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Nephrol Dial Transplant (2012) 27: 1380–1386 doi: 10.1093/ndt/gfr511 Advance Access publication 29 September 2011 Original Articles Amanita poisonings resulting in acute, reversible renal failure: new cases, new toxic Amanita mushrooms Martin Kirchmair1,*, Patrı́cia Carrilho2,*, Rudi Pfab3, Bettina Haberl3, Joana Felgueiras2, Fernanda Carvalho4, José Cardoso5, Ireneia Melo5, José Vinhas2 and Sigrid Neuhauser1 1 Institute of Microbiology, Leopold-Franzens-University of Innsbruck, Innsbruck, Austria, 2Centro Hospitalar de Setubal, Rua Camilo Castelo Branco, Setubal, Portugal, 3Toxikologische Abt., 2. Med. Klinik, Klinikum rechts der Isar, Technische Universität München, München, Germany, 4Hospital Curry Cabral, Lisboa, Portugal and 5Botanic Garden (NMNH) of Lisbon University, Lisbon, Portugal Correspondence and offprint requests to: Martin Kirchmair; E-mail: [email protected] *Both authors contributed equally to this work. Abstract Background. Renal failure as a consequence of eating mushrooms has been reported repeatedly after ingestion of webcaps of the Cortinarius orellanus group. But mushrooms of the genus Amanita can also cause renal failure: Amanita smithiana (North America) and Amanita proxima (Mediterranean area). Here, we discuss poisonings caused by other white amanitas. A German and—independently—two Portuguese patients reported the ingestion of completely white mushrooms with ring. Similar to intoxications with A. smithiana or A. proxima, the clinical picture was characterized by nausea and vomiting 10–12 h after ingestion, severe acute renal failure and mild hepatitis. Renal biopsy showed acute interstitial nephritis and tubular necrosis. Two patients were given temporary haemodialysis. All have fully recovered their renal function. Poisonings caused by mushrooms containing the toxin of A. smithiana were suspected. We tested 20 Amanita species for the presence of this toxin. Methods. Thin layer chromatography was applied to detect A. smithiana nephrotoxin in herbarium specimens using authentic material of A. smithiana as reference. Results. A. smithiana toxin could be detected in Amanita boudieri, Amanita gracilior and in Amanita echinocephala. A. boudieri was collected by the Portuguese patients. A. echinocephala is the only nephrotoxic Amanita growing North of the Alps and is suspected to be the cause of renal failure in the German patient. No A. smithiana toxin was detectable in the nephrotoxic A. proxima. Conclusions. A. boudieri, A. gracilior and A. echinocephala are nephrotoxic. These intoxications are clinically similar to that of A. smithiana, with acute reversible renal failure and mild hepatitis but are different in their clinical picture from Orellanus syndrome characterized by a delayed onset of severe and often irreversible renal failure. Keywords: Amanita boudieri; Amanita echinocephala; mushroom intoxication; thin layer chromatography; toxicology Introduction Collecting wild mushrooms for food has been a longstanding tradition in many European countries; however, edible and toxic species are often confused. Although every ‘mushroom hunters’ guide’ warns its readers against collecting unknown or not well-known fungi, several ‘old wives’ tales’ like testing the fruiting bodies with a silver spoon or checking for insect damage are still used to distinguish edible and poisonous mushrooms. These practices together with tasting unknown edible mushrooms can lead to severe mushroom poisonings because (i) macro-fungi can hardly be reliably identified by comparing pictures in a field guide with specimens from the wild, (ii) the ‘gastronomic value’ of rarer species is often not known and therefore (iii) new poisonous species are discovered occasionally such as those described here. The fungal genus Amanita is divided into seven sections [1]. Mushrooms belonging to the sections Caesareae (Caesar’s Amanita: Amanita caesaria) and Vaginatae (grisette) are edible. Poisonous species can be found in all other sections of the genus (Table 1). The death caps (Amanita phalloides, Amanita virosa; section Phalloideae) contain hepatotoxic cyclopeptides (amatoxins, phalloidin) and cause fulminant hepatical and renal failures that are, if at all, treatable only symptomatically [2]. The section Amanita contains the quintessential toadstool Amanita muscaria (fly agaric). Toxic species of the section Amanita contain the neurotoxins ibotenic acid and muscimol. In the section Validae, slightly toxic mushrooms containing bufotenine and/or haemolytic toxins can be found (false death cap: Amanita citrina, [3]). In sections Lepidella and Amidella, edible and nephrotoxic fungi are known. Among the genus Amanita, the North American Lepidella Amantia smithiana [4–11] and the Mediterranean Amidella Amantia proxima are repeatedly reported to be nephrotoxic [12–17]. Nevertheless, in Europe, Amanita poisonings resulting in renal failure are rare. Most severe renal failures can be traced back to The Author 2011. