“…It has been claimed (Yatzidis, Oreopoulos, Tsaparas, Voudiclari, Stavroulaki & Zestanakis, 1966;Giovanetti, Biagini & Cioni, 1968a) that this substance is present in the serum of uraemic subjects in much higher concentrations than in normal subjects. Methylguanidine is known to have high acute toxicity (Mason, Resnik, Minot, Rainey, Pilcher & Harrison, 1937) and its chronic subcutaneous administration to normal dogs in amounts sufficient to produce methylguanidine concentrations similar to those reported in humans with severe renal failure (Yatzidis et al, 1966;Giovanetti et al, 1968a), induces a hypercatabolic state, impaired erythrocyte production and haemolysis, a decrease in platelet count, neuropathy, anorexia, vomiting, diarrhoea, gastrointestinal ulceration and haemorrhages, pulmonary oedema, tachycardia and arrhythmias (Giovanetti, Biagini, Balestri, Navalesi, Giagnoni, de Matteis, Ferro-Milone & Perfetti, 1969) (Balestri, Biagini, Rindi & Giovanetti, 1970). In such concentrations methylguanidine in vitro produces as much haemolysis as is produced by creatinine in concentrations typical of severe renal failure (Giovanetti, Cioni, Balestri & Biagini, 1968b).…”