Epithelial foot-process effacement in patients with proteinuria.

In an effort to determine the pattern of foot-process effacement or "fusion" in proteinuria, quantitative measurements were performed on human tissue from patients with urinary protein excretion exceeding 0.5 g/d. Serial electronmicrographs were analyzed and the results related to both quantitative urinary protein and underlying disease. Although foot-process effacement was widespread, it was never universal. Some portions of glomeruli were morphologically normal in every case. The proportion of effaced foot processes did not vary directly with the level of urinary protein. With the possible exception of focal glomerulosclerosis, the primary disease did not appear to influence the amount of effacement.