Albumin excretion by the kidney: the effects of volume expansion

With the use of a highly sensitive radioimmunoassay for rat albumin, urine albumin excretion rate (UalbV) was measured under baseline conditions and following saline-induced volume expansion. Volume expansion was associated with a significant increase in glomerular filtration rate (GFR), urine volume (V), fractional excretion of sodium (FEna), and UalbV (p less than 0.002). The increase in UalbV correlated far better with the increase in GFR than the increase in F and FEna, which suggests that volume expansion results in an increased albumin filtration with saturation of the tubular reabsorptive capacity.