Acute oxalate nephropathy: exploring the role of excess dietary oxalate intake

Acute oxalate nephropathy is a rare but important cause of severe acute kidney injury. We report here two cases presenting as unexplained AKI which were confirmed histologically to be due to acute oxalate nephropathy. Dietary oxalate or its precursor vitamin C was the cause of oxalate exposure in both of these cases. While one patient recovered, another continued to need dialysis and succumbed to underlying metastatic cancer. This cause should be suspected in all patients presenting with unexplained AKI, and detailed history about dietary intake of oxalate or vitamin C should be inquired.

Oxalate nephropathy after pancreaticoduodenectomy: a case report

A 75-year-old male developed acute kidney injury KDIGO stage 3 a few weeks after Whipple surgery was performed for a distal cholangiocarcinoma. Kidney biopsy revealed oxalate nephropathy. This was attributed to post-Whipple malabsorption, poor compliance with pancreatic enzyme replacement therapy, and daily intake of vitamin C supplements. Pancreatic enzyme replacement therapy was resumed and calcium carbonate initiated, with an improvement in glomerular filtration rate. Unfortunately, due to oncological progression, best supportive care was initiated.We review the pathophysiology and conditions predisposing to secondary hyperoxaluria and oxalate nephropathy. This diagnosis should be considered among the main causes of acute kidney injury following pancreatectomy, with important therapeutic implications.

Purslane-induced oxalate nephropathy: case report and literature review

BACKGROUND

The kidney is particularly vulnerable to toxins due to its abundant blood supply, active tubular reabsorption, and medullary interstitial concentration. Currently, calcium phosphate-induced and calcium oxalate-induced nephropathies are the most common crystalline nephropathies. Hyperoxaluria may lead to kidney stones and progressive kidney disease due to calcium oxalate deposition leading to oxalate nephropathy. Hyperoxaluria can be primary or secondary. Primary hyperoxaluria is an autosomal recessive disease that usually develops in childhood, whereas secondary hyperoxaluria is observed following excessive oxalate intake or reduced excretion, with no difference in age of onset. Oxalate nephropathy may be overlooked, and the diagnosis is often delayed or missed owning to the physician's inadequate awareness of its etiology and pathogenesis. Herein, we discuss the pathogenesis of hyperoxaluria with two case reports, and our report may be helpful to make appropriate treatment plans in clinical settings in the future.

CASE PRESENTATION

We report two cases of acute kidney injury, which were considered to be due to oxalate nephropathy in the setting of purslane (portulaca oleracea) ingestion. The two patients were elderly and presented with oliguria, nausea, vomiting, and clinical manifestations of acute kidney injury requiring renal replacement therapy. One patient underwent an ultrasound-guided renal biopsy, which showed acute tubulointerstitial injury and partial tubular oxalate deposition. Both patients underwent hemodialysis and were discharged following improvement in creatinine levels.

CONCLUSIONS

Our report illustrates two cases of acute oxalate nephropathy in the setting of high dietary consumption of purslane. If a renal biopsy shows calcium oxalate crystals and acute tubular injury, oxalate nephropathy should be considered and the secondary causes of hyperoxaluria should be eliminated.

Portulaca Oleracea-associated oxalate nephropathy complicated with an ANCA-positive acute renal injury: A case report

Oxalate nephropathy is a rare disease that can lead to acute kidney injury (AKI). In clinical practice, as renal biopsy is required for diagnosis, physicians often do not have sufficient understanding of this disease. When AKI is associated with positive blood anti-neutrophil cytoplasmic antibodies (ANCA), a diagnosis of renal injury due to ANCA-associated vasculitis is likely to be made, leading to treatment with immunosuppressive therapy. A case of AKI after eating a large quantity of Portulaca oleracea is reported. While blood P-ANCA was positive, both urine proteinuria and urine occult blood were negative. Renal biopsy was performed and identified an acute tubulointerstitial injury: disc-shaped crystals were seen in the lumen of renal tubules that demonstrated birefringence under polarized light, and an oxalate nephropathy was therefore diagnosed. Typical histological changes of an ANCA-associated vasculitis with renal injury such as cellulose-like necrosis and crescent formation were not present. After the patient stopped eating P. oleracea, and following rehydration and hemodialysis, renal function returned to normal. In patients with AKI, the secondary causes of hyperoxalemia should be sought and attention paid to excluding an oxalate nephropathy. In patients with AKI who are ANCA-positive, it is prudent to complete the renal pathological diagnostic process before assuming that the renal injury is caused by an ANCA-associated vasculitis, and before starting hormone and immunosuppressive therapy.

