Glutamine: a new anticystinuric drug?

A recent report by Miyagi and co-workers [New Engl. J. Med. 301: 196-198, 1979] suggested that glutamine caused a decrease in cystine excretion in 1 patient. We studied 2 patients with cystinuria on 2-4 g glutamine for 24 and 60 days. In these patients glutamine showed no effect on the excretion of cystine in the urine. This is consistent with the report by the Mayo clinic where 5 patients were treated with glutamine without any response.