Upper gastrointestinal tract injury in patients receiving kayexalate (sodium polystyrene sulfonate) in sorbitol: clinical, endoscopic, and histopathologic findings

Upper Gastrointestinal Bleeding Secondary to Sodium Polystyrene Sulfonate Use: A Rare Adverse Effect of Commonly Prescribed Treatment

We report a case of a 62-year-old man who was brought in by emergency medical services after a fall and change in mental status. He was found to have severe hyperkalemia, acute kidney injury, and rhabdomyolysis. The hyperkalemia was treated with sodium polystyrene sulfonate (SPS). During hospitalization, he witnessed having black tarry stools along with a significant drop in hemoglobin. Endoscopic evaluation demonstrated nonbleeding large diffuse gastric ulcers with stigmata of recent bleeding, and ulcer biopsy revealed findings consistent with SPS-induced gastric ulceration. No other source of bleeding was localized, suggesting acute upper gastrointestinal bleeding due to SPS mucosal injury.

Comprehensive analysis of sodium polystyrene sulfonate-induced colitis: A systematic review

BACKGROUND

Sodium polystyrene sulfonate (SPS) is commonly prescribed for the management of hyperkalemia, a critical electrolyte imbalance contributing to over 800000 annual visits to emergency departments.

AIM

To conduct a systematic review of documented cases of SPS-induced colitis and assess its associated prognosis.

METHODS

Following the PRISMA-P guidelines, our study employed Medical Subject Headings and Health Sciences Descriptors, skillfully combined using Boolean operators, to conduct comprehensive searches across various electronic databases, including Scopus, Web of Science, MEDLINE (PubMed), BIREME (Biblioteca Regional de Medicina), LILACS (Latin American and Caribbean Health Sciences Literature), SciELO (Scientific Electronic Library Online), Embase, and Opengray.eu. Language criteria were confined to English, Spanish, and Portuguese, with no limitations on the publication date. Additionally, we manually scrutinized the reference lists of retrieved studies. To present our findings, we utilized simple descriptive analysis.

RESULTS

Our search strategy yielded a total of 442 references. After rigorous evaluation, we included 51 references, encompassing 59 documented cases of colitis. Predominant clinical presentations included abdominal pain, observed in 35 (60.3%) cases, and bloating, reported in 18 (31%) cases. The most frequently affected sites of inflammation were the cecum, rectum, and small intestine, accounting for 31%, 25.8%, and 22.4% of cases, respectively. Colonoscopy findings were described in 28 (48.2%) cases, and 29 (50%) of patients required surgical intervention. Among the subset of patients for whom outcome data was available, 39 (67.2%) experienced favorable outcomes, while 12 (20.6%) unfortunately succumbed to the condition. The mean time required for resolution was 36.7 d, with a range spanning from 1 to 120 d.

CONCLUSION

SPS demonstrates the capacity to effectively lower serum potassium levels within 24 h. However, this benefit is not without the risk of bowel injury. Our study highlights the absence of high-quality data pertaining to the incidence of adverse events associated with SPS usage, making it challenging to determine whether the potential risks outweigh the benefits. However, a significant mortality rate related to SPS-induced colitis was noted. Future investigations should prioritize randomized controlled trials with a sufficiently large patient cohort to ascertain the true utility and safety profile of this medication.

Adverse Gastrointestinal Events With Sodium Polystyrene Sulfonate Use in Patients on Maintenance Hemodialysis: An International Cohort Study

Background

There are concerns regarding the gastrointestinal (GI) safety of sodium polystyrene sulfonate (SPS), a medication commonly used in the management of hyperkalemia.

Objective

To compare the risk of GI adverse events among users versus non-users of SPS in patients on maintenance hemodialysis.

Design

International prospective cohort study.

Setting

Seventeen countries (Dialysis Outcomes and Practice Patterns Study [DOPPS] phase 2-6 from 2002 to 2018).

Patients

50 147 adults on maintenance hemodialysis.

Measurements

An adverse GI event defined by a GI hospitalization or GI fatality with SPS prescription compared with no SPS prescription.

Methods

Overlap propensity score-weighted Cox models.

Results

Sodium polystyrene sulfonate prescription was present in 13.4% of patients and ranged from 0.42% (Turkey) to 20.6% (Sweden) with 12.5% use in Canada. A total of 935 (1.9%) adverse GI events (140 [2.1%] with SPS, 795 [1.9%] with no SPS; absolute risk difference 0.2%) occurred. The weighted hazard ratio (HR) of a GI event was not elevated with SPS use compared with non-use (HR = 0.93, 95% confidence interval = 0.83-1.6). The results were consistent when examining fatal GI events and/or GI hospitalization separately.

Limitations

Sodium polystyrene sulfonate dose and duration were unknown.

Conclusions

Sodium polystyrene sulfonate use in patients on hemodialysis was not associated with a higher risk of an adverse GI event. Our findings suggest that SPS use is safe in an international cohort of maintenance hemodialysis patients.

[Drug induced gastro-intestinal tract lesions: A pathologist point of view]

The number of drugs available to clinicians, especially targeted therapies, grows continuously. Some drugs are known to cause frequent digestive adverse effects, which may affect the gastro-intestinal tract in a diffuse or localized manner. Some treatments may leave relatively pathognomonic deposits, but histological lesions of iatrogenic origin are mostly non-specific. The diagnostic and etiological approach is often complex because of these non-specific aspects and also because (1) a single type of drug may cause different histological lesions, (2) different drugs may cause identical histological lesions, (3) the patient may receive different drugs, and (4) drug-induced lesions may mimic other pathological entities such as inflammatory bowel disease, celiac disease, or graft versus host disease. The diagnosis of iatrogenic gastrointestinal tract injury therefore requires close anatomic-clinical correlation. The iatrogenic origin can only be formally established if the symptomatology improves when the incriminating drug is stopped. This review aims to present the different histological patterns of gastrointestinal tract iatrogenic lesions, the potentially incriminate drugs, as well as the histological signs to look for in order to help the pathologist to distinguish an iatrogenic injury from another pathology of the gastrointestinal tract.

