Significance of the renal functional reserve in reflux nephropathy: an evaluation according to the degree of glomerular damage.

OBJECTIVE

In the treatment of progressive reflux nephropathy (RN), the therapeutic benefit and prognosis of the renal function in RN patients appears to be influenced by the degree of renal functional reserve. We designed this study to determine the presence and characteristics of the renal functional reserve in RN patients.

MATERIALS AND METHODS

In the 35 RN patients with renal scars (19 males; mean age 16.1 years), an exogenous renal clearance test was performed to measure the glomerular filtration rate (GFR) and the effective renal plasma flow (ERPF). In the second half of this test, the renal functional reserve was estimated by measuring the GFR and ERPF during low-dose dopamine infusion. These measurements were then compared with the glomerular size, which had been previously determined by a renal biopsy.

RESULTS

Among the patients with a normal glomerular size (-2SD to +2SD), the GFR markedly increased after low-dose dopamine infusion (from 112.15 +/- 52.51 to 182.07 +/- 69.95 mL/min, p < 0.0001), whereas an increase in ERPF was not significant. Among the patients with an enlarged glomerular size (+2SD to +4SD), the GFR and ERPF increased significantly over the baseline values (from 54.60 +/- 32.90 to 114.00 +/- 65.48 mL/min, p = 0.0076; from 281.01 +/- 152.54 to 622.43 +/- 392.73 mL/min, p = 0.0155, respectively). Among the patients with an extremely enlarged glomerular size (>+4SD), both the GFR and ERPF remained almost completely unchanged.

CONCLUSION

The renal functional reserve was present even among progressive RN patients with a glomerular size ranging between +2SD and +4SD.