Background: Large glomeruli are a common finding in the early stages of progressive renal disease. We studied the relationship between glomerular surface area (GSA) and clinicopathologic features of IgA nephropathy (IgAN), including renal outcome, to better understand the role of GSA in IgAN.
Methods: We analyzed renal biopsy specimens and clinical information from 34 patients with IgAN. Mean and maximal GSA were determined using a computed imaging analyzer.
Results: Mean GSA was 16,811 ± 4,671 μ2 in IgAN patients (n = 34). When we analyzed various clinical parameters of IgAN patients, there were significant correlations between mean or maximal GSA and age, body mass index (BMI), systolic and diastolic blood pressure, estimated glomerular filtration rate (eGFR), and pathologic findings including H.S. Lee' grades, interstitial fibrosis, and tubular atrophy. GSA did not show any relationship with the degree of hematuria and proteinuria. By multivariate regression analysis of age, BMI, blood pressure, H.S. Lee' grades, and eGFR as independent variables, mean GSA was associated with H.S Lee' grades and initial eGFR. The results for maximal GSA were the same as those for mean GSA. When we divided IgAN patients according to their mean levels of GSA, the group with larger GSA had higher blood pressure and H.S. Lee' grades and lower initial and final eGFR. More patients in the larger GSA group showed the decline in eGFR of more than 15 ml/min/1.73 m2 during the followup period compared with the smaller group.
Conclusion: These results suggest that glomerular size, estimated by measuring GSA, is related to pathologic findings and renal function in IgAN. However, further investigation is required to determine if GSA can be used as a prognostic indicator of IgAN.