Concentrations in serum and urinary excretion of guanidine, 1-methylguanidine, and 1,1-dimethylguanidine in chronic renal failure.

Guanidine (G), 1-methylguanidine (MG), and 1,1dimethylguanidine (DMG) have long been implicated as uremic “toxins.’A method has been developed for determining G, MG, and DMG in serum and urine.Specimens were chromatographed on carboxylateresin,with use of 1 molar NaOH, and quantitated colorimetricallywith a modificationof the VogesProskauer reaction.The mean values for G and MG in the serum of uremic patientswere 0.3 and 0.4 mg per liter,respectively.DMG was not detected. Although the urinary excretion of MG is significantly increased in renal failure,the concentrations of G, MG, and DMG in serum are not markedly increased, and it isthereforeunlikelythatG, MG, or 0MG contribute to the toxic manifestations of the uremic syndrome.