has been limited by reports of adverse gastrointestinal (GI) events. The safety of these compounds in patients undergoing dialysis requires larger investigation. AIMS: To study the occurrence of adverse GI events (occlusion, perforation, thrombosis/ischaemia) in the periods of SPS or CPS exposition versus the periods without exposition in dialysis patients. METHODS: Dialysis patients were extracted from the French National Registry and merged with the French hospital discharge database (between 2006 and 2017). For our primary analysis, we used patients who had any claim of SPS use (n = 43 771). Time-varying Cox models, negative binomial regression and pre- versus post-treatment average treatment effects. RESULTS: The mean age was 66 ± 15 years, 37% were female and 92% were undergoing haemodialysis. Over a 1-year follow-up, patients on periods with SPS (on-SPS) did not present an increased risk of adverse GI events versus the periods without SPS (off-SPS):  incidence rate (IR) (per 1000 person years) = 7.4 (6.4-8.7) versus 9.5 (8.1-11.0); adjusted hazard ratio (HR) (95% CI) = 0.81 (0.60-1.09), P = 0.17. Patients exposed to SPS did not experience a higher rate of adverse GI events in the year after SPS initiation versus the year before SPS initiation; P-value for parallel trend = 0.87. Patients on-CPS also did not show an increased risk of adverse GI events versus off-CPS: IR (per 1000 py) = 8.6 (5.1-11.9) versus 7.8 (5.1-11.9); adjusted HR (95% CI) = 0.76 (0.31-1.80), P = 0.52. The rates of adverse GI events in the periods on and off exposure were also similar over a follow-up of 5 years. CONCLUSION: Our large, nationwide study shows that the incidence of adverse GI events in patients undergoing dialysis was low and that neither the use of SPS nor CPS was associated with increased GI events risk.

Kayexalate-induced colitis and rectal stricture.

A 57-year-old man underwent emergency laparoscopic loop colostomy for acute recto-sigmoid obstruction. He was hospitalised 2 months previously, at another facility for diabetic ketoacidosis (DKA) and hyperkalaemia. He had no gastrointestinal symptoms prior to the hospitalisation. Both surgical exploration and intraoperative sigmoidoscopy showed ulcerations of sigmoid colon and proximal rectum with a pinhole stricture in mid-rectum. After ruling out all aetiologies, and due to persistence of the colonic ulcerations on a follow-up colonoscopy, a diagnosis of Crohn's colitis was made, and the patient was started on infliximab and 6-mercaptopurine (6-MP). Six months later, on rereview of all the biopsies, it was noted that a key element of presence of crystals suggestive of Kayexalate on the initial colorectal biopsies was missed. It was later found out that the patient had received rectal Kayexalate for treatment of DKA at the other facility. Hence, infliximab and 6-MP were both discontinued. All the colonoscopies, following the discontinuation of the medications, showed complete resolution of colitis but persistence of the mid-rectum stricture. This was treated with a fully covered metal stent for 12 weeks with only partial improvement of the stricture. He was hence referred for ultra-low anterior resection of rectum and take down of colostomy.