Sevelamer-Induced Gastrointestinal Injury Presenting as Gastroenteritis

Sevelamer-Induced Gastrointestinal Disease in 12 Patients with End-Stage Renal Disease: A Case Series

INTRODUCTION

Isolated case reports and case series have linked the use of sevelamer to severe gastrointestinal (GI) inflammation and perforation among patients with end-stage renal disease.

METHODS

In this study, we identified 12 cases of biopsy-proven sevelamer-induced gastrointestinal disease from a large urban community hospital over the course of 5 years. We described baseline characteristics, sites and types of injury, histological findings, timing and dosing of sevelamer initiation compared with symptom onset, and in a smaller subset, endoscopic resolution post drug cessation. We also reviewed preexisting conditions to identify trends in populations at risk.

RESULTS

Several of the patients reviewed had preexisting conditions of decreased motility and/or impaired mucosal integrity. The presentation of disease was broad and included both upper-GI and lower-GI pathologies and in varying severity.

DISCUSSION

There is a broad phenotypic range of sevelamer-induced gastrointestinal disease. As this becomes a more frequently recognized pathology, clinicians should be aware of how it may present and which populations may be more susceptible.

[Colonic Mass Secondary to Sevelamer-associated Rectal Ulcer]

The phosphorous balance is clinically important in increasing the long-term outcomes and preventing complications of end-stage renal disease. Sevelamer is a phosphate binder used widely to regulate hyperphosphatemia. On the other hand, gastrointestinal side effects increase with increasing sevelamer intake. A 29-year-old male with end-stage renal disease of IgA nephropathy on maintenance hemodialysis was admitted for diffuse alveolar bleeding and pneumonia. He presented with a low-grade fever and watery diarrhea tinged with blood. Initially, a Clostridioides difficile-associated diarrhea treatment was started with positive findings of Clostridioides difficile toxin and culture. Despite this, there was no improvement in the symptoms even with the appropriate antibiotic treatment. Computed tomography of the abdomen and pelvis revealed an occlusive mass in the rectum and secondary obstructive changes in the sigmoid colon. The initial suspicion was a malignancy or fungal infection. Sigmoidoscopy with a biopsy identified the mass as a lump of mucous material with the entire lumen covered with exudate. The subsequent histopathology examination revealed a colonic mucosal injury and characteristic "fish scale"-like sevelamer crystals in the exudate. The diagnosis of a sevelamer-induced rectal ulcer was made. We report this case of a sevelamer-associated rectal ulcer of the sigmoid.

Sevelamer Carbonate Crystal-Induced Colitis

Hyperphosphatemia is a common and well-described complication of end-stage renal disease. Despite strict dietary constraints and compliance, phosphate binders such as calcium acetate and/or sevelamer carbonate are also needed to treat secondary hyperparathyroidism. This case vignette describes an underrecognized adverse effect of a phosphate binder, sevelamer carbonate, inducing colitis in a 47-year-old male with insulin-dependent diabetes complicated by end-stage renal disease. He presented for recurrent abdominal pain with associated nausea and was found to have multiple circumferential lesions on computed tomography including distal ascending, transverse, and proximal descending colon. Colonoscopy demonstrated nearly obstructing lesions worrisome for colonic ischemia or inflammatory bowel disease. Pathological review of histology demonstrated ragged colonic mucosa with ulcerative debris and nonpolarizing crystalline material at the sites of ulceration, morphologically consistent with the phosphate binder, sevelamer carbonate. Sevelamer carbonate was discontinued, and the patient was transitioned to calcium carbonate with strict dietary restrictions. His symptoms improved with the cessation of sevelamer, and he was subsequently discharged home. He eventually underwent renal transplant without redevelopment of symptoms. Recognition of this underreported complication of sevelamer carbonate, phosphate binder, is of utmost importance in directing appropriate therapy with cessation of this medication in the setting of gastrointestinal complaints or more specifically enteritis and colitis. Clinicians providing care to end-stage renal patients taking either sevelamer and/or sodium polystyrene sulfonate should have increased awareness of the possible gastrointestinal side effects.

Sevelamer Use in End-Stage Kidney Disease (ESKD) Patients Associates with Poor Vitamin K Status and High Levels of Gut-Derived Uremic Toxins: A Drug-Bug Interaction?

Gut microbial metabolism is not only an important source of uremic toxins but may also help to maintain the vitamin K stores of the host. We hypothesized that sevelamer therapy, a commonly used phosphate binder in patients with end-stage kidney disease (ESKD), associates with a disturbed gut microbial metabolism. Important representatives of gut-derived uremic toxins, including indoxyl sulfate (IndS), p-Cresyl sulfate (pCS), trimethylamine N-oxide (TMAO), phenylacetylglutamine (PAG) and non-phosphorylated, uncarboxylated matrix-Gla protein (dp-ucMGP; a marker of vitamin K status), were analyzed in blood samples from 423 patients (65% males, median age 54 years) with ESKD. Demographics and laboratory data were extracted from electronic files. Sevelamer users (n = 172, 41%) were characterized by higher phosphate, IndS, TMAO, PAG and dp-ucMGP levels compared to non-users. Sevelamer was significantly associated with increased IndS, PAG and dp-ucMGP levels, independent of age, sex, calcium-containing phosphate binder, cohort, phosphate, creatinine and dialysis vintage. High dp-ucMGP levels, reflecting vitamin K deficiency, were independently and positively associated with PAG and TMAO levels. Sevelamer therapy associates with an unfavorable gut microbial metabolism pattern. Although the observational design precludes causal inference, present findings implicate a disturbed microbial metabolism and vitamin K deficiency as potential trade-offs of sevelamer therapy.

Lanthanum phosphate binder-induced iron deficiency anaemia

Lanthanum carbonate is a phosphate binder that is used to reduce serum phosphate levels in patients with end-stage renal disease (ESRD). Lanthanum forms insoluble lanthanum phosphate complexes that are supposed to pass through the gastrointestinal (GI) tract unabsorbed. Phosphate binders have been reported to deposit in the GI tract and can cause mucosal injury. There are few case reports of GI bleeding associated with phosphate binder deposits. This case report presents a patient with iron deficiency anaemia secondary to biopsy-proven lanthanum deposits in the upper GI tract. There were no overt signs of active GI bleeding. Patient's anaemia improved with discontinuation of the phosphate binder. Lanthanum could be a hidden cause of resistant anaemia among patients with ESRD through asymptomatic GI blood loss.

Sevelamer-Associated Rectosigmoid Ulcers in an End-Stage Renal Disease Patient

Sevelamer carbonate is a commonly prescribed anion-exchange resin administered orally to prevent hyperphosphatemia in patients with chronic kidney disease. We present a rare case of a 33-year-old man with end-stage renal disease and diabetic gastroparesis on sevelamer carbonate, who presented with hematochezia and was found to have rectosigmoid ulcers induced by sevelamer crystals. His hematochezia resolved after switching from sevelamer carbonate to lanthanum carbonate. Clinicians and pathologists must be aware of the possibility of drug-induced mucosal ulceration associated with sevelamer use as a potential etiology of a gastrointestinal bleed.