Urinary Excretion of β ₂ Microglobulin after the Induction of a Diuresis

An increased diuresis was induced in each of four healthy subjects by intravenous infusion of urea, saline and sodium bicarbonate and by an oral water load. The excretion of a low molecular weight protein (LMW-protein), beta2-Microglobulin (beta2mu), was determined by a radioimmunoassay, the urinary concentrations of the protein being in the range 0.007-0,3 mug/ml. The hourly excretion of beta2 mu was not significantly influenced by varying loads of water, sodium, and osmoles which suggests that the tub ular reabsorption of LMW-proteins is stable under these conditions and that even a moderately increased excretion of such proteins may reflect a distrubed proximal tubular function.