Mechanisms of star fruit-induced acute renal failure

Death associated with ingestion of starfruit (Averrhoa carambola) in a patient with chronic kidney disease

We detail a case of a 74-year-old female with a history of chronic kidney disease (CKD) and diabetes mellitus (DM) who initially presented to the Emergency Department (ED) with intractable hiccups after ingesting two whole starfruit (SF) and quickly became critically ill while in the ED. Our patient was admitted and received several rounds of hemodialysis, but efforts proved futile, as the patient expired during her hospital course. To the best of our knowledge, this is the first fatality reported due to SF ingestion in the U.S, and highlights the need for both a better understanding of SF intoxication and clearer guidelines and timing for treatment. Due to the increased mortality of patients who consume SF with a medical history of CKD or DM, it is prudent that Emergency Physicians are familiar with the clinical presentation and management options for SF toxicity.

Acute kidney injury associated with consumption of starfruit juice: A case report

BACKGROUND

This study aims to highlight the potential serious complications of acute kidney injury (AKI) resulting from the consumption of excessive amounts of starfruit, a common traditional remedy.

CASE SUMMARY

A 78-year-old male with a past medical history of hypertension, diabetes mellitus and hyperlipidemia without prior nephropathy presented to the emergency department (ED) with hiccups, nausea, vomiting and generalized weakness. In the preceding 1 wk, he had consumed 3 bottles of concentrated juice self-prepared from 1 kg of small sour starfruits. His serum creatinine was noted to be 1101 μmol/L from baseline normal prior to his ED visit. He was diagnosed with AKI secondary to excessive starfruit consumption.

CONCLUSION

Consumption of starfruit can cause acute renal failure, with a good outcome when promptly identified and treated.

Nephrotoxicity and neurotoxicity following star fruit (Averrhoa carambola) ingestion: a narrative review

In recent times, star fruit (Averrhoa carambola) nephrotoxicity and neurotoxicity have been increasingly reported, both in individuals with pre-existing renal disease and those with previously normal renal function. We summarise the clinical findings of star fruit toxicity in humans and outline the important pathogenetic insights provided by animal studies. Google Scholar, EMBASE, Scopus and PubMed were searched from 1995 through July 2020 for case reports/series on renal or neurological manifestations of star fruit toxicity in humans and mechanisms of star fruit toxicity in animal studies. Ten case series and 28 case reports in humans (total number of individuals=136) were included and 8 animal studies were analysed. Ninety-four (69.1%) patients had prior renal impairment. Renal histology showed acute oxalate nephropathy with tubulointerstitial nephritis or tubular necrosis. Neurotoxicity manifestations ranged from hiccups to status epilepticus. Oxalate and caramboxin are considered the main substances causing nephrotoxicity and neurotoxicity. Caramboxin inhibits GABA binding and activates the glutamatergic receptors. Haemodialysis improved outcomes in neurotoxicity. Nephrotoxicity and neurotoxicity need to be looked for with star fruit toxicity, both in individuals with abnormal or normal renal function. Once star fruit intoxication is identified, early renal replacement therapy should be considered. Further studies on the mechanisms of star fruit toxicity are needed.

Standardization of experimental model regarding star fruit intoxication in Wistar rats suffering with nephropathy

Purpose

To present a model to reproduce the clinical condition, in order to better understand the pathophysiology of neurological impairment related to intoxication.

Methods

Twenty-five Wistar rats were used and divided into five groups: Shaw group (WHI), water gavage group (WGV), star fruit gavage group (SGV), nephropathic group with water gavage (NPW), nephropathic group with star fruit gavage (NPS).Nephropathic groups were submitted to surgery, developing nephropathy. After surgery, they received preestablished gavage with star fruit juice or water. The electroencephalographic records were evaluated in the experimental nephropathic group that received gavage of star fruit juice.

Results

To assess the induction of neurotoxicity using electroencephalographic data, the NPS group demonstrated the presence of epileptic seizures associated with star fruit intoxication.

Conclusions

The experimental model herein presented was adequate to reproduce the clinical condition experienced by nephropathic patients who ingest star fruit juice, establishing, thus, an experimental model utterly important for the study of the neurological toxicity process.

