Demonstration of the presence of digoxin-like immunoreactive substance (DLIS) in the serum and urine in children with nephrotic syndrome.

Longitudinal changes of digoxin-like immunoreactive substance (DLIS) in serum and urine from nephrotic children have been studied. The magnitude of DLIS in samples was measured by digoxin RIA kit. The binding activity to the ouabain receptor was measured by radioreceptor assay using crude rat brain synaptosomal fraction. In five cases of nephrosis, the mean value of DLIS in diuresis was significantly higher than during other stages (p less than 0.05). It was also higher than the levels recorded for six patients with nephritis (p less than 0.05). The presence of DLIS in the urine followed a similar pattern. The positive correlation between urine DLIS and ouabain-like substance (OLS) corrected by creatinine was observed for one month after the onset of nephrosis. The present study indicates the presence of DLIS in the serum and urine from patients with nephrosis which have the binding activity to the ouabain receptor. DLIS may be involved in natriuresis and may regulate active sodium transport in nephrotic children.