Value of antistreptolysin "O" titers for differential diagnosis of renal diseases.

A.S.O. titers were determined in 93 children with various kidney diseases. In addition, 52 children without renal disorders were investigated as controls. In the children with renal disease, 38 suffered from the "idiopathic", "primary" nephrotic syndrome of childhood. Thirteen had acute, post-infectious glomerulonephritis, 16 had "primary" chronic glomerulonephritis, 3 had pyelonephritis, and 1 had disseminated lupus nephritis. In acute glomerulonephritis, with or without N.S., the titers were higher than in the controls, which is known and consistent with the frequency of preceding streptococcal infections. Children with chronic glomerulonephritis, with and without associated N.S., did not show a similar tendency to increased values. All patients but one with "primary", , "idiopathic" N.S. of childhood had titers of less than 100. They were between 50 and 12 Todd units. These titers were observed early during the course of the disease and persisted for years in spite of remissions. They were not related to concomitant antimicrobial therapy, nor to corticosteroid administration. In "idiopathic" nephrotic syndrome of childhood a titer of less than 100 does not, in itself, lead to the diagnosis of a N.S. of childhood. However, a greater than 100 titer speaks against it and may well serve as a valid indication for a renal biopsy, in order to differentiate this disease from acute glomerulonephritis, and also from R.P.G.N. whenever they are associated with a N.S. The low titers are only of value in differentiating the "primary" form of the N.S. from the "secondary" forms which are preceded by chronic renal disease or which are due to another underlying, systemic disease. In nephrotic children less than 6 years of age, the less than 100 A.S.O. titers may also be due to their age.