Hyperkalemia and the Use of New Potassium Binders a Single Center Experience from Vestfold Norway (The PotBind Study)

Purpose

Hyperkalemia is a common metabolic complication of chronic kidney disease (CKD) and is associated with several serious adverse events. We aimed to treat/prevent hyperkalemia using the new of potassium-binders, allowing maintained renin-angiotensin-aldosterone system inhibitors (RAASi) treatment in proteinuric CKD and/or congestive heart failure (CHF) patients.

Patients and Methods

We conducted a retrospective cohort study in long-term users of potassium binders for chronic hyperkalemia. Patients aged 18 years and older, treated with potassium-binders and who met the reimbursement criteria and indication for RAASi treatment were included.

Results

Fifty-seven percent of the patients were males and mean age was 65 years. During the study period, no patients were admitted to hospital due to hyperkalemia after initiation of potassium binders. Potassium maximum values were significantly lower after treatment. Few patients reported major side effects, and discontinuation was mostly due to normokalemia. We found no significant changes in bicarbonate, serum creatinine or GFR stage after starting potassium binder treatment. All patients on RAASi treatment before initiating potassium-binders were retained on RAASi treatment.

Conclusion

New potassium binders in clinical practice are an easy and safe treatment with few side effects and good tolerance, that significantly lowers the risk of hyperkalemia. Furthermore, and most importantly, patients can be maintained on RAASi treatment.

Esophageal Pseudotumor Secondary to Treatment with a Potassium Binder Resin: A Case of Severe Esophagitis Mimicking a Malignancy

Background. Sodium polystyrene sulfonate is a resin used to treat hyperkalemia. Colonic mucosal injury, intestinal ischemia, necrosis, and perforation have been widely reported in the literature, but few cases have reported upper gastrointestinal injury and identify the endoscopic features. Case Presentation. We describe a case of an 83-year-old male, with no prior esophageal symptoms, who developed dysphagia after being treated with sodium polystyrene sulfonate for hyperkalemia. Endoscopic features consistent with severe esophagitis and a mass in the lower esophagus mimicking a malignancy were found, and pathology confirmed resin-induced esophagitis. Discussion. The identification of basophilic crystals in the epithelium with surrounding inflammation is a hallmark of sodium polystyrene sulfonate-induced mucosal injury. Several direct and indirect mechanisms by which SPS may cause mucosal injury have been identified. Prolonged stasis of crystals in the lumen has the potential of developing erosions and ultimately necrosis. The internalization of these crystals to the underlying intestinal mucosa with the combination of the inflammatory response may give an appearance of a luminal mass that can mimic a malignancy. Recognizing the wide-ranging endoscopic findings of resin-induced mucosal injury in the esophagus is fundamental to consider a potential side effect of sodium polystyrene sulfonate. The use of this resin should be avoided in patients with suspected esophageal motility disorder.

New Kids on the Block

CONTEXT.—

With the increasing development and use of iatrogenic agents, pathologists are encountering more novel foreign materials in retrieved gastrointestinal specimens. These colorful and unusual-appearing foreign materials can pose a diagnostic dilemma to those unaware of their morphology, especially if the relevant clinical history is lacking.

OBJECTIVE.—

To discuss the histopathologic features, clinical scenarios and significance, and differential diagnosis of relatively recently described, yet quickly expanding, family of iatrogenic agents that can present as foreign materials in gastrointestinal specimens-pharmaceutical fillers (crospovidone and microcrystalline cellulose), submucosal lifting agents (Eleview and ORISE), lanthanum carbonate, hydrophilic polymers, OsmoPrep, yttrium 90 microspheres (SIR-Sphere and TheraSphere), and resins (sodium polystyrene sulfonate, sevelamer, and bile acid sequestrants).

DATA SOURCES.—

We collate the findings of published literature, including recently published research papers, and authors' personal experiences from clinical sign-out and consult cases.

CONCLUSIONS.—

Correct identification of these iatrogenic agents is important because the presence of some novel agents can explain the histopathologic findings seen in the background specimen, and specific novel agents can serve as diagnostic clues to prompt the pathologist to consider other important and related diagnoses. Awareness of even biologically inert agents is important for accurate diagnosis and to avoid unnecessary and expensive diagnostic studies.

Sodium Polystyrene Sulfonate-Induced Gastric Pneumatosis: A Rare Side Effect

Kayexalate has been used in the USA since 1975 for the treatment of hyperkalemia. Prior case reports have shown that sorbitol added to kayexalate has been known to cause rare side effects of colonic necrosis. We present a unique case report of gastric pneumatosis as a complication of kayexalate.

An unusual recurrent ileocolonic injury

Potassium binders (Kayexalate® and Sorbisterit®) are commonly used to treat hyperkaliemia. They are made of sodium or calcium polystyrene sulfonate. Their use is associated with multiple adverse effects including ileocolonic (or more rarely upper digestive tract) injuries which can lead to necrosis or perforations. This side effect is mostly seen in patients with chronic kidney disease or constipation. It presents with abdominal pain, diarrhea or hematochezia. The diagnosis is made when the histo-logical analysis of samples from the erythematous or ulcerated digestive wall finds polystyrene sulfonate crystals embedded in the mucosa. This diagnosis can be suspected by taking a careful initial drug inventory, if the clinician is aware of this rare but serious adverse effect. The lack of specificity of clinical symptoms and endoscopic lesions makes this inventory even more essential. Treatment is mainly supportive and requires cessation of the drug, while surgery is inevitable in the most severe cases.