Acute Kidney Injury Following Star Fruit Ingestion: A Case Series

Star fruit (Averrhoa carambola) is a popular fruit in many tropical countries, including Sri Lanka. It is rich in oxalic acid, which is nephrotoxic in higher concentrations. The development of both acute (AKI) and chronic kidney injury after oxalate nephropathy is often underrecognized. Here we discuss the risk factors, clinical features, treatment, and outcomes of 4 patients who developed AKI after star fruit ingestion. Baseline clinical characteristics, the amount of star fruit ingested, clinical presentation, investigation, and outcome of the patients (ages 28, 50, 54, and 55 y; all male) were traced. More common symptoms of acute star fruit intoxication were nausea, vomiting, and abdominal and back pain, followed by low urine output and high serum creatinine over hours to days. Urinary analysis of all patients demonstrated oxalate crystals. Histopathologic examination of renal tissues of all 4 patients revealed acute tubular damage with calcium oxalate crystals, interstitial edema, and inflammatory cellular infiltration. The presence of calcium oxalate crystals was further confirmed with the brilliant birefringence seen under polarized light. Two patients needed intermittent hemodialysis over a week owing to oliguria and uremia. The other 2 patients did not require hemodialysis and had improvement of renal function with supportive treatment. All had high renal function on discharge but were back to normal within a month. This study highlights AKI as a serious complication of star fruit ingestion. The type and quantity of star fruit ingested and some patient factors may play a role in the pathogenesis of AKI. Public education about this serious uncommon complication is important.

Acute nephrotoxicity and neurotoxicity associated with concentrated star fruit juice consumption

Star fruit toxicity has been hugely described in patients with chronic kidney disease, either on conservative or renal replacement therapy. This is a case report of a man, without prior kidney or neurological dysfunction, who appeared to develop nephrotoxicity and neurotoxicity less than 12 hours after drinking concentrated star fruit juice (approximately 20 units of the fruit). He received timely renal replacement therapy and renal function fully recovered after discharge.

Mechanisms of star fruit (Averrhoa carambola) toxicity: A mini-review

The star fruit (Averrhoa carambola) is consumed in high amounts in Asia and Central/South America. It contains oxalic acid and caramboxin. In some individuals, its ingestion may lead to nephrotoxicity and neurotoxicity. The nephrotoxic effect is due to oxalate deposition in renal tubules resulting in acute tubular necrosis and interstitial nephritis. Although uraemic encephalopathy secondary to acute kidney injury may play a role, a shift to an excitatory state of the central nervous system (CNS) by caramboxin through activation of excitatory neuroreceptors and inhibition of GABA receptors leads to mental confusion, seizures and status epilepticus seen with star fruit intoxication. In this mini-review, we discuss the mechanisms of star fruit-related toxicity.

Dietary Oxalate Intake and Kidney Outcomes

Oxalate is both a plant-derived molecule and a terminal toxic metabolite with no known physiological function in humans. It is predominantly eliminated by the kidneys through glomerular filtration and tubular secretion. Regardless of the cause, the increased load of dietary oxalate presented to the kidneys has been linked to different kidney-related conditions and injuries, including calcium oxalate nephrolithiasis, acute and chronic kidney disease. In this paper, we review the current literature on the association between dietary oxalate intake and kidney outcomes.

C-Fos expression in epileptogenic areas of nephropathic rats undergoing star fruit poisoning

Purpose

Studies have demonstrated that star fruit consumption by nephropathic patients triggers severe neurotoxic effects that can lead to convulsions or even death. Brain areas likely susceptible to star fruit poisoning have not been investigated. The objective of the present study was to map possible epileptogenic areas susceptible to star fruit intoxication in nephropathic rats.

Methods

The study analyzed 25 rats (5 groups). Rats in the experimental group underwent bilateral ureteral obstruction surgery and orogastric gavages with star fruit juice. An electroencephalogram was used to confirm convulsive seizures. Urea and creatinine levels were used to confirm the uremia model. Immunohistochemical analysis was used to map cells with c-Fos protein (c-Fos+ cells) to identify brain areas with increased neuronal activity. Control groups included non-nephropathic and nephropathic rats that did not receive star fruit.

