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.