"Stranger things" in the gut: uncommon items in gastrointestinal specimens

Organic (such as parasites or vegetable remnants) and inorganic substances may be encountered during routine pathology diagnostic work up of endoscopic gastrointestinal biopsy samples and major resections, causing possible diagnostic conundrums for the young and not so young pathologists. The main aim of this review is the description of the most frequent oddities one can encounter as foreign bodies, in gastrointestinal pathology, on the basis of the current literature and personal experience. The types of encountered substances are divided into four principal categories: parasites (helminths such as Enterobius vermicularis, Strongyloides, Schistosoma, and Anisakis, and protozoa such as Entamoeba, Giardia and some intestinal coccidia); drugs and pharmaceutical fillers (found as deposits and as bystanders, innocent or not); seeds (possibly confused with worms) and plant remnants; pollutants (secondary to post-resection or post-biopsy contamination of the sample). An ample library of images is provided in order to consent easy referencing for diagnostic routine.

Lower Gastrointestinal Bleeding Associated With Sodium Polystyrene Sulfonate Use

Sodium polystyrene sulfonate (kayexalate) is a cation-exchange resin widely used in the management of hyperkalemia. Gastrointestinal adverse events are uncommon; symptoms are nonspecific, and mucosal injury can range from mild ulceration to bowel perforation. An 81-year-old man was admitted because of decompensation of cirrhosis with acute kidney injury and hyperkalemia, treated with sodium polystyrene sulfonate. During admission, he presented multiple episodes of hematochezia, accompanied by tachycardia and hemoglobin drop. Colonoscopy revealed colonic ulceration, and histopathological findings were compatible with ulceration due to kayexalate injury. Despite rare, the widespread use of sodium polystyrene sulfonate puts a large population at risk of serious complications related to its use.

Small crystals with severe consequences

We present the case of a 23-year-old patient who developed a severe gastric ischemia after the ingestion of a single dose of sodium polystyrene sulfonate (SPS) orally. Emergency surgery confirmed extensive full thickness gastric necrosis, prompting a total gastrectomy. Histopathology showed kayexalate crystals in the gastric wall, suggesting SPS-related ischemic gastritis. After radical resection of the affected stomach, this young patient was able to fully recover. Although effective, the widespread use of SPS to treat hyperpotassemia remains a debated topic because of rare but serious adverse events like the forming of kayexalate crystal residues in the gastrointestinal tract. These crystal residues are mostly found in the large intestine and can lead to ulceration and necrosis. Physicians need to be aware of this rare but potentially devastating adverse effect of SPS ingestion.

Rectal ulcer in a hemodialysis patient receiving Kayexalate®

Kayexalate can cause severe unrecognized GI lesions. Diagnosis of kayexalate crystals in GI biopsy samples is important. Pathologists and clinicians should work hand in hand. New drugs should be available to all patients to treat hyperkalemia.

Kayexalate-Induced Esophageal Ulceration in a Patient with Decompensated Cirrhosis: A Review of the Literature

Hyperkalemia is one of the most common electrolyte abnormalities encountered in clinical practice. The treatment of hyperkalemia includes removal of excess potassium from the body using cation exchange resins, e.g., sodium polystyrene sulfonate (Kayexalate) is one of the most practiced modalities in clinical medicine. Colonic mucosal necrosis and perforation are the serious gastrointestinal side effects associated with sodium polystyrene sulfonate (SPS) use, which have been reported with or without concomitant use of sorbitol. However, the catastrophic bleeding esophageal ulcer has been rarely described in our literature search. Due to the risk of colonic necrosis, the FDA has issued a warning to avoid concomitant sorbitol use with Kayexalate. We present an individual with acute hematemesis due to bleeding esophageal ulcer immediately after treatment with Kayexalate therapy. Though the exact mechanism by which Kayexalate causes esophageal ulcer to be elucidated, nonetheless it is worthwhile to be vigilant about its potential adverse effects. Our case highlights the rare but certainly the life-threatening complication of Kayexalate therapy.

Adverse Gastrointestinal Effects with Kayexalate or Kalimate: A Comprehensive Review

BACKGROUND

Patients with hyperkalemia are commonly treated with Kayexalate or Kalimate. Both drugs are associated with some fatal gastrointestinal (GI) adverse events (AEs).

AIM

To assess the clinical characteristics and outcomes of GI AEs induced by Kayexalate or Kalimate from published case reports.

METHODS

We conducted a systematic review of case reports of Kayexalate or Kalimate-induced GI AEs, from PubMed, Medline, Cochrane Library, Clinical Key, and Google Scholar databases (1948 to March 31, 2020). We analyzed the clinical characteristics, GI AEs, and risk factors of enrolled patients.

RESULTS

We identified 41 published articles describing 135 cases of GI AEs induced by Kayexalate (103 cases) or Kalimate (32 cases). The mean age of all patients was 55.5 years. Most patients were male (54.8%). As high as 55.6% preparations were administered with sorbitol whereas 44.4% preparations had no sorbitol. The average time causing GI AEs was 19.8 days. Colon was the most commonly affected site (76.3%). Drug crystals were histopathologically proven in 95.5% of the patients. Meanwhile, mortality was reported in 20.7%.

