Urinary procollagen III aminoterminal propeptide and ß-catenin - New diagnostic biomarkers in solitary functioning kidney?

PURPOSE: We aimed at evaluating urinary levels of procollagen III aminoterminal propeptide (PIIINP) and ß-catenin and the relationship between these markers and clinical and laboratory variables in children with a solitary functioning kidney (SFK). PATIENTS AND METHODS: The study group consisted of 98 (M/F: 62/36) children with an SFK with a median age of 8 years. An age-matched control group contained 54 healthy peers. Urinary levels of procollagen III aminoterminal propeptide and ß-catenin were measured using a commercially available immunoassay kit. RESULTS: The urinary values of PIIINP (UPIIINP) were significantly increased in patients with SFK versus controls (p < 0.01). Our analysis revealed no significant differences in urinary ß-catenin levels between the SFK patients and control subjects (p > 0.05). Only urinary PIIINP levels were correlated to renal function tests, such as serum creatinine, urea, uric acid, and estimated glomerular filtration rate (p<0.05). CONCLUSIONS: An increased urinary level of PIIINP may indicate early kidney impairment in children with SFK. Urinary ß-catenin does not seem to play any important role as a marker of renal function in children with SFK. Further long-term studies are required in order to evaluate the clinical usefulness of these markers and their predictive value of chronic kidney disease (CKD) progression.

Urinary biomarkers in obstructive nephropathy.

BACKGROUND AND OBJECTIVES: Obstructive nephropathy is a leading cause of CKD in children. The assessment of severity of renal impairment and the prediction of which children will progress to renal failure are, however, challenging. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This case-control study measured the urinary excretion of candidate biomarkers in 27 prevalent case-patients with posterior urethral valves (PUVs) and 20 age-matched controls, correlated their urinary concentration with GFR, and analyzed receiver-operating characteristic (ROC) curve and regression analyses to assess their performance as tests for low GFR. RESULTS: The median urinary protein-to-creatinine ratio was higher in children with PUV (45 g/mol; range, 5-361 g/mol) than in controls (7 g/mol; range, 3-43 g/mol) (P<0.01) and correlated inversely with renal function (r = -0.44; P<0.05). In whole urine, excretion of aquaporin-2 was significantly decreased, whereas that of TGFß and L1 cell adhesion molecule (L1CAM) was significantly increased. Whole-urine TGFß excretion correlated inversely with GFR (r = -0.53; P<0.05). As tests for low GFR, whole-urine TGFß, L1CAM, and urinary protein-to-creatinine ratio performed best, with areas under the ROC curves of 0.788, 0.795, and 0.814, respectively. By linear regression analysis, whole-urine TGFß, L1CAM, and urinary protein-to-creatinine ratio were associated with low GFR in the case-patients. CONCLUSIONS: Candidate biomarkers of obstructive nephropathy can be readily measured in whole urine and in urine exosomes. In boys with PUV, these biomarkers correlate with GFR.