Albuminuria and the permselective properties of the glomerulus in cardiac failure

Fractional dextran clearances (theta D) were used to ascertain whether the albuminuria accompanying cardiac failure (CF) has a hemodynamic basis. In 17 patients with grade-IV CF in whom GFR and effective renal plasma flow (ERPF) were depressed to 58 +/- 7 and 215 +/- 20 ml/min/1.73 m2, respectively, theta D was elevated relative to normal control subjects over the Stokes-Einstein radius (r) interval of 28 to 46 Angstrom. For dextran of equivalent size to albumin (r = 36 Angstrom), the rate of urinary excretion (UD36V) was not increased because elevated theta D36 was offset by the depressed GFR. In contrast, urinary albumin excretion (UalbV) was increased to 82 +/- 35 microgram/min. Thus, for albuminuria in CF to have the hemodynamic basis suggested by elevation of theta D requires that (I) the fractional clearance for anionic albumin be disproportionately enhanced relative to uncharged dextran by reduced glomerular plasma flow and/or (2) that glomerular electrostatic barrier function be impaired in CF. In seven patients with minimal change nephropathy, UD36V was similar to that in CF, but UalbV was 40 times greater than that in CF. Thus, if glomerular electrostatic barrier function is impaired in CF, such dysfunction is trivial by comparison with minimal change nephropathy.