CONCLUSION

Kayexalate or Kalimate, without or with sorbitol combination, may be related to fatal GI damage. Uremia, hypertension, and transplantation are predisposing factors. Clinicians should be careful in prescribing Kayexalate or Kalimate to patients.

Esophageal necrosis associated with sodium polystyrene sulfonate (Kayexalate) use

Acute esophageal necrosis is a rare cause of gastrointestinal bleeding. Endoscopically, it appears as a circumferential black-appearing mucosa affecting almost universally the mid and distal esophagus. Risk factors include low flow states, malnutrition, alcoholism, and the presence of multiple comorbidities. Prolonged exposure to gastric secretions and direct contact with corrosive agents also induce mucosal ischemia. Sodium polystyrene sulfonate use has been associated with severe gastrointestinal adverse events, including increased risk of small bowel and colonic necrosis and perforation. In susceptible individuals, sodium polystyrene sulfonate can also induce esophageal ischemia and necrosis, as illustrated in this case.

Initiation of sodium polystyrene sulphonate and the risk of gastrointestinal adverse events in advanced chronic kidney disease: a nationwide study

BACKGROUND

Despite long-standing clinical use of sodium polystyrene sulphonate (SPS) for hyperkalaemia management in chronic kidney disease (CKD), its safety profile remains poorly investigated.

METHODS

We undertook an observational analysis of nephrology-referred adults with incident CKD Stage 4+ in Sweden during 2006-16 and with no previous SPS use. We studied patterns of use and adverse events associated to SPS initiation during follow-up. Patterns of SPS use were defined by chronicity of treatment and by prescribed dose. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) associated with SPS initiation (time-varying exposure) for the risk of severe (intestinal ischaemia, thrombosis or ulceration/perforation) and minor (de novo dispensation of laxatives or anti-diarrheal drugs) gastrointestinal (GI) events.

RESULTS

Of 19 530 SPS-naïve patients with CKD, 3690 initiated SPS during follow-up. A total of 59% took SPS chronically, with an average of three dispensations/year. The majority (85%) were prescribed lower dosages than specified on the product label. During follow-up, 202 severe and 1149 minor GI events were recorded. SPS initiation was associated with a higher incidence of severe adverse events [adjusted HR 1.25 95% CI 1.05-1.49)], particularly in those receiving per label doses [1.54 (1.09-2.17)] and mainly attributed to ulcers and perforations. SPS initiation was also associated with higher incidence of minor GI events [adjusted HR 1.11 (95% CI 1.03-1.19)], regardless of dose, and mainly accounted for by de novo dispensation of laxatives.

CONCLUSIONS

Initiation of SPS in patients with advanced CKD is associated with a higher risk of severe GI complications as well as the initiation of GI-related medications, particularly when prescribed at per label doses.

Clinical and Forensic Aspects of Pharmacobezoars

BACKGROUND

Pharmacobezoars are specific types of bezoars formed when medicines, such as tablets, suspensions, and/or drug delivery systems, aggregate and may cause death by occluding airways with tenacious material or by eluting drugs resulting in toxic or lethal blood concentrations.

OBJECTIVE

This work aims to fully review the state-of-the-art regarding pathophysiology, diagnosis, treatment, and other relevant clinical and forensic features of pharmacobezoars.

RESULTS

Patients of a wide range of ages and of both sexes present with signs and symptoms of intoxications or more commonly gastrointestinal obstructions. The exact mechanisms of pharmacobezoar formation are unknown but are likely multifactorial. The diagnosis and treatment depend on the gastrointestinal segment affected and should be personalized to the medication and the underlying factor. A good and complete history, physical examination, image tests, upper endoscopy, and surgery through laparotomy of the lower tract are useful for diagnosis and treatment.

CONCLUSION

Pharmacobezoars are rarely seen in clinical and forensic practice. They are related to controlled or immediate-release formulations, liquid, or non-digestible substances, in normal or altered digestive motility/anatomy tract, and in overdoses or therapeutic doses, and should be suspected in the presence of risk factors or patients taking drugs which may form pharmacobezoars.

Intestinal necrosis related to administration of cation exchange resin without sorbitol: A retrospective analysis of 61 patients with end-stage renal diseases

Intestinal necrosis associated with cation exchange resin (CER) is considered related to sorbitol, but it has been reported even in patients receiving CER alone. This study was performed to identify the risk factors of CER-related intestinal necrosis. The pathological database of 61 end-stage renal disease patients with surgical intervention for intestinal perforation was reviewed. The correlations between CER treatment and clinicopathological factors were studied among three groups: (i) patients administered CER and with CER at the perforation site (n = 23), (ii) patients administered CER with undetected CER at the perforation site (n = 12) and (iii) patients not administered CER (n = 26). The majority of the perforation site in group 1 was in the sigmoid colon (82.6%) with significantly higher average age and more frequent CER adhesion rates to the mucosa around the perforation site than group 2. The laxative administration rate in group 1 was significantly higher than group 3 and tended to be higher than group 2. The incidence of CER-related intestinal necrosis was estimated at 0.57%. CER should be used with extreme caution in elderly patients with passage disturbance.

Risk of Hospitalization for Serious Adverse Gastrointestinal Events Associated With Sodium Polystyrene Sulfonate Use in Patients of Advanced Age

IMPORTANCE

Sodium polystyrene sulfonate is commonly prescribed for the treatment of hyperkalemia. Case reports of intestinal injury after administration of sodium polystyrene sulfonate with sorbitol resulted in a US Food and Drug Administration warning and discontinuation of combined 70% sorbitol-sodium polystyrene sulfonate formulations. There are ongoing concerns about the gastrointestinal (GI) safety of sodium polystyrene sulfonate use.

