Sulphate Space in the Human Organism after Intravenous Administration of Radiosulphate (Na235SO4)

Abstract

The value of determining the extracellular volume in human beings by means of sulphate labeled with ³⁵S has been investigated. Attempts have been made to find the correct equilibration time after an injection of the tracer substance in 25 normal persons and 14 patients with various diseases. Possible sources of error have been explored. The method is reliable in normal persons, if corrections for the loss of ³⁵S in the urine during the equilibration period are made. In normals the equilibration period was found to be 60 to 90 minutes. In patients with ascites an equilibration was seldom obtained even 180 minutes after the injection of the tracer. As the average urinary loss during 3 hours was 37 per cent of the injected dose, and as the sulphate slowly penetrates the cells and is incorporated in the mucopolysaccharides, it is concluded that ³⁵S-labeled sulphate is unsuitable for determinations of the extracellular volume in a large group of patients in whom this parameter would be of great clinical value.