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved. For Permissions, please e-mail: [email protected] Amanita poisonings resulting in renal failure 1381 Table 1. Occurrence of Amanita smithiana toxin, amatoxins and allenic norleucine (2-amino-4,5-hexadienoic acid) in Amanita species Section Lepidella A. abrupta A. boudieri A. chlorinosma A. echinocephala A. gracilior A. singeri A. smithiana A. strobiliformis A. virgineoidesd A. vittatini Section Amidella A. lepiotoides A. ovoidea A. neoovoidead A. proxima Section Phalloideae A. phalloides A. pseudoporphyriad Section A A. gemmata A. muscaria Section Validae A. citrina Section Cesareae A. cesarea Section Vaginatae A. vaginata Symptomsa A. smithiana toxin Amatoxins/Phallotoxinsb (h) n g n (n) n.k. n e n e – 1 – 1 1 – 1 – – – – – – – – – – – (e) e n n – – – – – – g/n/h n – – 1 p p – – – – p – – e – – e – – 2-amino-4,5-hexadienoic acidc 1 1 1 1 a e, edible; g, gastrointestinal symptoms; h, hepatotoxic; n, nephrotoxic; p, psychoactive; n.k., not known; (): suspected but not proven. Data from [18]. c Data from [19]. d Not tested within this study. b ingestion of poisonous webcaps (Cortinarius spp., Section Orellani; [20, 21]). The Portuguese and German patients reported to have eaten mushrooms resembling white Amanita species. The symptoms were similar to intoxications with A. smithiana or A. proxima but these species could be excluded as discussed below. It became evident that there are more nephrotoxic mushrooms than is currently known. Motivated by these cases, we tested 20 Amanita species for the presence of the A. smithiana nephrotoxin. Materials and methods Material examined Amanita abrupta Peck: IB 2000/0537 (NC). Amanita boudieri Barla: LISU n. 211410 (Portugal). Amanita chlorinosma (Peck) Lloyd: IB 2000/0506 (NC). A. citrina Pers.: no voucher material (Italy). Amanita echinocephala (Vitt.) Quel. (¼ Amanita solitaria sensu auct. mult.): IB 2001/0264 (Italy); IB 1977/0203 (France, Provence); IB 1995/1093 (Austria); IB 2010/0110 (Italy). Amanita gemmata (Fr.) Bertill: LISU n. 211411 (Portugal). Amanita gracilior Bas: IB 1996/0255 (France). Amanita lepiotoides Barla ss. Gilbert, Cetto: IB 1979/0869 (Italy); IB 1980/ 0861 (Italy). A. lepiotoides Barla: IB 1978/0561 (Italy); IB 1977/0311 (Italy); IB 1977/0180 (Italy); IB 1976/0480 (Italy). A. muscaria (L.) Lam. IB 2002/0161 (Austria). Amanita ovoidea (Bull.: Fr.) Quel.: IB 1982/0532 (France); IB 1972/0476 (Israel); MA-Fungi 53355 (Spain); MA-Fungi 68917 (Spain). A. phalloides (Vaill.) Secr: IB 2007/0350 (Austria). A. proxima Dumée: MA-Fungi 74268 (Spain), MA-Fungi 69238 (Spain). Amanita rubescens (Pers. ex Fr.) SF Gray: IB 2005/0624 (Italy). Amanita singeri Bas: IB 1986/0540 (Italy). A. smithiana Bas (¼ A. solitaria sensu Hotson 1936): IB 1995/0357 (OR). IB1991/0995 (OR, voucher material of Pelizzari et al. [22]). Amanita strobiliformis (Paulet ex Vittad.) Bertill. (¼ A. solitaria sensu NCL 1960): IB 2010/0020 (Austria) IB 1998/0504 (Austria). Amanita vaginata (Bull.) Lam.: IB 2005/0647 (Italy). Amanita vittatini (Mor.) Sacc.: IB 1998/0766 (Spain), IB 1998/0830 (Spain). Thin layer chromatography (TLC) Dried basidiomata (0.1 g) were ground and suspended in 1 mL 50% watery methanol for 30 min. This raw extract was filtered through filter paper (Macherey–Nagel Mn 615¼) and 2 lL were spotted onto TLC plates (silica gel 60, Merck 105721) or HPTLC plates (high performance TLC plates; silica gel 60, Merck 105631). Chromatograms were developed using methanol–isopropanol–water–acetic acid–acetic acetate (5:8:12:15:40) as solvent system [22]. The A.smithiana toxin was detected by spraying developed TLC plates with a ninhydrine solution, Ehrlich reagent, Morgan–Elson reagent or anisic aldehyde sulphuric acid according to [23] (Table 2). As reference for the A. smithiana toxin, a raw extract of voucher material of A. smithiana [22] was used because