OBJECTIVE

To assess the risk of hospitalization for adverse GI events associated with sodium polystyrene sulfonate use in patients of advanced age.

DESIGN, SETTING, AND PARTICIPANTS

Population-based, retrospective matched cohort study of eligible adults of advanced age (≥66 years) dispensed sodium polystyrene sulfonate from April 1, 2003, to September 30, 2015, in Ontario, Canada, with maximum follow-up to March 31, 2016. Initial data analysis was conducted from August 1, 2018, to October 3, 2018; revision analysis was conducted from February 25, 2019, to April 2, 2019. Cox proportional hazards regression models were used to examine the association of sodium polystyrene sulfonate use with a composite of GI adverse events compared with nonuse that was matched via a high-dimensional propensity score. Additional analyses were limited to a subpopulation with baseline laboratory values of estimated glomerular filtration rate and serum potassium level.

EXPOSURE

Dispensed sodium polystyrene sulfonate in an outpatient setting.

MAIN OUTCOMES AND MEASURES

The primary outcome was a composite of adverse GI events (hospitalization or emergency department visit with intestinal ischemia/thrombosis, GI ulceration/perforation, or resection/ostomy) within 30 days of initial sodium polystyrene sulfonate prescription.

RESULTS

From a total of 1 853 866 eligible adults, 27 704 individuals were dispensed sodium polystyrene sulfonate (mean [SD] age, 78.5 [7.7] years; 54.7% male), and 20 020 sodium polystyrene sulfonate users were matched to 20 020 nonusers. Sodium polystyrene sulfonate use compared with nonuse was associated with a higher risk of an adverse GI event over the following 30 days (37 events [0.2%]; incidence rate, 22.97 per 1000 person-years vs 18 events [0.1%]; incidence rate, 11.01 per 1000 person-years) (hazard ratio, 1.94; 95% CI, 1.10-3.41). Results were consistent in additional analyses, including the subpopulation with baseline laboratory values (hazard ratio, 2.91; 95% CI, 1.38-6.12), and intestinal ischemia/thrombosis was the most common type of GI injury.

CONCLUSIONS AND RELEVANCE

The use of sodium polystyrene sulfonate is associated with a higher risk of hospitalization for serious adverse GI events. These findings require confirmation and suggest caution with the ongoing use of sodium polystyrene sulfonate.

Fractal Deposits of a Hemostatic Hydrophilic Polymer in Mohs Micrographic Surgery Frozen Sections: A Histologic Analysis and Comparison With Sodium Polystyrene Sulfonate (Kayexalate)

Hydrophilic polymer with potassium ferrate (HPPF) powder is available as an over-the-counter hemostatic agent used by patients to stop superficial bleeding. In dermatology, it is applied to stop bleeding after superficial shave or punch biopsies or in open wounds after Mohs micrographic surgery. Despite its widespread availability, however, HPPF in histopathologic skin sections is highly unusual. We noted HPPF in skin closely resembles sodium polystyrene sulfonate (SPS) seen in colonic necrosis; SPS is a potassium binder given orally or rectally in hyperkalemic patients with end-stage renal disease. We describe the in vivo and in vitro histologic appearance of HPPF, compare HPPF with SPS, and discuss its potential migration into blood or lymph vessels.

Review of Drug-induced Injury in Mucosal Biopsies From the Tubular Gastrointestinal Tract

The use of prescription and over-the-counter medications is on the rise in the US population, especially among those aged 65 and over, with over 46% of the population taking at least 1 prescription medication. Given the frequency of medication use, and that the majority of these medications are taken orally, it has become increasingly relevant for pathologist examining endoscopically obtained gastrointestinal tract mucosal biopsies to consider and recognize patterns of mucosal injury associated with various drugs. Reports on injuries associated with certain classes of drugs can be scattered among different sources, making a comprehensive view of various injury patterns and the drugs known to cause them difficult to obtain. Herein, we provide a comprehensive overview of the drugs known to cause mucosal injuries in the tubular gastrointestinal tract organized by the organ involved and the prominent pattern of injury.

New treatments for hyperkalaemia: clinical use in cardiology

Hyperkalaemia causes significant burden, and even mild hyperkalaemia has been independently associated with increased morbidity and mortality. Patients with chronic disease states, such as heart failure, hypertension, chronic kidney disease and diabetes mellitus, are increasingly susceptible to the development of hyperkalaemia. Options for management of hyperkalaemia had mainly been limited to short-term, temporizing methods with focus on rapid achievement of normokalaemia. Until recently, there was a lack of safe, efficacious and well-tolerated therapies for long-term management. Two novel potassium binders, patiromer and sodium zirconium cyclosilicate, have recently been approved by the US Food and Drug Administration for the management of hyperkalaemia. This review discusses these potassium binders with focus largely on the clinical implications of these agents in patients with chronic cardiovascular conditions.

Review article: the pharmacological causes of colon ischaemia

BACKGROUND

Colon ischaemia is the most common ischaemic disorder of the gastrointestinal system, can affect any segment of the colon, and may present with a range of symptoms. Diagnosis can be challenging due to symptom overlap with other conditions, varied aetiology, and often rapid and self-resolving course.

AIM

To review comprehensively the literature regarding the pharmacological aetiologies of colonic ischaemia to enhance the understanding of the various mechanisms of disease, presentations, distribution, and outcomes.

METHODS

A PubMed search for "colon ischaemia" and "ischaemic colitis" alone as well as in combination with various known pharmacologic causes was performed. Only the highest quality and relevant literature was included in this review. The quality of the literature for each association was rated by the authors and a consensus was made when discrepancies were encountered. Only associations that were deemed "moderate" or "strong" were included.

