Extremely rapid stone formation in cystinuria: look out for dietary supplements!

Abstract

Cystinuria is an autosomal recessive disease characterized by recurrent nephrolithiasis. The prevention of new stones is based on diluting and alkalinizing urine, as well as a low salt and moderate protein intake. The avoidance of food rich in methionine (the precursor of cystine) is also advocated. We report the case of a young adult adherent to the preventative strategy who was stone-free and within months formed a large stone. This coincided with the recent intake of a dietary supplement containing both cystine and methionine. Patients and physicians should be aware of the potential harm of such supplements in patients with cystinuria.