the toxin of A. smithiana is not fully determined and therefore no purified toxin is available. The toxin of A. smithiana can be detected at an Rf of 0.44 and stains orange–red with ninhydrine reagent, yellow with anisic aldehyde—sulphuric acid and yellow with Morgan–Elson reagent [24]. The detection of amatoxins and phalloidine was carried out according to [25]: 2 lL fruiting body extract were spotted onto TLC plates (silica gel 60, Merck 105721) using 2-butoxyethanol-25% watery ammonium hydroxide (7:3) plus 0.2% v/v cinnamic aldehyde as solvent system. Amatoxins can be detected as violet spots at Rf ¼ 0.39 (a-amanitin) or Rf ¼ 0.33 (ß-amanitin) after exposing the chromatogram to HCl vapour. Results Case reports Portugal. A 51-year-old woman and her 47-year-old husband, previously healthy, collected mushrooms in a 1382 M. Kirchmair et al. Table 2. Spray reagents for TLC [23] Reagent Detection of Recipe Staining Morgan–Elson reagent Amino sugars Red Ehrlichs reagent Amines Ninhydrine Amino acids, amines, amino sugars Anisic aldehyde sulphuric acid Sugars, terpenes, steroids, etc. Solution 1: mix 0.5 mL 0.01% KOH in 80% ethanol (w/v) with 10 mL 1% acetylaceton in 1-butanol (v/v) Solution 2: mix 1 g 4-(dimethylamino) benzaldehyde in 30 mL ethanol with 30 mL 36% HCl Heat after spraying with Solution 1 for 5 min at 105C; spray with Solution 2 and heat for 5 min at 90C Solution 1: 1% 4-(dimethylamino) benzaldehyde in 9% methanolic HCl Solution 2: 1% 4-(dimethylamino) benzaldehyde in 96% watery ethanol Heat after spraying with Solution 1; spray with Solution 2 and heat 0.3 g ninhydrine, 100 mL butanol, 3 mL acetic acid Heat at 110C after spraying 0.5 mL anisic aldehyde, 1 mL sulphuric acid in 50 mL glacial acetic acid Heat at 100–105C after spraying small forest, near Lisbon, in Portugal in April 2010. They had two consecutive mushroom meals (dinner and next day’s lunch), ingesting ~500 g of mushrooms in total. The woman complained about anorexia, nausea and vomiting the next day. Five days later, as the complaints still persisted and she additionally noticed weakness and a reduction of diuresis, she went to hospital. On admission, she was normotensive, apparently euvolaemic, afebrile, without relevant findings on physical examination. Initial laboratory tests revealed severe renal failure with creatinine 11.7 mg dL1 (normal: <1.2), blood urea nitrogen (BUN) 68.18 mg dL1 (<18) and a mild hepatic cytolysis with elevation of alanine aminotransferase (ALT) 64 U L1 (10–35). Urine analysis revealed density 1010, pH 5.5, trace blood and protein. Urine microscopy showed >75 white blood cells lL1, 10 red blood cells lL1 and no casts. No pathogens were detectable in urine or stool. Renal ultrasound showed the left kidney to be 123 mm in length and the right kidney 122 mm. Both were echogenic with prominent renal pyramids and no hydronephrosis. No pathogens grew on culture of urine or stool. Haemodialysis was initiated, through a temporary right internal jugular vein dialysis catheter. On the presumption that they had eaten an orellanine-containing mushroom, therapy was started with antioxidant and steroids, as suggested by Kilner et al. [26]. The patient was started on prednisolone 60 mg once a day and oral N-acetylcysteine 600 mg every 6 h. Her renal function improved over the course of the next days, and she became independent of dialysis 5 days after admission (10 days after mushroom ingestion; BUN 45.02 mg dL1 and a creatinine of 2.2 mg dL1). After 2 months, her BUN was 15.9 mg dL1 and creatinine 1.0 mg dL1. The patient’s 47-year-old husband, who had ingested a smaller amount of the mushroom meals, had mild dyspepsia and anorexia, and he did not spontaneously seek for medical help. He was asked to be submitted to clinical and laboratory Various Yellow, orange, red Violet, red, blue, grey, green evaluation. He was also found to have significant renal impairment (BUN 50.0 mg dL1, creatinine 8.6 mg dL1) and mild elevations of ALT (69 U L1) and aspartate aminotransferase (AST) (32 U L1). Leucocytes count 7800 lL1. Urinalysis revealed pH 5.5, density 1020, trace proteins and some erythrocytes and rare leucocytes. Other laboratory tests were normal. His physical examination was unremarkable. He was not given dialysis. Treatment as described above with prednisone and oral Nacetylcysteine was initiated. On the fourth day of admission, a biopsy of his left kidney was made (Figure 1a and b). It showed marked focal