RESULTS

The literature considering pharmacologically associated colonic ischaemia is diverse, lacks codification and is characterised by numerous case reports and case series. Constipation-inducing drugs, digoxin, hormonal therapies, illicit drugs, immunomodulators, laxatives, and NSAIDs were strongly associated with colonic ischaemia. Antimicrobials, appetite suppressants, chemotherapies, decongestants, diuretics, ergot alkaloids, serotonin agents, statins, and vasopressor agents were moderately associated.

CONCLUSIONS

Patients presenting with abdominal pain, diarrhoea, or bloody stool need to be evaluated for the possibility of this condition and treated accordingly. Timely diagnosis is necessary to improve patient outcomes. This review aims to increase awareness among clinicians regarding the presentation of pharmacologically induced colonic ischaemia.

The Successful Treatment of Sodium Polystyrene Sulfonate-induced Enteritis Diagnosed by Small Bowel Endoscopy

Sodium polystyrene sulfonate (SPS: Kayexalate^®) is an ion-exchange resin used to treat hyperkalemia in patients with chronic kidney disease. It is known that this resin sometimes causes colonic necrosis and perforation, but there are few reports about small bowel necrosis associated with SPS. We herein report the case of a patient who developed SPS-induced small bowel necrosis, which was diagnosed based on the examination of a small bowel endoscopic biopsy specimen. The SPS-induced small bowel necrosis was resistant to conservative treatment including the cessation of SPS, and finally required surgical bowel resection.

Unique causes of esophageal inflammation: a histopathologic perspective

Gastroenterologists frequently perform endoscopic esophageal mucosal biopsies for pathologic diagnosis in patients experiencing symptoms of esophagitis. The more common causes of esophagitis diagnosed on esophageal mucosal biopsy include reflux esophagitis, eosinophilic esophagitis, and infectious esophagitis caused by Candida albicans, herpes simplex virus, and/or cytomegalovirus. However, there are several causes of esophagitis seen less frequently by pathologists that are very important to recognize. We discuss unique types of esophageal inflammation, including acute bacterial esophagitis, esophageal manifestations of dermatologic diseases, medication-induced esophageal injury, and sloughing esophagitis; and we review their clinical and histopathologic features.

Hyperkalemia in the Hypertensive Patient

PURPOSE OF REVIEW

Hyperkalemia develops in a patient with systemic arterial hypertension (HTN) if one or more risk factors are present, namely chronic kidney disease (CKD) (especially severe stage 4-5 CKD), diabetes mellitus (DM), heart failure (HF), or pharmacological therapies that interfere with potassium homeostasis, mainly through renin-angiotensin-aldosterone inhibition (RAASi). Hyperkalemia is a considerable reason of morbidity (emergency department (ED) visits and hospitalizations) and portends a higher mortality risk in patients at risk; for instance, hyperkalemia increases the risk of mortality within 1 day of a hyperkalemic event. This review aims to identify the risk factors for high-serum potassium, highlight the risk versus benefit of RAASi in certain patient populations, and outline preventive as well as therapeutic strategies for hyperkalemia.

RECENT FINDINGS

A growing body of evidence supports the safety and efficacy of cation-exchange resins, patiromer, or sodium zirconium cyclosilicate, in patients with a compelling indication for RAASi, yet in whom such therapy was complicated by hyperkalemia, allowing these patients to benefit from continued RAASi therapy. In summary, novel cation exchange polymers present the clinician with a new and safe strategy to address hyperkalemia in patients with a compelling indication for ongoing RAASi therapy instead of withdrawal of such therapy.

Treatment of Hyperkalemia in Heart Failure

PURPOSE OF REVIEW

The aim of this paper is to discuss strategies for prevention and management of hyperkalemia in patients with heart failure, including the role of novel therapies.

RECENT FINDINGS

Renin-angiotensin-aldosterone system (RAAS) antagonists, including angiotensin-converting enzyme inhibitors (ACEI), angiotensin receptor blockers (ARB), and mineralocorticoid receptor antagonists (MRA) decrease mortality and morbidity in heart failure but increase the risk of hyperkalemia, especially when used in combination. Prevention of hyperkalemia and its associated complications requires careful patient selection, counseling regarding dietary potassium intake, awareness of drug interactions, and regular laboratory surveillance. Recent data suggests that the risk of hyperkalemia may be further moderated through the use of combined angiotensin-neprilysin inhibitors, novel MRAs, and novel potassium binding agents. Clinicians should be mindful of the risk of hyperkalemia when prescribing RAAS inhibitors to patients with heart failure. In patients at highest risk, such as those with diabetes, the elderly, and advanced chronic kidney disease, more intensive laboratory surveillance of potassium and creatinine may be required. Novel therapies hold promise for reducing the risk of hyperkalemia and enhancing the tolerability of RAAS antagonists.

Other Forms of Esophagitis: It Is Not Gastroesophageal Reflux Disease, So Now What Do I Do?

Esophagitis results from diverse causes, including gastroesophageal reflux, immune-mediated or allergic reactions, therapeutic complications, and infections. The appropriate clinical management differs in each of these situations and is often guided by pathologic interpretation of endoscopic mucosal biopsy specimens. This review summarizes the diagnostic features of unusual forms of esophagitis, including eosinophilic esophagitis, lymphocytic esophagitis, esophagitis dissecans superficialis, drug-induced esophageal injury, and bullous disorders. Differential diagnoses and distinguishing features are emphasized.

