[Usefulness of beta-2-microglobulin determination in the differential diagnosis of infections in the upper and lower parts of the urinary tract].

The purpose of the study was assessment of the usefulness of renal excretion of beta 2-microglobulin (B2M) in the differential diagnosis of infections situated in the upper and lower parts of the urinary tract. The study was carried out in 15 patients with infections of the upper part of the urinary tract (acute pyelonephritis), 10 patients with infections of the lower part of this tract (cystitis), and 50 healthy controls. In all studied subjects the B2M concentration was assessed in the serum and urine by radioimmunoassay (Pharmacia B2-micro RIO 100, Uppsala, Sweden). From the obtained data B2M clearance (CB2M) and tubular reabsorption of B2M (TRB2M) were calculated. In patients with upper urinary tract infections a statistically significantly greater urinary B2M excretion, significantly higher CB2M value, and significantly decreased TRB2M were found as compared to patients with lower urinary tract infections. The obtained data suggest presence of dysfunction of the proximal tubule in upper urinary tract infections and demonstrate the usefulness of beta 2-microglobulinuria assessment in the differential diagnosis of upper and lower urinary tract infections.