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

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. 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. 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. 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.