The quantity of proteinuria is believed to play an important role in
determining the prognosis in various kidney diseases. We investigated the relationship
between urinary protein excretion and renal histological severity in patients with overt
diabetic nephropathy. A total of 60 patients (male 38, female 22, mean age 58 years old)
with type 2 diabetes and overt proteinuria greater than 0.5 g/day and no other renal
disease on renal biopsy were divided evenly into the following 3 groups: group L with
proteinuria of 0.5～1.5 g/day; group M with proteinuria of 1.6～4.0 g/day; and group H
with proteinuria of 4.1～26.4 g/day. Renal histological severity was evaluated
numerically and patients were classified into the following groups: glomerular diffuse
lesions (D) and nodular lesions (N) were divided into 5 stages; vascular lesions (V) and
tubulointerstitial lesions (T) were divided into 4 stages; total histological injury score
was calculated using the total score of the above 4 lesions. We investigated the clinical
profiles of the 9 patients who could be observed from the time of renal biopsy to
induction of hemodialysis. The grades of D and T lesions were significantly higher in
group H than in group L. The grades of N lesions were significantly higher in groups M
and H than in group L. There was no difference in the severity of V lesions between
groups L, M, and H. Total histological injury score was significantly higher in groups M
and H than in group L. The interval from renal biopsy to induction of hemodialysis was
38±19 months; serum creatinine concentration was 7.6±1.6 mg/dl at the time of
induction of hemodialysis. There was a significant correlation between urinary protein
excretion at the time of renal biopsy and declining rate of GFR (r=0.606, p＜0.05). In
conclusion, the quantity of proteinuria was related to renal histological severity and
prognosis of diabetic nephropathy
