Figure 0001: Correlation between % urinary peptides and urine protein-creatinine ratio

Mentions: As depicted in Table 2, there was a significant decrease in urinary peptides/g creatinine in group I compared to group III (P < 0.01), however, there was no such difference between groups I and II. The percentage of urinary peptides was decreased in both group II and III cases compared to group I (P < 0.01), and there was a significant difference in % urinary peptide content in group II compared to group III (P < 0.01). On correlation, the % urinary peptides correlated negatively with urinary proteins/g creatinine (r = - 0.782, P < 0.01) [Fig. 1] and positively with urinary peptides/g creatinine (r = 0.238, P < 0.01) [Fig. 2]. Urinary protein levels determined by Bradford's method were found to correlate positively with those determined by the clinical chemistry analyzer (pyrogallol red dye binding) method (r = 0.915, P < 0.01).

Prakash M, Shetty JK, Dash S, Barik BK, Sarkar A, Prabhu R - Indian J Nephrol (2008)

Bottom Line: There was a significant decrease in the levels of urinary peptides in group III compared to group I (P < 0.01), however, there was no difference in peptides between groups I and II.The percentage of urinary peptides was decreased in both groups II and III compared to group I (P < 0.01), and there was a significant difference in % urinary peptide content in group II compared to group III (P < 0.01).Our data suggest that there is a marked decrease in urinary peptide levels with an increase in proteinuria.

Affiliation: Department of Biochemistry, Kasturba Medical College, Manipal, Karnataka, India.

Abstract: Although considered useful in the diagnosis and prognosis of renal diseases, proteinuria can only be detected after significant renal paranchymal changes. There is considerable interest in the estimation of urinary peptides as an early marker of renal disease. In the current study, we have estimated urinary peptides in patients with different grades of proteinuria. Twenty-four hour urine samples were collected from 138 subjects and classified into three groups based on the urine protein excreted: group I (normoproteinuria, 0-150 mg/day, n = 37), group II (microproteinuria, 150-300 mg/day, n = 31), and group III (macroproteinuria, > 300 mg/day, n = 70). Urine proteins were determined using Bradford's method and urinary peptide levels were determined by subtracting Bradford's value from the Lowry value of the same sample. There was a significant decrease in the levels of urinary peptides in group III compared to group I (P < 0.01), however, there was no difference in peptides between groups I and II. The percentage of urinary peptides was decreased in both groups II and III compared to group I (P < 0.01), and there was a significant difference in % urinary peptide content in group II compared to group III (P < 0.01). On correlation, % urinary peptides correlated negatively with urinary proteins/g creatinine (r = - 0.782, P < 0.01) and positively with urinary peptides/g creatinine (r = 0.238, P < 0.01). Our data suggest that there is a marked decrease in urinary peptide levels with an increase in proteinuria. This may suggest impaired tubular protein reabsorption and degradation capacity of renal tubules.