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.


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.


CONCLUSIONS
The renal functional reserve was present even among progressive RN patients with a glomerular size ranging between +2SD and +4SD.
Matsuoka
Hirofumi
H
Department of Urology, Fukuoka University Faculty of Medicine, Fukuoka, Japan. hmatsu57@fukuoka-u.ac.jp
Nakashima
Yuichi
Y
Oshima
Kazuhiro
K
Tanaka
Masatoshi
M
D000293:Adolescent; D000328:Adult; D002648:Child; D004298:Dopamine / Q000008:administration & dosage; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D007674:Kidney Diseases / Q000473:pathology / Q000503:physiopathology*; D007678:Kidney Glomerulus / Q000473:pathology*; D008297:Male; D012079:Renal Circulation; D014718:Vesico-Ureteral Reflux / Q000473:pathology / Q000503:physiopathology*
D004298:Dopamine