Spectrum and Distribution of Biopsy-proven Kidney Diseases: A 12-year Survey of a Single Center in Iran

Data about the prevalence of biopsy-proven kidney diseases in Iran are rare, and none of the previous studies used electron microscopy for diagnosis. This study aimed to analyze the prevalence of biopsy-proven kidney diseases in Iran's primary referral center. To the best of our knowledge, this is the most extensive study carried out in Iran. Reports of kidney biopsy samples from patients referred to our center in 2007-2018 were reviewed for demographic data, clinical presentation, and final diagnosis. Statistical analyses were performed. Among the 3455 samples received, 2975 were analyzed. Nephrotic syndrome (39%) was the most common cause of biopsy, followed by subnephrotic proteinuria (18%), hematuria in association with proteinuria (15%), renal failure (9%), isolated hematuria (6%), and lupus nephritis (LN) (4%). The most common diagnoses were membranous glomerulonephritis (17.9%), focal segmental glomerulosclerosis (FSGS) (15.9%), LN (13.7%), minimal histopathological findings (unsampled FSGS vs. minimal change disease, 12.1%), Immunoglobin A nephropathy (IgAN) (6.5%) and Alport syndrome (6.1%). NS and proteinuria were the most common indications for a kidney biopsy. IgAN and LN were the most common causes of primary and secondary glomerulonephritis, presenting with hematuria and proteinuria, respectively. Although membranous glomerulonephritis was the most common disease, it has been replaced by FSGS in recent years.