Structural-Functional Relationships in Renal Amyloidosis

ABSTRACT

The pathogenetic mechanism of renal dysfunction in renal amyloidosis is poorly understood. To evaluate the morphologic parameters which are correlated with renal function in this disorder, we have examined renal biopsies from 14 patients with renal amyloidosis by morphometry. Of the 14 patients, 8 were male and 6 were female. They were between 41 and 70 years of age. The serum concentration of albumin and creatinine were 2.1+/-0.7 mg/dl and 1.1+/-0.5 mg/dl, respectively. The 24-hour excretion of urinary protein was 7.9+/-5.2 g. Creatinine clearance was 62+/-23 ml/min/1.73m2. The mean glomerular volume (MGV) was (2.2+/-1.3) 10(6) micrometer3. The surface density of peripheral glomerular basement membrane [Sv (PGBM/glom)] was 0.049+/-0.027 (micrometer3/micrometer3). Volume density of mesangium [Vv (mes/glom)] was 0.31+/-0.14 (micrometer3/micrometer3) and volume density of glomerular amyloid deposition [Vv (amyl/glom)] was 0.21+/-0.14 (micrometer3/micrometer3). The volume density of cortical interstitium [Vv (int/cortex)] was 0.14+/-0.09 (micrometer3/micrometer3). The serum creatinine concentration was significantly correlated with Vv (int/cortex) (r=+0.66, p<0.05). MGV was correlated with Vv (mes/glom) (r=+0.75, p<0.01) and Vv (amyl/glom) (r= +0.68, p<0.05) but showed negative correlation with Sv (PGBM/glom) (r=-0.79, p<0.01). Sv (PGBM/glom) showed negative correlation with Vv (mes/glom) (r=-0.77, p<0.01) and with Vv (amyl/glom) (r=-0.87, p<0.01). Positive correlation was observed between Vv (mes/glom) and Vv (amyl/glom) (r=+0.95, p<0.01). These results suggest that the decreased renal function in patients with amyloidosis is related to interstitial fibrosis rather than glomerular lesions. In addition, glomerular hypertrophy in these patients is related to amyloid deposition in the mesangium and peripheral glomerular basement membrane.