Could asymptomatic cystinuric siblings have malabsorption of amino acids?
Dr Lisa Ruml answers: While it is true that most cystinuric patients are unable to absorb some amino acids (cystine, lysine, arginine, and ornithine), there is not a problem with protein malnutrition. Amino acids are also absorbed in pairs, and cystinuric patients can absorb these amino acids when they are in the pair form or short chains. Thus, there is not a problem with protein deficiency and amino acid supplements are not necessary. There is also no good evidence that mental retardation is in any way associated with cystinuria; and the observation that cystinuric patients are shorter than the general population has not been substantiated.
