Value of “Active” Urine Sediment Examination in Predicting Proliferative Glomerular Pathology on Kidney Biopsy

Background: Urine sediment examination is an important preliminary investigation for the nephrologist and helps him decide whether the patient has a proliferative or non-proliferative glomerular pathology. Recently, there is an increasing trend of using easier, non-specific dipstick method for urine examination leading to a decline in the importance of urine sediment examination. Here, we attempt to define guidelines for bio-chemical and microscopic parameters in order to develop a uniform and clinically relevant reporting system for urine sediment examination. Methods: Urine samples were reported as inactive or active sediment. A tiered system of reporting urine sediments was developed including inactive sediment, Inactive sediment with moderate/significant proteinuria, glomerular hematuria, and active sediment, active sediment with significant proteinuria / features of proliferative activity. The urine sediment was compared to kidney biopsies of these patients which were grouped into non proliferative and proliferative glomerulopathy. Results: 795 paired samples of urine sediment and kidney biopsies were examined and compared. Patients of non-proliferative glomerulopathy (Minimal change disease, Focal segmental glomerulosclerosis, amyloid and membranous nephropathy) showed features of Inactive sediment. Patients with proliferative glomerulopathy (focal proliferative glomerulonephritis [GN], Diffuse proliferative GN, Membranoproliferative GN, Mesangio-proliferative GN and crescentic GN) predominantly showed active sediment, with increase in percentage of dysmorphic red blood cells and formed elements. The sensitivity of this urine reporting system was 82.0%, specificity 74.4% with p value <0.001. Conclusions: This system of reporting urine sediment is a sensitive and efficient method of predicting the severity of underlying kidney disease and need for performing renal biopsy.