Albumin elimination in female WAG/Rij rats with age: a longitudinal study

A longitudinal study was performed to examine total albumin elimination and urinary albumin excretion in the female WAG/Rij rat. Complete necropsies were performed following the spontaneous death of the animals. The survival characteristics of this group was similar to that of survival cohorts. An increase in total albumin elimination, urinary protein excretion and urinary albumin excretion was observed with age. A proportional increase in the contribution of albumin to the urinary protein excretion was also observed. However, the observed increase in urinary albumin excretion could not totally account for the increase in total albumin elimination. The predominant kidney lesion was chronic progressive nephrosis. The histological severity of the renal lesions were closely correlated with the increase in urinary albumin and total protein loss. It is concluded that the increase in total albumin elimination in rats in this study was due to age-related changes and not to cohort effects.