Radiosulphate: its metabolism and use in measurement of extracellular fluid volume in calves

Radiosulphate injected intravenously into calves under 14 days of age equilibrated, by 30 min, with a mean fluid volume of 311 ml/kg body weight. During the equilibration period 3.7 per cent of the injected dose was excreted in the urine. The volume of distribution of radiosulphate increased for at least 4.5 h after equilibration suggesting that it penetrated beyond the readily miscible water of the extracellular fluid.