Organ-Specific Monitoring of Solitary Kidney after Living Donation by Using Markers of Glomerular Filtration Rate and Urinary Proteins.

BACKGROUND: Effective follow-up after living kidney donation is important for maintaining the renal function of the donor. We investigated whether the estimated glomerular filtration rate (eGFR) and urinary protein and enzyme levels can provide important information regarding the state of the remaining kidney after donor nephrectomy. METHODS: Seventy-five living donations were included (prospective/retrospective) in the study. The following parameters were measured up to 1 year after donor nephrectomy: serum creatinine and cystatin C as markers of the GFR; the high-molecular-weight urinary proteins as markers of glomerular injury; and the low-molecular-weight urinary proteins and urinary enzymes as markers of tubular function. RESULTS: One year after kidney donation, the creatinine and cystatin C values were 1.38-fold increased than their initial values, while the eGFR was 32% lower. At that time, 38% of donors had a moderate or high risk of CKD progression. The biochemical urinary glomerular and tubular kidney markers examined showed different behaviors. After a transient increase, the glomerular proteins normalized. Conversely, the detection of low-molecular-weight urinary proteins and enzymes reflected mild tubular damage at the end of the study period. CONCLUSIONS: Our findings suggest that for the evaluation of mild tubular damage, low-molecular-weight marker proteins should be included in the urine diagnostic of a personalized living kidney donor follow-up.

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.