Results

A statistically significant increase (p<0.01) in c-Fos+ cells was noted in nephropathic animals receiving star fruit juice compared to control groups, in brain areas commonly related to epileptogenic neural circuits including the hippocampus, amygdala, rhinal cortex, anterior cingulate area, piriform area, and medial dorsal thalamus.

Conclusion

These data corroborate the neurotoxic capacity of star fruit in nephropathic patients.

Acute Kidney Injury with Neurological Features: Beware of the Star Fruit and its Caramboxin

Star fruit (Averrhoa carambola) is a well-known product in tropical countries. There are few reports published in literature with acute kidney injury due to oxalate induced nephropathy. However, none of them have an important neurological feature. We present a case of a 51-year-old male with paresis and altered mental status. Screening for neurological diseases such as stroke, Guillain-Barre, meningitis and encephalitis were negative. In the evolution, he developed acute kidney failure and was submitted to 4 dialysis sessions. After talking to the family, we discovered he had ingested over 50 star fruits prior to the acute neurologic deficits. He recovered renal function so a renal biopsy was not required. Physicians should actively look for star fruit ingestion history in patients presenting with unexplained acute kidney injury with or without neurological features. Besides, taking star fruit in a large amount, accompanied by an empty stomach and dehydrated state, is a risk factor for neurotoxicity.

Worsening of Oxidative Stress, DNA Damage, and Atherosclerotic Lesions in Aged LDLr-/- Mice after Consumption of Guarana Soft Drinks

BACKGROUND

Excessive consumption of soft drinks (SD) has become a health problem worldwide due to its association with related cardiovascular diseases. We investigated the possible impacts associated with the consumption of Brazilian guarana (normal and zero) SD in dyslipidemic mice, thus mitigating potential clinical confounders such as poor-quality diet, lifestyle, body composition, and/or comorbidities.

METHODS

Sixteen-month-old LDLr-/- mice were divided into the following groups: (1) control; (2) GSD: normal guarana SD; and (3) Z-GSD: zero guarana SD. All were fed ad libitum, and blood pressure was measured noninvasively. After 8 weeks, aorta, blood, liver, and stomach samples were collected for histological and biochemical analyses.

RESULTS

Guarana soft drinks increased atherosclerosis (~60%) and were associated with hypercholesterolemia, hypertension, oxidative stress, DNA fragmentation, and apoptosis (~2-fold) of blood cells, besides presenting an increase in liver and gastric damage even in normoglycemia. Interestingly, Z-GSD did not cause the aforementioned changes, except in hemodynamic and renal parameters.

CONCLUSIONS

Chronic administration of GSD is prooxidative, compromising the cardiovascular, gastric, and hepatic systems; the effects are due at least in part to free sugar consumption but not to guarana extract per se.

Star fruit nephrotoxicity: a case series and literature review

Background

Star fruit is a popular medicinal fruit in the tropics. Its hypoglycaemic properties are considered useful in achieving glycaemic control in diabetes. Star fruit induced nephrotoxicity is a rare cause of acute kidney injury in individuals with both normal and reduced baseline renal function. We present three cases of acute kidney injury due to star fruit nephrotoxicity from Sri Lanka, and discuss the published literature on this topic.

Case presentation

Three Sri Lankan patients, all with a background of diabetes, presented to us with acute nausea and anorexia following recent consumption of star fruit. Two patients complained of diarrhoea and one patient complained of intractable hiccoughs. They all had elevated serum creatinine on admission. Two were known to have normal baseline serum creatinine levels. On renal biopsy two had evidence of oxalate crystal deposition. One did not show crystal deposition but had acute interstitial nephritis for which no alternate cause could be identified. Two were treated with short courses of prednisolone and two required acute haemodialysis. All recovered renal function, with both patients with known baselines approaching their premorbid serum creatinine levels.

Conclusion

Consumption of star fruit, especially on an empty stomach or in a state of dehydration may precipitate acute kidney injury. A history of star fruit ingestion must be actively looked for in patients presenting with unexplained acute kidney injury. The use of star fruit as a therapy for diabetes should be discouraged.

