[Clinicopathological study on progressive hereditary nephritis: observations of ultrastructural lesions in the glomerular basement membrane].

Four boys and six girls with progressive hereditary nephritis were studied clinicopathologically. Renal biopsy was performed 16 times in ten cases. Mean age at renal biopsy was 7.3 years old (range 2 to 14 years old). The obtained results were as follows: (1) Montages of electron micrographs were prepared to complete one whole glomerulus. The length of the glomerular basement membrane (GBM) with the characteristic splitting of the lamina densa (Reticulation) was measured and expressed as a percentage of the total length of the GBM. The range of the percentage of the GBM with Reticulation was from 2 to 43% (13.4 +/- 10.0%, mean +/- SD, n = 16). In 4 cases of the 5 cases performed serial renal biopsy, the percentage of the GBM with Reticulation at the 2nd biopsy increased compared with the 1st one. (2) Protein excretion in the urine, serum albumin, alpha 2-globulin, fibrinogen and total cholesterol showed the correlation with the percentage of the GBM with Reticulation. (3) Incomplete ruptures (deep invasion of the epithelial cells into the thickened GBM with Reticulation) were observed. Those suggested that the GBM became fragile associated with the expansion of Reticulation and finally ruptured. Gaps of the GBM were observed 0 to 3 per in one glomerulus (0 to 1.87 per 1mm GBM) and the serial biopsies showed an increase in the number of the gaps as time passed. (4) This study showed the increase in factors activating the blood coagulation such as total cholesterol and fibrinogen, with the expansion of the GBM with Reticulation. And in a nephrotic case, fibrin strands were observed in the glomerular capillary loops and in the GBM. These findings suggest that the activation of the blood coagulation plays a role for the damage of the glomeruli in progressive hereditary nephritis.