Urinary beta 2-microglobulin, antimicrobial chemotherapy and infectious diseases

A review of the literature concerning beta 2-microglobulinuria during treatment with antibiotics and during febrile conditions is presented. Aminoglycoside treatment in normally used therapeutic doses causes an impairment of the tubular reabsorptive capacity as evidenced by beta 2-microglobulinuria in the majority of patients. Increases in urinary beta 2-microglobulin can, however, not be used to predict clinical nephrotoxicity in the individual patient since the urinary concentration is dependent on several factors. The main indication for measuring urinary concentrations of this protein during aminoglycoside treatment is to compare the nephrotoxic potential of different aminoglycosides and possibly of other antimicrobial agents, e.g. cephalosporins. Fever causes a temporary impairment of the proximal tubular reabsorptive capacity with increases in the urine of several low molecular weight proteins, e.g. beta 2-microglobulin. It is therefore highly likely that this is the explanation of the beta 2-microglobulinuria seen in patients with pyelonephritis. The suggestion that measurements of urinary beta 2-microglobulin could be of value to determine renal involvement of urinary tract infections is therefore doubtful.