Nutrients Turned into Toxins: Microbiota Modulation of Nutrient Properties in Chronic Kidney Disease

In chronic kidney disease (CKD), accumulation of uremic toxins is associated with an increased risk of death. Some uremic toxins are ingested with the diet, such as phosphate and star fruit-derived caramboxin. Others result from nutrient processing by gut microbiota, yielding precursors of uremic toxins or uremic toxins themselves. These nutrients include l-carnitine, choline/phosphatidylcholine, tryptophan and tyrosine, which are also sold over-the-counter as nutritional supplements. Physicians and patients alike should be aware that, in CKD patients, the use of these supplements may lead to potentially toxic effects. Unfortunately, most patients with CKD are not aware of their condition. Some of the dietary components may modify the gut microbiota, increasing the number of bacteria that process them to yield uremic toxins, such as trimethylamine N-Oxide (TMAO), p-cresyl sulfate, indoxyl sulfate and indole-3 acetic acid. Circulating levels of nutrient-derived uremic toxins are associated to increased risk of death and cardiovascular disease and there is evidence that this association may be causal. Future developments may include maneuvers to modify gut processing or absorption of these nutrients or derivatives to improve CKD patient outcomes.

N-acetylcysteine protects against star fruit-induced acute kidney injury

Background: Star fruit (SF) is a popular fruit, commonly cultivated in many tropical countries, that contains large amount of oxalate. Acute oxalate nephropathy and direct renal tubular damage through release of free radicals are the main mechanisms involved in SF-induced acute kidney injury (AKI). The aim of this study was to evaluate the protective effect of N-acetylcysteine (NAC) on SF-induced nephrotoxicity due to its potent antioxidant effect.

Materials and methods: Male Wistar rats received SF juice (4 mL/100 g body weight) by gavage after a 12 h fasting and water deprivation. Fasting and water deprivation continued for 6 h thereafter to warrant juice absorption. Thereafter, animals were allocated to three experimental groups: SF (n = 6): received tap water; SF + NAC (n = 6): received NAC (4.8 g/L) in drinking water for 48 h after gavage; and Sham (n = 6): no interventions. After 48 h, inulin clearance studies were performed to determine glomerular filtration rate. In a second series of experiment, rats were housed in metabolic cages for additional assessments.

Results: SF rats showed markedly reduced inulin clearance associated with hyperoxaluria, renal tubular damage, increased oxidative stress and inflammation. NAC treatment ameliorated all these alterations. Under polarized light microscopy, SF rats exhibited intense calcium oxalate birefringence crystals deposition, dilation of renal tubules and tubular epithelial degeneration, which were attenuate by NAC therapy.

Conclusions: Our data show that therapeutic NAC attenuates renal dysfunction in a model of acute oxalate nephropathy following SF ingestion by reducing oxidative stress, oxaluria, and inflammation. This might represent a novel indication of NAC for the treatment of SF-induced AKI.

Addition of calcium compounds to reduce soluble oxalate in a high oxalate food system

Spinach (Spinacia oleracea L.) is often used as a base vegetable to make green juices that are promoted as healthy dietary alternatives. Spinach is known to contain significant amounts of oxalates, which are toxic and, if consumed regularly, can lead to the development of kidney stones. This research investigates adding 50-500mg increments of calcium carbonate, calcium chloride, calcium citrate and calcium sulphate to 100g of raw homogenates of spinach to determine whether calcium would combine with the soluble oxalate present in the spinach. Calcium chloride was the most effective additive while calcium carbonate was the least effective. The formation of insoluble oxalate after incubation at 25°C for 30min is a simple practical step that can be incorporated into the juicing process. This would make the juice considerably safer to consume on a regular basis.