Clinical Outcomes and Histological Patterns in Oxalate Nephropathy due to Enteric and Nonenteric Risk Factors

INTRODUCTION

Current knowledge of risk factors and renal histologic patterns of oxalate nephropathy (ON) not due to primary hyperoxaluria (PH) has been limited to small case series and case reports. Thus, we analyzed and compared clinical risk factors, histologic characteristics, and renal outcomes of patients with biopsy-confirmed ON among a cohort of patients with enteric and nonenteric risk factors.

METHODS

A clinical data repository of native kidney pathology reports from 2009 to 2020 at all Mayo Clinic sites was used to identify 421 ON cases.

RESULTS

After excluding cases in transplanted kidneys or due to PH, 64 cases remained. Enteric risk factors were present in 30 and nonenteric in 34. Roux-en-Y gastric bypass (17) and pancreatic insufficiency (6) were most common in the enteric hyperoxaluria group. In the nonenteric group, vitamin C (7) and dietary oxalate (7) were common, while no apparent risk was noted in 16. Acute kidney injury (AKI) stage III at the time of diagnosis was present in 60%, and 40.6% required dialysis. Patients in the nonenteric group had more interstitial inflammation (p = 0.01), and a greater number of tubules contained intratubular calcium oxalate (CaOx) crystals (p = 0.001) than the nonenteric group. Patients in the enteric group were more likely to have baseline chronic kidney disease (CKD) (p = 0.02) and moderate-to-severe tubulointerstitial fibrosis and atrophy (IFTA) (OR 3.49, p = 0.02). After a median follow-up of 10 months, 39% were dialysis dependent, 11% received a kidney transplant, and 32% died. On univariate analysis, >10 tubules with CaOx crystals, baseline CKD, and AKI requiring dialysis correlated with the risk of dialysis, transplant, or death. On multivariate analysis, only AKI requiring dialysis correlated with adverse renal outcomes.

CONCLUSION

This is the largest cohort study of ON not due to PH. Histologic features differ in patients with enteric versus nonenteric risks. Patients in the enteric group are more likely to have baseline CKD and significant IFTA, while patients in the nonenteric group were more likely to have a greater number of tubules with CaOx crystals and corresponding interstitial inflammation. AKI requiring dialysis at the time of diagnosis was the single most significant predictor of adverse renal outcome.

Kidney transplant dysfunction in a patient with COVID - 19 infection: role of concurrent Sars-Cov 2 nephropathy, chronic rejection and vitamin C-mediated hyperoxalosis: case report

Background

COVID-19 infection in kidney transplant recipients often lead to allograft dysfunction. The allograft injury has various histopathological manifestations. Our case illustrates the unusual combination of allograft rejection, acute kidney injury secondary to oxalate nephropathy and SARS CoV-2 nephropathy as the cause of irreversible allograft failure.

Case presentation

A 56 year old renal allograft recipient presented with a history of fever and diarrhoea for the preceding 4 weeks, tested positive for Sars-CoV2 on nasal swab and was found to have severe allograft dysfunction, necessitating haemodialysis. He subsequently underwent an allograft biopsy, which demonstrated antibody mediated rejection along with the presence of extensive oxalate deposition in the tubules. Ultrastructural examination demonstrated spherical spiked particles in the glomerular capillary endothelium and the presence of tubulo-reticular inclusions suggestive of an active COVID-19 infection within the kidney. The intra-tubular oxalate deposition was considered to be the result of high dose, supplemental Vitamin C used as an immune booster in many patients with COVID − 19 infection in India.

Conclusions

This case highlights the complex pathology that may be seen in following COVID-19 disease and the need for kidney biopsies in these patients to better understand the aetiology of disease.

Case report of oxalate nephropathy in a patient with pancreatic metastases from renal carcinoma

BACKGROUND

Patients with metastatic renal carcinoma frequently have pre-existing renal impairment and not infrequently develop worsening renal function as a complication of their treatment. The presence of pancreatic metastases in patients with metastatic renal carcinoma, often confers a more favourable prognosis and as a consequence this patient group may be exposed to such treatments for more prolonged periods of time. However, the development of renal failure may also be a consequence of the cancer itself rather than its treatment.

