Influence of bacteriuria on the determination of urinary albumin excretion rate.

Increased urinary albumin excretion rates are associated with increased morbidity and mortality in both diabetic and non-diabetic populations (1—3). In studies of microalbuminuria, it is of crucial importance to exclude other confounding factors that influence urinary albumin excretion. Bacteriuria is considered to be a potential cause of transient increased albuminuria (4, 5). The effect of bacterial growth in vitro has been tested and gross microbiological contamination of urine over a 14 day period at room temperature did not consistently affect albumin concentration (6). However, the impact of in vivo bacterial-contamination remains to be elucidated. It is remarkable that patients with bacteriuria are generally excluded from studies on microalbuminuria despite a lack of documentation on the subject. Furthermore, the exclusion criteria used in these studies are highly variable. Some authors demand a sterile urine (7). Others accept small numbers of bacteria (e.g. less than 10/1) or an urinary dipstick with a negative test for leukocytes (8). In several studies, the possible influence of urinary tract infection has not been considered. A consensus concerning bacterial growth and urinary albumin excretion would be desirable.