interstitial lymphocytic infiltrate with areas of tubular necrosis. The glomeruli appeared normal, apart from one ischaemic glomerulus. Arterioles were normal. Immunofluorescence for immunoglobulin deposits and complement was negative. These aspects were compatible with acute interstitial nephritis. His renal function improved, with serum creatinine of 4.5mg dL1 at day 10 after ingestion of mushrooms. Two months later, his serum creatinine was 0.8 mg dL1. After discharge, the patients re-collected some mushrooms at the original place. Specimens were identified at the Botanic Garden (NMNH) of Lisbon University as A. boudieri (Figure 2a) and A. gemmata. Later, staff from the Botanic Garden accompanied the patients to the field and asked them to point at the mushrooms they had picked. Again, the same two species were collected. Germany. A 55-year-old hitherto healthy woman, native of Italy, was admitted to a Munich hospital, October 1997, 48 h after a meal of ~500 g fresh mushrooms. She had collected the mushrooms herself in a public park near Munich and sautéed them well before eating. She described the mushrooms as white with a flaked hat, white gills, a white ring and a bulb. She claimed to have eaten this type Amanita poisonings resulting in renal failure 1383 Fig. 1. Renal biopsy. (a) Diffuse interstitial infiltrate, normal glomerulus and tubular necrosis (periodic acid-schiff 3250). (b) Diffuse interstitial infiltrate with eosinophils (haematoxylin and eosin 3400). of mushroom all her life and tested its edibility with a silver spoon that did not turn black. Starting 6 h after the meal, she suffered nausea, vomiting and diarrhoea ~10 h after the meal. As the vomiting did not stop the day after the mushroom meal, she was admitted to hospital. There she also complained about visual disturbances. Her physical examination showed no pathologies except for a slight hypertension (160/ 90 mmHg) and dry mucous membranes. The first laboratory tests showed normal liver function tests except for bilirubine 2.3 mg dL1 but an acute renal failure with creatinine 5.2 mg dL1; BUN 48 mg dL1. Other laboratory findings included lactate dehydrogenase 326 U L1 (<240), C-reactive protein 2.3 mg dL1 (<0.5), potassium 2.01 mmol L1 (3.5–5.0), leucocytes 12 500 lL1 (400–9000). At the time of admittance, the diarrhoea and vomiting had stopped, but she soon developed renal failure with preserved water diuresis, mild proteinuria (0.66 g1) with a tubular protein pattern. Tests for anti-nuclear antibodies, extractable nuclear antigen, anti-neutrophil cytoplasmic antibody, circulating immunocomplexes, C3-complement, puumula- and hanta-virus were negative. A renal biopsy was performed 4 days after the meal and showed massive tubular necrosis with eosinophil casts in the tubular lumina a minimal lymphphocytic infiltration of the interstitium. No signs of vascular or glomerular damage were seen. The type of renal lesion may be typical for a toxic damage. A kidney biopsy specimen was tested for the presence of orellanine according to Rohrmoser et al. [21]. No orellanine was detected. The renal function deteriorated so four sessions of haemodialysis were necessary until the renal function fully recovered within 20 days after the meal. Already at admittance, the patient had reported visual disturbances, which did not improve despite the complete recovery of the renal failure. An ophthalmologic examination showed a regular ocular fundus and regular anterior chamber. The functional tests revealed a total loss of colour vision and defects in the upper visual fields in both eyes, fitting for a toxic atrophy of the optic nerve. A follow-up examination after 4 weeks showed normal renal and liver function tests but no improvement of her visus. The cause of the renal failure remained unclear as the Orellanus syndrome had to be excluded because of the negative biopsy sample, the early onset of symptoms and the fact that the patient ate white mushrooms only (Cortinarius orellanus and Cortinarius rubellus are brown). The two white mushrooms that are known to cause similar symptoms—the North American Amanita smithiana and the strict Mediterranean A. proxima—do not grow around Munich but there are records of A. echinocephala (Figure 2b; [27])—a mushroom shown to contain a nephrotoxin in this paper. Detection of A. smithiana toxin in voucher material of Amanita species The toxin of A. smithiana is detectable applying the TLC system described