CASE PRESENTATION

We present an 84-year-old patient receiving the tyrosine kinase inhibitor (TKI) pazopanib for metastatic renal carcinoma who developed oxalate nephropathy as a consequence of pancreatic exocrine insufficiency resulting from pancreatic metastases.

CONCLUSIONS

This case demonstrates the importance of investigating unexpected toxicities and highlights the potential consequences of pancreatic insufficiency and its sequelae in patients with pancreatic metastases.

Vitamin C-induced oxalate nephropathy in a renal transplant patient related to excessive ingestion of cashew pseudofruit (Anacardium occidentale L.): a case report

Background

Ingestion of vitamin C is generally regarded as harmless. Oxalate nephropathy is an infrequent condition and is characterized by oxalate deposition in the renal tubules, in some cases resulting in acute kidney injury. It can be caused by overproduction of oxalate in genetic disorders and, more frequently, as a secondary phenomenon provoked by ingestion of oxalate or substances that can be transformed into oxalate in the patient.

Case presentation

We present a case of acute oxalate nephropathy in a 59-year-old black male with type 2 diabetes mellitus, who received a kidney transplant 11 years prior. He ingested a large amount of cashew pseudofruit (“cashew apple”) during 1 month and developed acute kidney injury. His previous blood creatinine was 2.0 mg/dL, which increased to 7.2 mg/d; he required hemodialysis. He was subsequently discharged without need for dialysis; 3 months later his blood creatinine stabilized at 3.6 mg/dL.

Conclusions

This pseudofruit is rich in ascorbic acid (vitamin C) and poor in oxalate. Urinary oxalate excretion begins to increase when amounts of ascorbic acid above bodily requirements are ingested, and may provoke acute oxalate nephropathy. The patient’s oxalate acute nephropathy, in this case, was attributed to excessive vitamin C ingestion from the cashew pseudofruit associated with decreased renal function.

A Case of Oxalate Nephropathy: When a Single Cause Is Not Crystal Clear

Hyperoxaluria can result in oxalate nephropathy with intratubular calcium oxalate crystallization and acute tubular injury. Primary inherited enzymatic deficiency or secondary causes such as excessive dietary intake, enteric increased absorption, or high doses of vitamin C, which is metabolized to oxalate, may underlie hyperoxaluria and oxalate nephropathy. We report a case of acute kidney injury due to oxalate nephropathy in a patient using chelating therapy with oral ethylenediamine tetra acetic acid (EDTA), intravenous supplementation with vitamin C, and chronic diarrhea and discuss the potential kidney damage these factors can cause in particular settings. To our knowledge, this is the first report suggesting an association between oral EDTA and oxalate nephropathy.

Steatorrhea and Hyperoxaluria in Severely Obese Patients Before and After Roux-en-Y Gastric Bypass

BACKGROUND AND AIMS

Hyperoxaluria after Roux-en-Y gastric bypass (RYGB) is generally attributed to fat malabsorption. If hyperoxaluria is indeed caused by fat malabsorption, magnitudes of hyperoxaluria and steatorrhea should correlate. Severely obese patients, prior to bypass, ingest excess dietary fat that can produce hyperphagic steatorrhea. The primary objective of the study was to determine whether urine oxalate excretion correlates with elements of fat balance in severely obese patients before and after RYGB.

METHODS

Fat balance and urine oxalate excretion were measured simultaneously in 26 severely obese patients before and 1 year after RYGB, while patients consumed their usual diet. At these time points, stool and urine samples were collected. Steatorrhea and hyperoxaluria were defined as fecal fat >7 g/day and urine oxalate >40 mg/day. Differences were evaluated using paired 2-tailed t tests.

RESULTS

Prior to RYGB, 12 of 26 patients had mild to moderate steatorrhea. Average urine oxalate excretion was 61 mg/day; there was no correlation between fecal fat and urine oxalate excretion. After RYGB, 24 of 26 patients had steatorrhea and urine oxalate excretion averaged 69 mg/day, with a positive correlation between fecal fat and urine oxalate excretions (r = 0.71, P < .001). For each 10 g/day increase in fecal fat output, fecal water excretion increased only 46 mL/day.

CONCLUSIONS

Steatorrhea and hyperoxaluria were common in obese patients before bypass, but hyperoxaluria was not caused by excess unabsorbed fatty acids. Hyperphagia, obesity, or metabolic syndrome could have produced this previously unrecognized hyperoxaluric state by stimulating absorption or endogenous synthesis of oxalate. Hyperoxaluria after RYGB correlated with steatorrhea and was presumably caused by excess fatty acids in the intestinal lumen. Because post-bypass steatorrhea caused little increase in fecal water excretion, most patients with steatorrhea did not consider themselves to have diarrhea. Before and after RYGB, high oxalate intake contributed to the severity of hyperoxaluria.

