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

Abstract

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 (n = 100): subjects without RUTI, GB (n = 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.

Keywords: NAG; NGAL; RUTI; TFG-beta 1; elderly; glomerular filtration.

Figure 4.

Figure 1.

Most important variables in the clusters of the general group. GFR, glomerular filtration rate; NAG, N-acetyl glucosaminidase; NGAL, neutrophil gelatinase-associated lipocalin; Pr Urine, proteins in urine.

Figure 2.

Most important variables in the clusters of GA. GA, group A; GFR, glomerular filtration rate; NAG, N-acetyl glucosaminidase; NGAL, neutrophil gelatinase-associated lipocalin.

Figure 3.

Most important variables in the clusters of GB. GB, group B; GFR, glomerular filtration rate; NAG, N-acetyl glucosaminidase; NGAL, neutrophil gelatinase-associated lipocalin; Pr Urine, proteins in urine.