above at an Rf of 0.44, stains orange red with ninhydrine and yellow with Morgan–Elson and Ehrlich reagent [22,24]. The spot at Rf ¼ 0.4 of extracts of voucher material used to identify the A. smithiana toxin by Pelizzari et al. [22] showed identical reactions. Fruiting body extracts of all A. smithiana collections, A. gracilior, A. boudieri and A. echinocephala reacted like the A. smithiana voucher material (Figure 2c). All these species are closely related and belong to the section Lepidella. In extracts of the edible Lepidella A. strobiliformis, the toxin was not detectable. The A. smithiana toxin was not detectable in the nephrotoxic A. proxima, a species of section Amidella and in any other species investigated in this study. Amatoxins and phalloidin could be detected only in A. phalloides. Discussion Several Amanita spp. of the section Lepidella are known to cause renal failure including the North American 1384 M. Kirchmair et al. Fig. 2. Nephrotoxic Amanita spp. (a) Fruitbody of Amantia boudieri (LISU n. 211410). (b) Fruitbody of Amanita echinocephala (IB 2010/0110). (c) Thin layer chromatogram of fruitbody extracts of A. echinocephala (IB 2010/0110), Amanita boudieri (LISU n. 211410), Amanita gemmata (LISU n. 211411), Amanita gracilior (IB 1996/0255), Amanita smithiana (voucher material of Pelizzari et al. [22]), Amanita phalloides (IB 2007/0350). The spot of the A. smithiana toxin is visible at an Rf ¼ 0.44 (arrow) in extracts of A. echinocephala, A. boudieri, A. gracilior, and A. smithiana after spraying with ninhydrine. A. smithiana, which is the best known among these nephrotoxic species [4–11]. The symptoms of our patients conform to those known from A. smithiana intoxications (Table 3). These symptoms start with nausea and vomiting 2–12 h (average 6 h) after the mushroom meal. Renal failure occurs 2–6 days (average 3.5 days) after ingestion. Patients receive supportive treatment, usually requiring temporary haemodialysis, but their prognosis is good. Similar symptoms are reported after ingestion of North and Middle American Amanita thiersii and Amanita nauseosa (both section Lepidella, [1]). There is also a report of renal failure after eating Amanita virgineoides [28], although this mushroom is sold on Chinese markets [1]. In a case of acute renal failure from Taiwan, a fungus morphologically similar to A. smithiana was eaten [29]: 6 h after their meal, the two patients suffered abdominal pain, nausea and vomiting. One patient became anuric a few days later. Also, the second patient developed a minor renal disorder obvious by slightly increased creatinine but no haemodialysis was necessary. Both patients recovered fully. Until now, no nephrotoxic European species of section Lepidella has been identified. The Portuguese patients had symptoms characterized by reversible severe acute renal failure due to acute interstitial nephritis and mild hepatic cytolysis 5 days after ingestion of the mushrooms. The mushrooms responsible for the intoxication could be identified as A. boudieri by examining mushrooms re-collected by the patients. The A. smithiana toxin could be detected in the dried fruiting bodies. The patient from Germany exhibited similar symptoms as the Portuguese patients. Although from this case, no leftovers were available for examination—it is very likely that A. echinocephala was the cause of this poisoning. Fruiting bodies of A. echinocephala contain A. smithiana toxin. It is the only white Lepidella known to occur around Munich [27]. In contrast to all reported cases of poisonings with A. smithiana, the German patient suffered from visual disorders, a symptom that has been reported before only once in connection with mushroom poisoning [30]. The authors report on an A. phalloides intoxication and discussed inter alia, and thereby provoked taurine depletion as possible cause of the visual impairment. The actual significance to our case remains speculative as we did not test the amino acid levels of the patient. Renal failure can also be caused by Amanita spp. section Amidella. Most intoxications are reported from Southern Europe where A. proxima can be confused with the morphologically very similar, edible A. ovoidea [12–17]. Amanita poisonings resulting in renal failure 1385 Table 3. Mushroom intoxications accompanied by renal failure (data summarized from [8,10,13–17,31]) Gastro intestinal symptoms (vomiting, nausea): median delay Renal failure: median delay GPT (3normal value; median) GOT (3normal value; median) Outcome (recovery/chronic renal insufficiency/death) in % Amanita smithiana (n ¼ 9) Amanita proxima (n ¼ 7) Cortinarius orellanus group (n ¼ 82) 6 hours 11 hours 3 days 3.5 days 1.8 1.0 100/0/0 2 days 5.6 2.3 100/0/0 8.5 days 1 (?) 