Factors influencing the progression of renal damage in patients with unilateral renal agenesis and remnant kidney

Background. Although some studies have shown that the risk to develop proteinuria and renal insufficiency is increased in patients with a remnant kidney (RK) or unilateral renal agenesis (URA), other patients maintain normal renal function and negative proteinuria, and the reasons to explain these different outcomes are not known. Methods. We performed a retrospective study of 54 patients with a severe reduction in renal mass (33 patients with URA and 21 with RK). Follow-up was 100 +/- 72 months. Results. Twenty patients (group 1) showed normal renal function at presentation, whereas the 34 remaining (group 2) had proteinuria, and some of them renal insufficiency. Group 2 patients were older and had a higher blood pressure and BMI than group 1 patients. Eleven patients of group 1 remained normal throughout follow-up (group 1A), whereas the remaining 9 developed proteinuria/renal insufficiency (group 1B). BMI at presentation was significantly higher in group 1B: 27 +/- 3.6 kg/m(2) versus 21.6 +/- 2.6 kg/m(2), and BMI was the only factor statistically associated with the risk to develop proteinuria/renal insufficiency in group 1. Among group 2 patients, renal function remained stable in 20 (group 2A), and deteriorated (> 50% increase of baseline serum creatinine) in the remaining 14 patients (group 2B). BMI at presentation and treatment with ACEI during follow-up were the only factors statistically associated with the risk for renal failure progression among group 2 patients. Conclusion. Overweight plays a fundamental role in the appearance of proteinuria and renal damage in patients with severe renal mass reduction.