An alternative pathway of L-arginine metabolism leading to the formation of guanidinosuccinic acid. The accumulation of urea in uremic plasma exerts an inhibitory effect on the enzymes of the urea cycle. This activates alternative metabolic pathways such as the transamidination of arginine leading to guanidinosuccinic acid formation.27 It has been proposed that guanidinosuccinic acid can also be formed by enzymatic cleavage of argininesuccinate, another product of the urea cycle.