Hemodialysis in a Patient With Cystinosis

THE PATHOGENESIS of cystine crystal formation in cystinosis (Lignac-Fanconi disease) is unknown. 1-3 Baar and Bickel proposed that cystinosis is a disorder of intracellular protein metabolism, and cystine crystalizes intracellularly at the site of its formation. 2 More recently, Worthen and Good 3 postulated that cystine crystal formation is also due to an elevated blood concentration of cystine, 4 leading to a gradual deposition of supersaturating amounts of cystine in the cornea and renal tubule and to phagocytosis by the cells of the reticuloendothelial system. Woods et al, in a study of the effects of hemodialysis on uremic patients, reported a 22% to 29% removal of free plasma amino acids with each passage of blood through the artificial kidney during a six-hour dialysis. 5 In order to see if hemodialysis would result in a greater removal of cystine than other amino acids, as would be expected if a large miscible