Chronic dietary oxalate nephropathy after intensive dietary weight loss regimen

Background:

Hyperoxaluria has been associated with nephrolithiasis as well as acute and chronic kidney disease. We present a case of end stage renal failure caused by excessive dietary oxalate intake in a dietary weight loss regimen.

Case Presentation:

A 51-year-old Caucasian male with the past medical history of type 2 diabetes mellitus, gout, hypertension and morbid obesity was referred to the primary care clinic after being found pale and easily fatigued. The patient had lost 36 kg over a 7-month period by implementing exercise and intense dietary measures that included 6 meals of spinach, kale, berries, and nuts. Physical examination revealed a blood pressure of 188/93 mm Hg with sunken eyes and dry mucus membranes. Laboratory workup was notable for blood urea nitrogen of 122 mg/dL, creatinine of 12 mg/dL, and estimated glomerular filtration rate (eGFR) of 4.4 mL/min/1.73m2. Patient denied any history of renal disease or renal stones, or taking herbal products, non-steroidal anti-inflammatory drugs, antifreeze (ethylene glycol), or any type of "diet pills." Family history was unremarkable for any renal diseases. After failing intravenous fluid resuscitation, patient was started on maintenance hemodialysis. Abdominal imaging was consistent with chronic renal parenchymal disease with no evidence of nephrolithiasis. Renal biopsy revealed numerous polarized oxalate crystal deposition and diabetic nephropathy class IIA. At this point the patient was instructed to adopt a low oxalate diet. A 24-hour urine collection was remarkable for pH 4.7, citrate <50 mg, and oxalate 46 mg. Importantly, serum oxalate level was undetectable. Repeat renal biopsy 5 months later while patient was still on maintenance hemodialysis revealed persistence of extensive oxalate crystal deposition. Patient has been referred for evaluation for renal transplantation.

Conclusions:

Clinicians need to maintain a high index of suspicion for dietary hyperoxaluria as a potential etiology for acute or chronic kidney failure, particularly in patients pursuing intensive dietary weight loss intervention

Reversal of Gastric Bypass Resolves Hyperoxaluria and Improves Oxalate Nephropathy Secondary to Roux-en-Y Gastric Bypass

Hyperoxaluria after Roux-en-Y gastric bypass (RYGB) increases the risk for kidney injury. Medical therapies for hyperoxaluria have limited efficacy. A 65-year-old female was evaluated for acute kidney injury [AKI, serum creatinine (Cr) 2.1 mg/dl, baseline Cr 1.0 mg/dl]. She did not have any urinary or gastrointestinal symptoms or exposure to nephrotoxic agents. Sixteen months prior to this evaluation, she underwent RYGB for morbid obesity. Her examination was unremarkable for hypertension or edema and there was no protein or blood on urine dipstick. Kidney biopsy revealed acute tubulointerstitial nephritis with oxalate crystals in tubules. The concurrent finding of severe hyperoxaluria (urine oxalate 150 mg/day) confirmed the diagnosis of oxalate nephropathy. Despite medical management of hyperoxaluria, her AKI worsened. Laparoscopic reversal of RYGB was performed and within 1 month, her hyperoxaluria resolved (urine oxalate 20 mg/day) and AKI improved (Cr 1.7 mg/dl). Surgical reversal of RYGB may be considered in patients with oxalate nephropathy at high risk of progression who fail medical therapy. Physicians need to be aware of the possibility of oxalate nephropathy after RYGB and promptly treat the hyperoxaluria to halt further kidney damage.

Acute oxalate nephropathy associated with orlistat

Background: Obesity is a major world-wide epidemic which has led to a surge of various weight loss-inducing medical or surgical treatments. Orlistat is a gastrointestinal lipase inhibitor used as an adjunct treatment of obesity and type 2 diabetes mellitus to induce clinically significant weight loss via fat malabsorption.

