Glomerular volume and clinicopathologic features related to disease severity in renal biopsies of African Americans and whites in the southeastern United States.

CONTEXT African Americans have a 4-fold greater risk than whites for developing end-stage renal disease. Glomerulomegaly, possibly related to obesity, has been identified in high-risk populations and is suggested to be a marker for end-stage renal disease risk. OBJECTIVE To investigate differences in glomerular size and patient clinical characteristics at the time of renal biopsy for the major diseases contributing to end-stage renal disease. DESIGN Mean glomerular tuft volumes were estimated by the Weibel-Gomez method (1964) in native renal biopsies of 203 African American and 100 white patients 18 years of age and older by point counting on a stereologic grid. Glomerulosclerosis was graded on individual glomeruli from 0 to 4, and a glomerular sclerosis index was calculated for each biopsy. Relationships between the mean volume of nonsclerotic glomeruli, age, sex, race, sclerosis index, cortical fibrosis, estimated glomerular filtration rate, body mass index, and disease diagnosis were analyzed. RESULTS Racial differences in mean volume of nonsclerotic glomeruli and body mass index were not significant in any disease category, and African Americans had more severe disease as determined by sclerosis index, cortical fibrosis, and estimated glomerular filtration rate only in focal segmental glomerulosclerosis. For all patients, increased sclerosis index and cortical fibrosis and lower estimated glomerular filtration rate were best predicted by increased age (P < .001). CONCLUSIONS For approximately the same severity of disease, African Americans were 10 years or more younger than whites with the difference being seen in all disease categories except membranous glomerulonephritis and diabetes. Glomerulomegaly relative to whites was not a distinguishing feature of African American renal biopsies.