{"title":"Renal Impairment of Proximal Tubular Injury Caused by Red Yeast Rice Supplement: Report of 2 Cases.","authors":"Kazuhiro Takeuchi, Sayumi Kawamura, Yukihiro Wada, Emi Sakamoto, Hideaki Kuno, Shun Sakurabayashi, Tomomi Motohashi, Hiroyuki Okawa, Naohiro Kawamura, Shokichi Naito, Togo Aoyama, Akira Shimizu, Yasuo Takeuchi","doi":"10.1159/000540258","DOIUrl":null,"url":null,"abstract":"<p><strong>Introduction: </strong>Drug-induced tubulointerstitial injury is a common cause of renal impairment. Since the mechanisms of drug-induced tubular injury are diverse, various treatment approaches are needed according to the pathogenesis. Renal biopsy is indispensable to determine not only the pathological diagnosis, but also the underlying mechanism, and to guide appropriate treatment. Most recently, one of the red yeast supplements has been widely highlighted as a novel cause of tubular damage, mainly in Japan and Asia. However, neither detailed pathological findings nor the mechanism of renal impairment has been sufficiently reported.</p><p><strong>Case presentation: </strong>Two cases of renal impairment after taking red yeast supplement internally are presented. Both cases showed renal dysfunction with low uric acid, potassium, and phosphorus levels, characteristic features of Fanconi syndrome. The renal biopsy findings of both cases showed severe injury to the proximal tubules with mild inflammatory cell infiltration. The proximal tubules exhibited diffuse loss of the brush border, flattening, and tubular lumen dilation. Immunofluorescence showed no deposition of immunoglobulin and complement in the glomeruli and tubules. Electron microscopic findings indicated proximal tubular damage without crystal deposition. Moreover, immunohistochemistry using the proximal tubular marker CD10 and a marker for distal tubules including the loop of Henle, E-cadherin, collectively demonstrated that the focus of renal injury in both cases was mainly the proximal tubules.</p><p><strong>Conclusions: </strong>The red yeast rice supplement itself, its metabolized product, or other unknown contaminant components might directly induce proximal tubulopathy rather than an allergic reaction-related tubulointerstitial nephritis.</p>","PeriodicalId":9599,"journal":{"name":"Case Reports in Nephrology and Dialysis","volume":null,"pages":null},"PeriodicalIF":0.7000,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11309756/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Case Reports in Nephrology and Dialysis","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1159/000540258","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/1/1 0:00:00","PubModel":"eCollection","JCR":"Q4","JCRName":"UROLOGY & NEPHROLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Introduction: Drug-induced tubulointerstitial injury is a common cause of renal impairment. Since the mechanisms of drug-induced tubular injury are diverse, various treatment approaches are needed according to the pathogenesis. Renal biopsy is indispensable to determine not only the pathological diagnosis, but also the underlying mechanism, and to guide appropriate treatment. Most recently, one of the red yeast supplements has been widely highlighted as a novel cause of tubular damage, mainly in Japan and Asia. However, neither detailed pathological findings nor the mechanism of renal impairment has been sufficiently reported.
Case presentation: Two cases of renal impairment after taking red yeast supplement internally are presented. Both cases showed renal dysfunction with low uric acid, potassium, and phosphorus levels, characteristic features of Fanconi syndrome. The renal biopsy findings of both cases showed severe injury to the proximal tubules with mild inflammatory cell infiltration. The proximal tubules exhibited diffuse loss of the brush border, flattening, and tubular lumen dilation. Immunofluorescence showed no deposition of immunoglobulin and complement in the glomeruli and tubules. Electron microscopic findings indicated proximal tubular damage without crystal deposition. Moreover, immunohistochemistry using the proximal tubular marker CD10 and a marker for distal tubules including the loop of Henle, E-cadherin, collectively demonstrated that the focus of renal injury in both cases was mainly the proximal tubules.
Conclusions: The red yeast rice supplement itself, its metabolized product, or other unknown contaminant components might directly induce proximal tubulopathy rather than an allergic reaction-related tubulointerstitial nephritis.
期刊介绍:
This peer-reviewed online-only journal publishes original case reports covering the entire spectrum of nephrology and dialysis, including genetic susceptibility, clinical presentation, diagnosis, treatment or prevention, toxicities of therapy, critical care, supportive care, quality-of-life and survival issues. The journal will also accept case reports dealing with the use of novel technologies, both in the arena of diagnosis and treatment. Supplementary material is welcomed.