Sevelamer, a nonabsorbable dietary phosphate binder, is essential for patients with renal impairment since hyperphosphatemia is associated with an increase in all-cause mortality. Sevelamer is generally well tolerated; however, it is rarely been documented to cause gastrointestinal mucosal injury by forming sevelamer crystals and depositing within the gastrointestinal walls. We present a 35-year-old man with end-stage renal disease on peritoneal dialysis who developed abdominal pain and hematochezia. Initial imaging and endoscopic examination were concerning for ischemic enteritis, and histopathology revealed crystalloid structures surrounded by necrosis consistent with sevelamer-induced ischemic enteritis.

This systematic review was performed to understand better the myriad presentations, various therapeutic options, response to therapy, and its clinical outcomes in hyperphosphatemic tumoral calcinosis (HTC). Full texts were selected according to strict inclusion criteria. All case reports of HTC wherein baseline phosphate was measured, treatment offered was mentioned, and information on follow-up and response to therapy that were available were included. A total of 43 of 188 eligible studies (N = 63 patients) met the inclusion criteria. A list of desired data was extracted and graded for methodological quality. A total of 63 individuals (Males = 33) were included from the 43 eligible case studies. The median age of the patients was 18 (IQR 8-32) years. The most frequently involved sites were the hip/gluteal region (34/63; 53.9%) followed by the elbow/forearm (26/63; 41.2%), and the shoulder (18/63; 28.5%). Three patients had conjunctival calcific deposits. The mean (SD) phosphate was 6.9 (1.1) mg/dL. Among the subjects, 36/63 (57.1%) underwent surgical excision with some form of medical therapy. Two patients underwent only surgical excision (2.1%). One patient was maintained on follow-up (1.6%) and 24/63 (38.1%) patients were treated with medical measures. The median (IQR) follow-up duration was 3 (1-9) years. Regression or reduction in lesion size was reported in 19/63 (30.2%) subjects; 20/63 (31.7%) showed progression, 24/63 (38.1%) had features of stable disease, and mortality was reported in 3 patients (4.7%). We report for the first time a detailed description of the clinical and therapeutic response of HTC. A combination of medical measures aimed at lowering serum phosphate appears to be the cornerstone of treatment, although clinical responses may vary.

BACKGROUND: Case reports have suggested a causative role between sevelamer use and subsequent gastrointestinal bleeding (GIB), but no large observational studies have evaluated this association.
METHODS: Using the United States Renal Data System database from 2015 to 2019, we examined the association between initiation of sevelamer (vs. non-sevelamer containing phosphate binders) and GIB hospitalization as well as all-cause mortality among individuals on hemodialysis. We emulated a target trial using Cox regression models and inverse probability of treatment weights to estimate the adjusted hazard ratios (HR) across outcomes and subgroups.
RESULTS: Among 21,354 new users of phosphate binders (11,276 sevelamer and 10,078 non-sevelamer) with baseline lab data (calcium, phosphorus, hemoglobin, and albumin), there were 2,811 GIB hospitalizations and 5,920 deaths after a median follow-up of 1.3 years. Compared with the initiation of non-sevelamer binders, sevelamer was not associated with an increased risk of GIB hospitalization (89 vs. 90 events per 1,000 person-years; IPTW-HR: 0.98, 95% CI: 0.91-1.06) or all-cause mortality (220 vs. 224 events per 1,000 person-years; IPTW-HR: 0.98, 95% CI: 0.93-1.03). Subgroup analyses (such as diabetes and anti-coagulation use) were generally consistent, and there was no association between sevelamer dose and GIB hospitalization.
CONCLUSIONS: Among patients requiring hemodialysis, sevelamer (vs. non-sevelamer) containing phosphate binders was not associated with increased risk of GIB hospitalization.