Case Presentation: We describe a case of a 76-year-old female with past medical history of chronic kidney disease (baseline serum creatinine was 1.5-2.5 mg/dL), hypertension, gout and psoriatic arthritis, who was admitted for evaluation of elevated creatinine, peaking at 5.40 mg/dL. She was started on orlistat 120 mg three times a day six weeks earlier. Initial serologic work-up remained unremarkable. Percutaneous kidney biopsy revealed massive calcium oxalate crystal depositions with acute tubular necrosis and interstitial inflammation. Serum oxalate level returned elevated at 45 mm/l (normal <27). Timed 24-hour urine collection documented increased oxalate excretion repeatedly (54-96 mg/24 hour). After five renal dialysis sessions in eighth days she gradually regained her former baseline kidney function with creatinine around 2 mg/dL. Given coexisting proton-pump inhibitor therapy, only per os calcium-citrate provided effective intestinal oxalate chelation to control hyperoxaluria.

Conclusions: Our case underscores the potential of medically induced fat malabsorption to lead to an excessive oxalate absorption and acute kidney injury (AKI), especially in subjects with pre-existing renal impairment. Further, it emphasizes the importance of kidney biopsy to facilitate early diagnosis and treatment.

Weight loss at a high cost: Orlistat-induced late-onset severe kidney disease

AIM

This report describes a case of kidney failure secondary to orlistat, a lipase inhibitor commonly used in the treatment of obesity.

CASE REPORT

An 80-year-old man with type 2 diabetes who was being treated with orlistat developed rapidly progressive kidney failure. Low-grade albuminuria argued against diabetic nephropathy. Renal biopsy showed tubulointerstitial nephritis associated with numerous calcium oxalate crystals. Enteric hyperoxaluria was attributed to the orlistat treatment. The latter was stopped and the patient received calcium supplements. Six months after orlistat withdrawal, oxaluria was normalized and kidney function stabilized.

CONCLUSION

Oxalate nephropathy may result from hyperoxaluria secondary to orlistat treatment. This suggests that kidney function and oxaluria be closely monitored in patients taking orlistat.

Oxalate nephropathy in systemic sclerosis: Case series and review of the literature

OBJECTIVE

To increase awareness of oxalate nephropathy as a cause of acute kidney injury (AKI) among systemic sclerosis patients with small intestinal dysmotility and malabsorption, and to prompt consideration of dietary modification and early treatment of predisposing causes of oxalate nephropathy in this population.

METHODS

Two cases of biopsy-proven oxalate nephropathy were identified among systemic sclerosis patients in the course of direct clinical care. Subsequently, a retrospective search of the Johns Hopkins Pathology databases identified a third patient with systemic sclerosis who developed oxalate nephropathy.

RESULTS

Among the three patients with qualifying biopsies, all three had systemic sclerosis with lower gastrointestinal involvement. All three presented with diarrhea, malabsorption, and AKI. In two of the three patients, diarrhea was present for at least 2 years before the development of AKI; in the third, incidental oxalate nephropathy was noted 3 years before she developed AKI and extensive oxalate nephropathy in the setting of a prolonged mycobacterium avium-intracellulare enteritis. In the first case, oxalate crystals were present by urinalysis months before diagnosis by biopsy; in the second, hyperoxaluria was diagnosed by urine collection immediately after; and in the third, oxalate crystals had been noted incidentally on post-transplant renal biopsy 3 years before the development of fulminant oxalate nephropathy. All three patients died within a year after diagnosis.

CONCLUSIONS

Patients with systemic sclerosis and bowel dysmotility associated with chronic diarrhea and malabsorption may be at risk for an associated oxalate nephropathy. Regular screening of systemic sclerosis patients with small bowel malabsorption syndromes through routine urinalysis or 24-h urine oxalate collection, should be considered. Further studies defining the prevalence of this complication in systemic sclerosis, the benefit of dietary modification on hyperoxaluria, the effect of treating small intestinal bowel overgrowth with antibiotics, and the effectiveness of probiotics, calcium supplements, or magnesium supplements to prevent hyperoxaluria-associated renal disease in these patients, are warranted.

A rare case of hyperoxaluria presenting with acute liver injury and stone-free kidney injury

A 49-year-old woman visited the clinic because of acute hepatitis and acute kidney injury with decreased urine output presenting microscopic hematuria and proteinuria. An abdominal computed tomography revealed a localized, hypoattenuated lesion in a hepatic lateral segment, and kidney biopsy showed oxalate crystal deposition with tubular necrosis. In addition, the patient׳s 24-hour urinary excretion of oxalate was increased. Her kidney and liver injury improved after sessions of hemodialysis, and urinary oxalate excretion was normalized. Major mutations in primary hyperoxaluria have not been proven. A full sequencing of target genes may be helpful to diagnose a rare form of primary hyperoxaluria.