The Many Faces of Medication-Related Injury in the Gastrointestinal Tract

Every year many new medications are approved for clinical use, several of which can cause clinically significant gastrointestinal tract toxicity. This article emphasizes the histologic features and differential diagnosis of drug-induced injury to the gastrointestinal mucosa. Ultimately, clinical correlation and cessation of a drug with resolution of symptoms are needed to definitively confirm a drug as a causative factor in mucosal injury. Recognizing histologic features in gastrointestinal biopsies, however, can allow surgical pathologists to play a key role in establishing a diagnosis of drug-induced gastrointestinal toxicity.

Treatment of Severe Hyperkalemia: Confronting 4 Fallacies

Severe hyperkalemia is a medical emergency that can cause lethal arrhythmias. Successful management requires monitoring of the electrocardiogram and serum potassium concentrations, the prompt institution of therapies that work both synergistically and sequentially, and timely repeat dosing as necessary. It is of concern then that, based on questions about effectiveness and safety, many physicians no longer use 3 key modalities in the treatment of severe hyperkalemia: sodium bicarbonate, sodium polystyrene sulfonate (Kayexalate [Concordia Pharmaceuticals Inc., Oakville, ON, Canada], SPS [CMP Pharma, Farmville, NC]), and hemodialysis with low potassium dialysate. After reviewing older reports and newer information, I believe that these exclusions are ill advised. In this article, I briefly discuss the treatment of severe hyperkalemia and detail why these modalities are safe and effective and merit inclusion in the treatment of severe hyperkalemia.

Patterns of Gastric Injury: Beyond Helicobacter Pylori

Gastric biopsies are routinely obtained from patients with symptoms related to the gastrointestinal tract and, as a result, a variety of histologic changes are observed in patients with or without endoscopic evidence of mucosal injury. Although Helicobacter pylori-related gastritis is still common, several other patterns of mucosal injury are increasingly encountered. These patterns of injury are classified based on the nature and distribution of inflammation, location of epithelial cell injury, presence of crystal or pigment deposition, and/or other unique features. This article discusses each of these patterns and provides a differential diagnosis for each.

OsmoPrep-associated Gastritis: A Histopathologic Mimic of Iron Pill Gastritis and Mucosal Calcinosis

We have identified 8 cases of gastritis characterized by the presence of purple to black granular deposits in the superficial mucosa associated with marked reactive epithelial changes. In each case, the patient had taken OsmoPrep, a tablet form of sodium phosphate used for bowel preparation just before upper endoscopy and had undergone concurrent colonoscopy. Endoscopic findings ranged from normal gastric mucosa to severe inflammation, congestion, and friability. No other gastrointestinal sites were noted to contain the deposits or show similar mucosal injury. On initial histologic review, the deposits raised the differential diagnosis of elemental iron and mucosal calcinosis. However, none of the patients was noted to be taking iron supplements, and none had a history of renal disease or other cause of calcium dysmetabolism. Histochemical stains revealed the deposits were negative on Perls' iron stain (8/8 cases), positive on von Kossa stain (7/8 cases), and negative on Alizarin Red stain (8/8 cases)-a histochemical profile compatible with sodium phosphate but inconsistent with mucosal calcium. A crushed OsmoPrep tablet was subjected to processing and demonstrated similar histologic features and histochemical profile. In addition, biopsies of 20 consecutive patients who did not take OsmoPrep and who underwent concurrent endoscopy and colonoscopy were reviewed, and no deposits with similar histochemical profile were identified. In summary, we have characterized a unique form of gastritis associated with OsmoPrep use. Attention to clinical history and use of a select panel of histochemical stains allow for accurate diagnosis.

Expert Panel Recommendations for the Identification and Management of Hyperkalemia and Role of Patiromer in Patients with Chronic Kidney Disease and Heart Failure

Virtual panel meetings were conducted among 7 physicians, all of whom are independent experts, including 3 nephrologists, 2 cardiologists, and 2 emergency medicine physicians (the panel). The panel met with the purpose of discussing the current treatment landscape, treatment challenges, economic impact, and gaps in care for patients with hyperkalemia that is associated with heart failure and chronic kidney disease. The stated goal of the panel discussion was to develop practical solutions in the identification and management of hyperkalemia in this patient population. The panel noted that hyperkalemia is a serious condition that can lead to life-threatening complications, yet the treatment paradigm for hyperkalemia has remained without major advances for approximately 50 years, until the approval of patiromer. A number of issues still exist in the management of this patient population, including the lack of uniform treatment guidelines and consensus regarding the approach to treatment. As part of its effort, the panel developed an algorithm, the Proposed Diagnostic Algorithm for Hyperkalemia Treatment in the Acute Care Setting/Chronic Care. The panel agreed that patiromer appears to be a viable option for the management of hyperkalemia in patients with chronic kidney disease and/or heart failure and in patients who experience chronic hyperkalemia.

DISCLOSURES

This panel discussion was funded by Relypsa and facilitated by Magellan Rx Management. Rafique is a principal investigator for Relypsa and serves as a consultant for Instrumentation Laboratory, Magellan Health, Relypsa, and ZS-Pharma. Butler serves as consultant for Amgen, AstraZeneca, Bayer, Boehringer Ingelheim, CardioCell, Janssen, Merck, Novartis, Relypsa, and ZS-Pharma. Lopes and Farnum are employed by Magellan Rx Management. Rafique designed the management protocol for this panel discussion and contributed to the writing and editing of this report document. The other authors report no conflicting interests. Relypsa is the manufacturer of Veltassa (patiromer).

Efficacy and Safety of Patiromer in Hyperkalemia: A Systematic Review and Meta-Analysis

BACKGROUND

Patients at the highest risk of hyperkalemia are those with chronic kidney disease (CKD) stages 3 and 4.

