Evidence against a Single Renal Transport Defect in Cystinuria

SINCE 1810, when Wollaston1 first described a urinary calculus composed entirely of cystine, the pathogenesis of cystinuria has been the subject of controversy. Most current concepts date from the observations that the urine of these patients contains large amounts of lysine, arginine2 , 3 and ornithine4 as well as cystine, whereas the plasma levels of these amino acids are not elevated.3 , 5 , 6 These findings led Dent and Rose3 to conclude that the gross cystinuria characteristic of this disease was due to defective tubular reabsorption rather than impaired metabolism of cystine. The renal clearances of the 4 di-amino acids were shown to be abnormally . . .