To evaluate the effect of an acute oral protein lend (OPL) on urinary
albumin excretion (UAE) in uninephrectomized subjects with a negative
Albustix test, in relation to the time since nephrectomy. the UAE was
determined by a double-antibody I-125 radioimmunoassay in 3-hour urine
collections before and after 150 g OPL under conditions of moderate
physical activity in 18 subjects who underwent unilateral nephrectomy
more than 10 years (346.5+/-178.60 months) before evaluation and had a
mean basal creatinine clearance (C-Cr) of 45.3+/-14 ml/min (group 1), in
21 subjects who under went unilateral nephrectomy less than 10 years
(31.5+/-28 months) before evaluation and had a mean basal C-Cr of
76.0+/-22 ml/min (group 2), and in 16 normal volunteers (controls) with
a mean basal C-Cr of 103.1+/-12 ml/min. The UAE was higher in group 1 as
compared with either group 2 or controls at both basal state (90.8+/-65,
19.6+/-17, and 11.0+/-5 mu g/min/100 C-Cr for groups 1 and 2 and
controls, respectively; p<0.001) and after OPL (92.0+/-65, 43.6+/-24,
and 12.0+/-5 mu/min/100 C-Cr for groups 1 and 2 and controls,
respectively; p<0.001). However, the increase in UAE following OPL was
significant (p<0.001) only in group 2 patients. In all patients, the
basal UAE was negatively correlated with basal C-Cr (r=0.63; p<0.001)
and positively correlated with the time since nephrectomy (r=0.73;
p<0.001) and with both systolic (r=0.57; p<0.001) and diastolic blood
pressures (r=0.69; p<0.001). Ca calculated using 3-hour urine
collections increased more in controls (11.2+/-44.2%) than in patient
groups 1 (1.6+/-0.89) and 3 (7.7+/-3.7%; p<0.001). Basal C-Cr
calculated using 24-hour urine collections the day before the test was
negatively correlated with the time since nephrectomy in group 1
(r=-0.69; p<0.001) and positively correlated with the time since
nephrectomy in group 2 (r=0.89; p<0.001). Multiple regression analysis
revealed that the relationship between C-Cr and duration of uninephric
state was independent of age or systolic and diastolic blood pressures
in both patient groups. These results suggest that UAE increase
significantly after an OPL in subjects who have been nephrectomized less
than 10 years before the study and have basal C-Cr values higher than
50% of normal. They also suggest that the risk of developing renal
insufficiency increases with time in subjects with a solitary kidney for
more than 10 years; this increase in risk seems to follow a progressive
compensatory increase in glomerular filtration rate of the remnant
kidney during the early years following uninephrectomy
