Persistent Leukocyturia Was a Clue to Diagnosis of Cystinuria in a Female Patient

Cystinuria (OMIM 220100) is characterized by the defective reabsorption of cysteine, lysine, ornithine, and arginine in the brush border membrane of proximal renal tubule and in the epithelial cells of the gastrointestinal tract. High cystine concentration causes the formation of recurring renal stones. Two genes, SLC3A1 (rBAT) and SLC7A9 (BAT1), are known to be responsible.1,2 Although leukocyturia is an important sign of urinary tract infection (UTI), we report the case of a female patient with cystinuria that was detected owing to continuous leukocyturia.