OBJECTIVE

To evaluate the efficacy and safety of patiromer in hyperkalemia in patients with heart failure or CKD.

METHODS

The Cochrane Renal Group's Specialized Register was searched through contact with the Trials' Search Coordinator. We aimed at including randomized controlled trials with patiromer in patients with developed or risks of developing hyperkalemia, comparing against an active comparator or placebo. Three studies matched our inclusion and exclusion criteria, which we included in the meta-analysis. All-cause mortality, reduction in hospitalization, episodes of hypokalemia or hyperkalemia, and cardiovascular and gastrointestinal adverse events during the treatment period were our primary outcomes. Serial change in serum potassium (K⁺) until end of treatment or follow-up during the trial period and all other reported adverse reactions during the treatment period were our secondary outcomes. Meta-analysis (RevMan version 5.3.5) and descriptive statistics were used.

RESULTS

There was a non-significant improvement in all-cause mortality and serious cardiovascular events with patiromer than placebo. Hospitalization data were unavailable. Although serious gastrointestinal events were more common with placebo, there was a significant reduction ( P = .02) in the risk of non-serious gastrointestinal events with placebo. Patiromer lowered serum K⁺ more than placebo, and there were more patients developing hyperkalemia with placebo. High-dose patiromer was associated with better efficacy in some parameters but with more adverse events.

CONCLUSION

Although patiromer seems promising, more trials with active comparator are essential to finalize its indication and use in hyperkalemia.

Challenges in Diagnosing Medication Resins in Surgical Pathology Specimens: A Crystal-Clear Review Guide

CONTEXT

- Medication resins, including Kayexalate, sevelamer, and bile acid sequestrants, can be encountered in gastrointestinal tract specimens. Their classic histologic appearances have been well documented, but pathologist recognition of the resins is 75%, patient history is not always available, and atypical morphologic findings are sometimes present.

OBJECTIVE

- To offer a succinct overview of resins in the gastrointestinal tract, including typical and atypical appearances, in order to serve as a quick reference guide.

DATA SOURCES

- The study comprises published literature, survey data, and our personal experiences.

CONCLUSIONS

- Classic morphology is the benchmark for identifying these resins, but color, location, and fish scale pattern can deviate from the norm, making proper identification a challenge. Patient history should be sought whenever possible, and ancillary staining is an option when necessary. Additionally, the presence of resins should prompt the pathologist to search for potentially related diagnoses (namely, causes of diarrhea in patients on bile acid sequestrants and diagnoses associated with renal failure in patients on Kayexalate or sevelamer).

The Impact of New Technologic and Molecular Advances in the Daily Practice of Gastrointestinal and Hepatobiliary Pathology

The practice of anatomic pathology, and of gastrointestinal pathology in particular, has been dramatically transformed in the past decade. In addition to the multitude of diseases, syndromes, and clinical entities encountered in daily clinical practice, the increasing integration of new technologic and molecular advances into the field of gastroenterology is occurring at a fast pace. Application of these advances has challenged pathologists to correlate newer methodologies with existing morphologic criteria, which in many instances still provide the gold standard for diagnosis. This review describes the impact of new technologic and molecular advances on the daily practice of gastrointestinal and hepatobiliary pathology. We discuss new drugs that can affect the gastrointestinal tract and liver, new endoluminal techniques, new molecular tests that are often performed reflexively, new imaging techniques for evaluating hepatocellular carcinoma, and modified approaches to the gross and histologic assessment of tissues that have been exposed to neoadjuvant therapies.

Medication-associated gastrointestinal tract injury

Medication-associated gastrointestinal (GI) tract injury has been known for centuries for some medications. The more recently introduced biologicals are a class of drugs that constantly increases, and as such, the spectrum of GI tract side effects is steadily growing. This review covers not only long-known GI tract side effects of drugs but also those more recently described. A comprehensive but concise list of medications used in daily practice and associated with GI tract injury is presented.

Substituted Polyesters by Thiol-Ene Modification: Rapid Diversification for Therapeutic Protein Stabilization

Many proteins, especially those used as therapeutics, are unstable to storage and shipping temperatures, leading to increased costs in research and industry. Therefore, the design and synthesis of novel stabilizers is an important area of investigation. Herein we report new degradable polymers that stabilize proteins to environmental stressors such as refrigeration and elevated temperature. Specifically, polycaprolactones with different pendant groups were synthesized and surveyed for their ability to stabilize an important therapeutic protein to storage and shipping conditions. Ring-opening polymerization (ROP) of an allyl-substituted caprolactone monomer was carried out using the organocatalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) to yield a well-defined, alkene-substituted degradable polymer, which was used as a common backbone to control for the degree of polymerization. Relevant side chains such as trehalose, lactose, glucose, carboxybetaine, and oligo(ethylene glycol) were installed via postpolymerization thiol-ene reactions. These degradable polymers were then employed as excipients for the stabilization of the therapeutic protein granulocyte colony-stimulating factor (G-CSF) against storage at 4 °C and shipping temperatures of 60 °C. The best stabilization was observed using the trehalose- and zwitterion- substituted polyesters. Both the trehalose- and carboxybetaine-substituted pCL were further investigated with regard to molecular weight dependence, and it was found that the molecular weight was minimally important for stabilization to refrigeration, but critical for G-CSF stabilization at elevated temperatures. Both high performing zwitterionic and trehalose polyesters were also degraded, and the polymers and degradation products were shown to be noncytotoxic. This work provides potential biocompatible polymers for stabilization of the important therapeutic G-CSF, as well as a general platform for the future discovery of new polymeric protein stabilizers.