Evaluation of a procedure for systematic semiquantitative analysis of glomerular ultrastructure in human renal biopsies.

A method is described for systematic semiquantitative investigation of glomerular ultrastructure in renal biopsies from patients with glomerulonephritis. Three glomeruli per biopsy were studied by electron microscopy. Ten systematically recorded micrographs at x12,000 and a montage covering the whole glomerular cross-section at x3,000 were analyzed from each glomerulus. The severity of each of 34 different ultrastructural lesions was semiquantitatively evaluated on a 4-degree scale, 0 to +++. The usefulness of the method was evaluated by calculating different parameters for the reproducibility of semiquantitative scoring, representativeness of micrographs, and representativeness of glomeruli. The reliability of the method was considered good or acceptable with respect to 17 of the lesions. Ten lesions obtained a high reproducibility of scoring but the usefulness of the scores was limited due to a segmental and/or focal distribution of these lesions. The evaluation of these lesions can be improved by analyzing a larger number of micrographs, or glomeruli, or both. Seven lesions were so rare in the present biopsies that no statistical evaluation was possible. When applied to a large number of biopsies, this practical and useful method allows a reproducible comparison of the patterns of ultrastructural lesions in various types of glomerulonephritis.