R. Coppo et al., GLOMERULAR PERMSELECTIVITY TO MACROMOLECULES IN REFLUX NEPHROPATHY - MICROALBUMINURIA DURING ACUTE HYPERFILTRATION DUE TO AMINO-ACID INFUSION, Clinical nephrology, 40(6), 1993, pp. 299-307
Reflux nephropathy is an important cause of chronic renal failure in c
hildren. After the parenchymal scar, the progression is thought to be
mediated by glomerular hypertension in remnant nephrons resulting in m
odifications in permselectivity to macromolecules. Proteinuria correla
tes with a progressive course. The glomerular permselectivity to macro
molecules in basal conditions and after acute hemodynamic stress was i
nvestigated in 28 children whose bilateral vesico-ureteric reflux (VUR
) had been previously surgically corrected (meanly 5.6 years before) a
nd with normal creatinine clearance (CrCl). Bilateral renal scarring (
0 to 8 scale for both kidneys) was 4.3 +/- 1.6. Albuminuria (UAE) was
evaluated in basal conditions and under acute hyperfiltration induced
by amino acid (Aa) infusion. After isotonic saline at 310 ml/hour/1.73
m2, 6 mg/kg/min of Aa were infused for 2 hrs. UAE was significantly h
igher than controls in basal conditions (p <0.01), and further increas
ed after Aa infusion (p <0.02). Microalbuminuria was detectable in 53.
5% of the children in basal conditions and in 64.3% after Aa. Also uri
nary beta2 Microglobulin significantly increased at the end of the tes
t (p <0.001). CrCl significantly increased at the first hour (p <0.05)
. Children with severe renal parenchymal scarring had greater UAE (p <
0.01) and beta2M (P <0.02) values after provocative test than those wi
th mild renal damage. In 8 children GFR and ERPF were measured by mean
s of inulin and p-hippurate clearance respectively. The variations in
UAE during Aa infusion were significantly correlated with GFR dynamics
(p <0.05) while they were not in fluenced by ERPF modifications. In c
hildren with initial RN and still normal CrCl a provocative test of hy
perfiltration with Aa infusion induces a significant modification in p
ermselectivity to macromolecules evidenced by microalbuminuria.