Three Cases of Red Yeast Rice-Containing Supplement-Induced Acute Kidney Injury and Fanconi Syndrome.

Japan has recently faced a public health crisis owing to "Beni Koji Choleste Help," a product marketed as a dietary supplement. It is made from red yeast rice and has cholesterol-lowering effects. Following the identification of the first case of acute kidney injury (AKI) caused by the product, 76 possibly related deaths and 492 hospitalizations have been reported in Japan. We herein demonstrate three cases of AKI with renal tubular acidosis and Fanconi syndrome following consumption of the product for 2 weeks to 7 months. Kidney biopsy revealed diffuse tubular injury, tubular cell flattening, loss of brush border, sparse debris, and cast formation containing periodic acid-Schiff- and silver stain-positive fluffy material in the tubular lumens with interstitial cell infiltration, together with mild fibrosis. Electron microscopy revealed fluffy materials in the tubular lumen surrounded by necrotic tubular cell debris and intracellular contents. Discontinuation of the supplement and the treatment with prednisolone improved kidney function and Fanconi syndrome. Longitudinal monitoring and surveys are required to detect and prevent the progression to chronic kidney disease in people who have consumed "Beni Koji Choleste Help."