Measurement of Glomerular Area in Primary Glomerular Diseases With a Digital Pathology Software

Objective: Kidney biopsy is essential to evaluate the activity of underlying kidney disease and the risk factors related to kidney disease progression. Glomerular morphometry is a simple but uncommonly used qualitative predictor of long-term kidney function. But it is mysterious if glomerular morphometry changes due to underlying glomerulonephritis. Measurement quantification is also necessary for reliable interpretation. We aimed to evaluate glomerular morphometry with glomerular area measurements quantitatively with digitally scanned slides in the primary glomerular diseases. Methods: We retrospectively analyzed 198 patients with nephrotic syndrome that underwent kidney biopsy between 2017 and 2019. 48 patients enrolled into the study after the exclusion criteria. We measured the glomerular area as maximum, minimum, and mean areas, using image analysis software. Results: Forty-eight kidney biopsies were analyzed retrospectively under three primary glomerular disease groups as IgA nephropathy (37.5%), focal segmental glomerulosclerosis (29.2%), and membranous glomerulonephritis (33.3%). The glomerular area measured as maximum, minimum, and mean, were similar between 3 groups. The maximum glomerular area was negatively correlated with serum albumin and positively correlated with 24hr proteinuria (r= - 0.592, p=0.044, and r=0.531, p=0.022) at the time of diagnosis. At the end of one year, maximum glomerular area was positively correlated with serum creatinine (r=0.385, p=0.019) and negatively correlated with eGFR (r= - 0.493, p=0.043). Conclusions: At the time of diagnosis of glomerular diseases, maximum glomerular area measurement during the pathological assessment might be an additional marker to estimate the ultrastructure of the kidney and the clinical course of the disease.