Increased urinary markers of kidney damage in the institutionalized frail elderly due to recurrent urinary tract infections.

OBJECTIVE

To characterize the impact on kidney injury of recurrent urinary tract infections (RUTI) in the frail elderly.

METHODS

Prospective observational study in 200 frail elderly subjects for 1 year. Groups: GA ( = 100): subjects without RUTI, GB ( = 100): subjects with RUTI. Variables: age, concomitant diseases, glomerular filtration rate (GFR), urine neutrophil gelatinase-associated lipocalin (NGAL) at the beginning (NGAL-1) and end (NGAL-2) of the study, urine N-acetyl glucosaminidase (NAG) at the beginning (NAG-1) and the end (NAG-2) of the study, urine transforming growth factor-beta 1 (TGFβ-1). Descriptive statistics, Mann-Whitney test, Chi-squared test, Fisher's exact test, and multivariate analysis were used.

RESULTS

Mean age was 84.33 (65-99) years old, with no difference between GA and GB. Mean NGAL-1 was 1.29 ng/ml (0.04-8). There was lower in GA than in GB. Mean NGAL-2 was 1.41 ng/ml (0.02-9.22). NGAL-2 was lower in GA than in GB. Mean NAG-1 was 0.38 UU.II/ml (0.01-2.63. NAG-1 in GA was lower than in GB. Mean NAG-2 was 0.44 UU.II/ml (0-3.41). NAG-2 was lower in GA compared with GB. Mean TGFβ-1 was 23.43 pg/ml (0.02-103.76). TGFβ-1 was lower in GA than GB. There were no differences in the presence of secondary diagnoses between GA and GB. NAG-2 and NGAL-1 were the most determining factors of renal function; in GA it was NGAL-2, followed by NAG-1; in GB it was NGAL-1, followed by NAG-2.

CONCLUSION

Frail elderly with RUTI have higher urinary levels of renal injury markers, specifically NGAL, NAG, and TGFβ-1, chronically in periods between urinary tract infection (UTI). Urinary markers of renal injury, specifically NGAL, NAG, and TGFβ-1, identify early deterioration of renal function, compared with serum creatinine, or albuminuria, in frail elderly with recurrent urinary infections.