Urinary excretion of beta-2-microglobulin in patients with active metabolic stone disease.

The aim of the present work is to evaluate the function of the proximal tubule in patients with active metabolic stone disease (a.m.s.d.), recognizing the urinary excretion of beta-2-microglobulin (B2-M) as a sensitive marker of that function. The investigated group included 30 patients with a.m.s.d. accompanied by chronic pyelonephritis (CP) and 31 patients with a.m.s.d. without CP. The serum and urinary B2-M concentrations were estimated by radioimmunoassay. The clearance of B2-M (CB2-M) and the tubular reabsorption of B2-M (TRB2-M) were estimated. Patients with a.m.s.d. and CP showed an increased excretion of B2-M, significantly higher values of CB2-M and a significantly lower TRB2-M. The results indicate that the proximal tubular dysfunction in the group of patients with a.m.s.d. is a result of a chronic inflammatory process in the urinary tract.