Acute kidney injury associated with ingestion of star fruit: Acute oxalate nephropathy

Starfruit (Averrhoa carambola) and its juice are popular in the Indian subcontinent as an indigenous medicine. Oxalate concentration in this fruit and it's freshly prepared juice is very high. We present a report of patients presenting with acute kidney injury due to oxalate nephropathy admitted in a single center. All patients had history of ingesting star fruit. Patients became symptomatic after 10-12 h of eating and main symptoms were pain abdomen and decrease in urine output. Three patients needed hemodialysis. All improved with complete renal recovery. Taking star fruit in large amount on an empty stomach and in a dehydrated state is a risk factor for nephrotoxicity.

Star fruit toxicity: a cause of both acute kidney injury and chronic kidney disease: a report of two cases

Background

Star fruit (Averrhoa carambola) is commonly consumed as a herbal remedy for various ailments in tropical countries. However, the dangers associated with consumption of star fruit are not commonly known. Although star fruit induced oxalate nephrotoxicity in those with existing renal impairment is well documented, reports on its effect on those with normal renal function are infrequent. We report two unique clinical presentation patterns of star fruit nephrotoxicity following consumption of the fruit as a remedy for diabetes mellitus—the first, in a patient with normal renal function and the second case which we believe is the first reported case of chronic kidney disease (CKD) due to prolonged and excessive consumption of star fruits.

Case presentation

The first patient is a 56-year-old female diabetic patient who had normal renal function prior to developing acute kidney injury (AKI) after consuming large amount of star fruit juice at once. The second patient, a 60-year-old male, also diabetic presented with acute on chronic renal failure following ingestion of a significant number of star fruits in a short duration with a background history of regular star fruit consumption over the past 2–3 years. Both had histologically confirmed oxalate induced renal injury. The former had histological features of acute tubulo-interstitial disease whilst the latter had acute-on-chronic interstitial disease; neither had histological evidence of diabetic nephropathy. Both recovered over 2 weeks without the need for haemodialysis.

Conclusion

These cases illustrate the importance of obtaining the patient’s detailed history with respect to ingestion of herbs, traditional medication and health foods such as star fruits especially in AKI or CKD of unknown cause.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-015-1640-8) contains supplementary material, which is available to authorized users.

Nephropathy in dietary hyperoxaluria: A potentially preventable acute or chronic kidney disease

Hyperoxaluria can cause not only nephrolithiasis and nephrocalcinosis, but also renal parenchymal disease histologically characterized by deposition of calcium oxalate crystals throughout the renal parenchyma, profound tubular damage and interstitial inflammation and fibrosis. Hyperoxaluric nephropathy presents clinically as acute or chronic renal failure that may progress to end-stage renal disease (ESRD). This sequence of events, well recognized in the past in primary and enteric hyperoxalurias, has also been documented in a few cases of dietary hyperoxaluria. Estimates of oxalate intake in patients with chronic dietary hyperoxaluria who developed chronic kidney disease or ESRD were comparable to the reported average oxalate content of the diets of certain populations worldwide, thus raising the question whether dietary hyperoxaluria is a primary cause of ESRD in these regions. Studies addressing this question have the potential of improving population health and should be undertaken, alongside ongoing studies which are yielding fresh insights into the mechanisms of intestinal absorption and renal excretion of oxalate, and into the mechanisms of development of oxalate-induced renal parenchymal disease. Novel preventive and therapeutic strategies for treating all types of hyperoxaluria are expected to develop from these studies.

Oxalate nephropathy due to 'juicing': case report and review

A patient presented with oxalate-induced acute renal failure that was attributable to consumption of oxalate-rich fruit and vegetable juices obtained from juicing. We describe the case and also review the clinical presentation of 65 patients seen at Mayo Clinic (Rochester, MN) from 1985 through 2010 with renal failure and biopsy-proven renal calcium oxalate crystals. The cause of renal oxalosis was identified for all patients: a single cause for 36 patients and at least 2 causes for 29 patients. Three patients, including our index patient, had presumed diet-induced oxalate nephropathy in the context of chronic kidney disease. Identification of calcium oxalate crystals in a kidney biopsy should prompt an evaluation for causes of renal oxalosis, including a detailed dietary history. Clinicians should be aware that an oxalate-rich diet may potentially precipitate acute renal failure in patients with chronic kidney disease. Juicing followed by heavy consumption of oxalate-rich juices appears to be a potential cause of oxalate nephropathy and acute renal failure.

