A new method for evaluating an increased general capillary permeability in patients.

The difference between total plasma volume determined with a substance which escapes from vascular beds in the presence of an increase of general capillary permeability and that determined with a substance which is confined to blood even in the presence of an increased capillary permeability may reflect the degree of an increase of general capillary permeability. The total plasma volume was determined by simultaneous injections of 131I-HSA and 51Cr tagged red cells. The capillary permeability was evaluated by calculating the difference (deltaTPV) between total plasma volume determined with 131I-HSA and that determined with 51Cr tagged red cell. deltaTPV in patients with systemic lupus erythematosus, idiopathic thrombocytopenic purpura, chronic active hepatitis, liver cirrhosis and subacute baterial endocarditis was larger than that of controls, averaging 204ml/m2, 178 ml/m2, 82 ml/m2, 131 ml/m2 and 179 ml/m2, respectively. The increase of deltaTPV was considered to indicate the increase of capillary permeability in these patients. A permeability increasing factor was present in serum of patients with an elevated deltaTPV. There was a significant correlation between deltaTPV and the titer of serum capillary permeability increasing factor in these patients.