1 (?) 40.3/51.6/8.1 Besides the darker volva of A. proxima, the two species are nearly indistinguishable in their macroscopically and microscopically morphological characters. Spores of both species are elliptical and similar in size. A ‘tennis racket aspect of the spores’ of A. proxima was pictured by Courtin et al. [17]. It is likely that they observed germinating spores of their fresh A. proxima collection and misinterpreted as distinguishing character. The clinical manifestation of A. proxima intoxications is similar to A. smithiana intoxications, but no A. smithiana toxin was detectable in herbarium specimens. The different nature of the A. proxima nephrotoxin(s) needs more attention in future studies. Also, other fungi of the section Amidella have been reported to cause renal failure, a Japanese patient developed gastrointestinal symptoms 9 h after eating Amantia neoovoidea and was hospitalized 2 days later with acute renal failure [32]. However, A. neoovidea is thought to be edible (for example, as tempura or in soups; [1]). Delayed renal failure is also known from members of Section Phalloidea. In the case of A. phalloides, renal failure is probably mediated by toxic cyclopeptides (amatoxins, phalloidin [33]). Amanita pseudoporphyria (section Phalloidea) can cause renal failure with symptoms similar to an A. smithiana intoxication; however, no clear gastrointestinal symptoms develop and the renal symptoms appear later [34]. There is no evidence that A. pseudoporphyria contains amatoxins or phallotoxins, but it contains 2-amino-4, 5-hexadienoic acid, otherwise known from some mushrooms of section Lepidella [35]. A. pseudoporphyria is still considered as member of the section Phalloidae, but according to recent taxonomic analyses, it is possibly a member of Lepidella rather than of Phalloidea [36,37]. The nephrotoxin of Lepidella mushrooms is usually thought to be the allenic norleucine 2-amino-4,5-hexadienoic acid [6,9,29]. This non-protein amino acid has been detected in A. abrupta [38], A. neoovoidea [39], A. pseudoporphyria [35] and A. smithiana [19,40,41]. But, there is evidence that A. smithiana toxin is not identical with the allenic norleucine: (i) the toxicity and/or content of the amino acid in fruiting bodies are too low [41]. The LD50 of 2-amino-4,5-hexadienoic acid is >50 mg kg1 (guinea pig, intraperitoneal) [41], which is high when compared to the fungal nephrotoxin orellanine (LD50 ¼ 8.0 mg kg1 guinea pig, intraperitoneal) [42]. A. smithiana contains 0.1% allenic norleucine [41], while the orellanine content of C. rubellus is 1.2% dry weight1 [21]. The deadly dose rate for an 80 kg person would therefore be 4 kg dried A. smithiana mushrooms (~400 fruiting bodies). (ii) In the hepatotoxic (but not nephrotoxic) A. abrupta [38], the allenic norleucine was detected, but the A. smithiana toxin could not be detected in our study. The exact nature of A. smithiana toxin remains unclear. The toxin reacts with ninhydrine on TLC, which argues for amino groups. Pellizari et al. [22] misinterpreted the toxin as an amino sugar, which can be detected by the specific red staining with Morgan– Elson reagent [23] but the A. smithiana toxin stains yellow [24]. Future studies are necessary to elucidate the nature and the mode of action of the toxin. It is important for the medical community to be aware of nephrotoxic mushrooms of the genus Amanita. We identified three nephrotoxic species besides A. smithiana and A. proxima: the strictly Mediterranean species A. boudieri and A. gracilior and A. echinocephala known from temperate regions all over Europe. The ‘Amanita nephrotoxic syndrome’ is characterized by an early onset of gastrointestinal symptoms, mild hepatic damage and severe but reversible acute renal failure due to acute interstitial nephritis (Table 3). It must be separated from the well-known Orellanus syndrome, characterized by the absence of gastrointestinal symptoms and a delayed onset of renal failure with a very bad prognosis. Acknowledgements. We thank Frank H. Gleason for constructive comments and suggestions during the preparation of this paper. 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