Structural-functional correlations in renal disease. Part II: The Correlations

The relationship between functional abnormalities and structural changes in disease has been the focal point of pathological investigation since the eighteenth century. However, the simultaneous study of these two complementary facets in human disease required proper methods, now available in the excellent and discriminating renal function tests and the percutaneous renal biopsy. Although the functional tests have provided numerical data for analysis, the standard disease descriptions and classifications have not provided an assay in terms suitable for quantitative comparisons. In Part I of this paper, we have presented a method of recording observations defined in relation to the anatomic parts of the kidney and some elementary pathologic processes affecting these parts. The observations included first order estimates of severity and extent of the changes. In developing this schema the aim was to avoid, as far as possible, any a priori judgment of the kind of renal disease in conventional terms or its etiology. Given this anatomic assay, one could then proceed to compare the morbid structure with the morbid function. This communication presents the data on 70 patients in whom the biopsy material was evaluated as described in regard to changes in glomerular, tubular, vascular and interstitial compartments. This information was compared with the simultaneously measured glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and concentrating and acidifying capacities. The results indicated some clear, if unanticipated, relationships. The most interesting and perhaps unexpected finding was that regardless of the basic disease in the kidney, impaired renal function was most closely related to changes in the tubules and in the interstitium.