Liver fibrosis is a chronic liver disease characterized by a progressive wound healing response caused by chronic liver injury. Currently, there are no approved clinical treatments for liver fibrosis. Sevelamer is used clinically to treat hyperphosphatemia and has shown potential therapeutic effects on liver diseases. However, there have been few studies evaluating the therapeutic effects of sevelamer on liver fibrosis, and the specific mechanisms are still unclear. In this study, we investigated the antifibrotic effects of sevelamer-induced low inorganic phosphate (Pi) stress in vitro and in vivo and analyzed the detailed mechanisms. We found that low Pi stress could inhibit the proliferation of activated hepatic stellate cells (HSCs) by promoting apoptosis, effectively suppressing the migration and epithelial-mesenchymal transition (EMT) of hepatic stellate cells. Additionally, low Pi stress significantly increased the antioxidant stress response. It is worth noting that low Pi stress indirectly inhibited the activation and migration of HSCs by suppressing transforming growth factor β (TGF-β) expression in macrophages. In a rat model of liver fibrosis, oral administration of sevelamer significantly decreased blood phosphorus levels, improved liver function, reduced liver inflammation, and increased the antioxidant stress response in the liver. Our study revealed that the key mechanism by which sevelamer inhibited liver fibrosis involved binding to gastrointestinal phosphate, resulting in a decrease in blood phosphorus levels, the downregulation of TGF-β expression in macrophages, and the inhibition of HSC migration and fibrosis-related protein expression. Therefore, our results suggest that sevelamer-induced low Pi stress can attenuate hepatic stellate cell activation and inhibit the progression of liver fibrosis, making it a potential option for the treatment of liver fibrosis and other refractory chronic liver diseases.

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.
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.
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.
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.

Hyperphosphatemic familial tumoral calcinosis (HFTC) presents with varied neurological manifestations that have been reported in the literature like facial palsy, vision and hearing impairment, stroke, and headache. In this article, we reported a 12-year-old girl child patient with recurrent facial weakness with bilateral hearing impairment and multiple ulcerative lesions on lower limbs and elbows. On examination, she had lower motor neuron (LMN) facial palsy with conductive hearing loss. The investigations showed hyperphosphatemia (9.3 mg/dL) with normal serum calcium (10.4 mg/dL), alkaline phosphatase (147.9 U/L), parathyroid hormone (23.12 pg/mL), and renal function tests. Elevated serum calcium and phosphorus product (96.72 mg 2 /mL 2 ) and elevated renal tubular reabsorption of phosphate (TMPxGFR) value (9.16) were noted. Skeletal survey showed hyperostosis in the long bone diaphysis, vertebrae, ribs, pelvic bone, skull, and facial bones with narrowing of cranial ostium, characteristically without any peri-articular soft tissue calcifications. An angiogram showed multiple intravascular calcifications. She was managed with a low-phosphate diet, sevelamer, niacinamide, acetazolamide, sucroferric oxyhydroxide to lower serum phosphate level, and topical sodium thiosulfate ectopic cutaneous calcification. Exome sequencing showed novel homozygous inframe deletion of ACG in FGF23 gene exon 3 at c.374_376 delins position (p. Asp125del) in the proband and a mutation in the heterozygous state in the mother and elder sibling, thus confirming a molecular diagnosis of HFTC. Our case had a unique neurological presentation of recurrent bilateral lower motor nerve facial palsy, hearing loss, multiple ectopic cutaneous calcifications without peri-articular deposits, multiple intravascular, intracranial, and vertebral endplate calcification, which has not been reported earlier. The proband showed a novel pathogenic variant suggesting an expanding phenotype of HFTC.

OBJECTIVE: Bile acid sequestrants are cholesterol-lowering drugs, which also improve glycaemic control in people with type 2 diabetes. The mechanism behind the glucose-lowering effect is unknown but has been proposed to be mediated by increased glucagon-like peptide-1 (GLP-1) secretion. Here, we investigated the glucose-lowering effects of sevelamer including any contribution from GLP-1 in people with type 2 diabetes.
METHODS: In a randomized, double-blind, placebo-controlled, crossover study, 15 people with type 2 diabetes on metformin monotherapy underwent two 17-day treatment periods with the bile acid sequestrant sevelamer and placebo, respectively, in a randomized order and with an interposed wash-out period of minimum 6 weeks. On days 15 and 17 of each treatment period, participants underwent experimental days with 4-h liquid meal tests and application of concomitant infusion of exendin(9-39)NH2 or saline.
RESULTS: Compared with placebo, sevelamer improved insulin sensitivity (assessed by homeostatic model assessment of insulin resistance) and beta-cell sensitivity to glucose and lowered fasting and postprandial plasma glucose concentrations. In both treatment periods, exendin(9-39)NH2 increased postprandial glucose excursions compared with saline but without absolute or relative difference between the two treatment periods. In contrast, exendin(9-39)NH2 abolished the sevelamer-induced improvement in beta-cell glucose sensitivity.
CONCLUSIONS: The bile acid sequestrant sevelamer improved insulin sensitivity and beta-cell sensitivity to glucose, but using the GLP-1 receptor antagonist exendin(9-39)NH2 we were not able to detect a GLP-1-mediated glucose-lowering effect of sevelamer in individuals with type 2 diabetes. Nevertheless, the sevelamer-induced improvement of beta-cell sensitivity to glucose was shown to be GLP-1-dependent.