Nephrotoxicity of alternative medicine practice

The use of alternative medicine is highly prevalent around the world; in many areas, this is so because of lack of access to, or trust in, Western medicine, and also because they are considered "natural" and therefore safe. The kidney is an organ vulnerable to toxic insults by virtue of its anatomy and function. Reports of nephrotoxicity associated with alternative medicine use encompass all forms of renal dysfunction, ranging from electrolyte abnormalities and proteinuria to acute and CKD, renal failure, and death. In countries where intensive care and dialysis support are not available, mortality is high. Mechanisms of alternative medicine-associated kidney injury include direct nephrotoxicity, which may be augmented by underlying predisposing conditions such as dehydration; contamination, or adulteration of remedies; inappropriate use or preparation of a remedy; or interactions with other medications. The use of alternative medicines is underreported to clinicians. Because many patients strongly believe in the powers of alternative medicines, it is important that alternative medicines not be demonized as a whole, but that their use and consequences be closely observed and reported to build a more comprehensive understanding of their impact in our clinical practice and to foster research on the potential harm or, in some cases, possible benefits.

Novel nephrotoxins

Drug and xenobiotic toxicity is an important cause of kidney injury, especially in vulnerable patients. Nephrotoxic syndromes include functional disorders; vascular injury, such as thrombotic microangiopathy; glomerular injury resulting in nephrotic syndrome or glomerulonephritis; acute tubular necrosis; acute interstitial nephritis; and crystalopathy/nephrolithiasis. Recently reported nephrotoxins are reviewed in the context of these syndromes of kidney injury.

Herbal medicines and chronic kidney disease

Alternative and indigenous systems of medicine are popular amongst the poorer sections of society in the developing world. Their use in the developed world has also increased in recent times. The source and composition of these medicines vary in different parts of the world, but herbs and other botanicals are central to these systems. Largely outside the ambit of regulatory control, herbal remedies are prepared by quasi-trained herbalists and not tested for safety. Toxicity can occur when a herb with unknown toxicity is consumed, incorrect identification leads to substitution of an innocuous herb with a toxic one, preparations are contaminated with toxic non-herbal compounds or when a herb potentiates the nephrotoxic effect of a conventional therapy. Renal injury has been reported in association with several herbs. The best-known herb-induced chronic kidney disease (CKD) is aristolochic acid nephropathy. The condition is characterized by progressive interstitial nephritis, with a proportion of patients developing urothelial malignancies. The toxic compound is aristolochic acid (AA); AA-DNA adducts have been identified in the renal and urothelial tissues. Recent evidence suggests that AA also contributes to the development of Balkan endemic nephropathy. The role of herbs has been postulated in the development of CKD in other parts of the developing world, especially amongst the rural population. Public awareness and regulation of use of herbal medicines are required to eradicate this entity from the community.

Acute kidney injury associated with the use of traditional medicines

The use of traditional medicine is common worldwide, with rates of use of over 80% in some populations. Considering the large number of people using traditional remedies throughout the world, it does seem that most do so without major adverse effects. Nevertheless, many folk medicines can cause kidney injury. Drug-induced nephrotoxicity reportedly contributes to up to 26% of cases of hospital-acquired acute kidney injury (AKI) and 18% of cases of community-acquired AKI globally, and folk remedies account for up to 35% of cases of AKI in the developing world. The kidney is highly susceptible to toxic insults because its intrinsic functions expose it to exceptionally high concentrations of any particular toxic substance. Clinical syndromes of nephrotoxicity can be defined according to the predominant regions of the kidney affected by the toxin, and reversibility of the injury is likely related to the severity and nature of the injury and also to the duration of toxin exposure. In countries with well-developed health-care systems, a large proportion of patients with nephrotoxicity will recover at least some renal function with adequate supportive care and dialysis. Health-care practitioners in all countries should be aware of the high prevalence of the use of alternative therapies and should be proactive in obtaining this information from patients. In poorer countries, where large proportions of the population rely on traditional medicine, attempts should be made to integrate traditional healers into the health-care system.