Glomerular Diameter Measurements on Light Microscopy: A New Parameter Available to Pathologists and its Utility in IgA Nephropathy

Background: With the availability of whole slide digital scanners, fairly accurate glomerular diameter (GD) measurements are now possible on light microscopy. The value of these measurements in prognosis and diagnosis of immunoglobulin A nephropathy (IgAN) have not been studied widely. IgAN is a major cause of end-stage renal disease (ESRD) worldwide, and its progression is currently assessed using Oxford scores, serum creatinine, and 24-h urinary protein. We aimed to correlate the mean and maximum GDs with serum creatinine, 24-h urinary protein, and Oxford scores in patients with IgAN.

Materials and methods: One hundred biopsies of IgAN with a minimum of eight viable glomeruli were collected along with data of their 24-h proteinuria, serum creatinine, and Oxford scores. The slides were scanned using the Philips IntelliSite Pathology Solution-Ultra Fast Scanner. Mean GD of each glomerulus was calculated as the mean of two measurements, that is, the maximal diameter of the glomerulus and the maximal chord perpendicular to the maximal diameter. Maximum GD was also recorded for each case. The Spearman rho/Pearson R correlation coefficient was used to make this correlation. P-values <0.05 were considered statistically significant.

Results: The mean age of the patients was 34.67 ± 12.03 years, and they showed a male preponderance. The overall mean GD was 151.82 ± 28.69 µm, and maximum GD was 205.40 ± 32.76 µm. No statistically significant correlation was observed between the mean or maximum GD and the 24-h proteinuria, serum creatinine levels, and Oxford scores.

Conclusion: GD in IgAN does not correlate with proteinuria, serum creatinine, or Oxford scores.