Rationale and objective: Data suggest that non-calcium-based binders, and specifically sevelamer, may lead to lower rates of death when compared with calcium-based binders in end-stage renal disease (ESRD) patients. However, the association between sevelamer use and mortality for those with non-dialysis-dependent chronic kidney disease (NDD-CKD) patients has been uncertain. Study design: Our research is presented in a prospective cohort study. Setting and participants: A total of 966 participants with NDD-CKD stages 4-5 were enrolled in the PECERA study from 12 centers in Spain. Exposure: The participants were treated with sevelamer. Outcome: This study yielded all-cause and cardiovascular mortality outcomes. Analytical approach: We conducted an association analysis between mortality and sevelamer use with time-dependent Cox proportional hazards models. Results: After a median follow-up of 29 months (IQR: 13-36 months), death occurred in 181 participants (19%), with cardiovascular (n = 95, 53%) being the leading cause of death. In a multivariable model, the adjusted hazard ratios (HRs) for patients under sevelamer treatment were 0.44 (95% CI, 0.22 to 0.88) and 0.37 (95% CI, 0.18 to 0.75) for all-cause and cardiovascular mortality, respectively, compared with those of untreated patients. Limitations: Some limitations include potential confusion via indication bias; causal statements about these associations cannot be made due to the observational nature of this study. Conclusions: In this prospective NDD-CKD cohort study, the administration of sevelamer was independently associated with lower all-cause and cardiovascular mortality, suggesting that non-calcium-based phosphate binders might be the first-line therapy for phosphate lowering in this population. Further interventional studies clarifying the risks and benefits of phosphate binders in NDD-CKD are warranted.

OBJECTIVE: Sevelamer is a phosphate-binding resin implicated in gastrointestinal (GI) injury. This study aimed to investigate the role of sevelamer in GI injury among chronic kidney disease (CKD) patients.
RESULTS: The study included 17 CKD patients (cases) with and 18 CKD patients (comparisons) without sevelamer crystals in specimens. All cases were on sevelamer. Six comparison patients were also taking sevelamer, but crystals were absent in tissue sections. The comparison group was thus subclassified into patients who were and were not taking sevelamer. The frequency of underlying disorders was similar between two groups, including hypertension (cases = 82%; comparisons = 78%) and diabetes mellitus (cases = 53%, comparisons = 50%). The most common presentation was GI bleeding (cases = 41%, comparisons = 33%). Predominant histological patterns were also similar, with ulcers (cases = 42%; comparisons = 39%) and acute ischaemia (cases = 35%; comparisons = 28%) being predominant in both cohorts. Of note, sevelamer was present with amyloidosis and cytomegalovirus in one study case each. Two study patients who continued sevelamer had follow-up biopsies; one showed persistent ulceration and the other appeared normal. Crystals were absent in both.
CONCLUSIONS: GI injury in CKD patients in both groups had similar features regardless of presence of sevelamer, suggesting that it adheres to tissue rather than causes injury. The study highlights other histologically identifiable causes of intestinal injury, as well as injuries unassociated with sevelamer in patients undergoing therapy. Therefore, physicians should be cautious in attributing GI injuries to sevelamer to avoid overlooking other causes and unnecessary treatment discontinuation.

Enarodustat is an orally available hypoxia-inducible factor-prolyl hydroxylase inhibitor which can correct the erythropoietic capacity and improve anemia in chronic kidney disease. Sevelamer carbonate, a non-calcium-based polymeric resin, is one of the commonly prescribed agents for the management of hyperphosphatemia in patients undergoing hemodialysis. This was an open-label, crossover study in healthy male subjects (N = 12) that evaluated the effect of sevelamer carbonate (2400 mg) on the bioavailability of enarodustat (25 mg) when the 2 drugs were administered together (Treatment B) or when enarodustat was administered 3 hours after (Treatment C) or 1 hour before (Treatment D) sevelamer carbonate compared to enarodustat alone (Treatment A). With coadministration of the 2 drugs (Treatment B), enarodustat Cmax and AUCinf reductions were 53% and 45%, respectively. For Treatment C, Cmax and AUCinf reductions were 11% and 6%, respectively, and for Treatment D the corresponding values were 8% and 20%. Thus, coadministration of enarodustat and sevelamer carbonate resulted in a substantial reduction (≈50%) in the oral bioavailability of enarodustat. However, the interaction was substantially mitigated by staggering the administration of enarodustat and sevelamer carbonate. Administration of 4 single oral doses of enarodustat 25 mg, with or without sevelamer carbonate, were safe and well tolerated in this study.