LOW-COST POLARIZED LIGHT MICROSCOPY FOR VISUALIZATION OF OVAL FAT BODIES IN URINE SEDIMENT: A PRACTICAL DIAGNOSTIC APPROACH

Abstract

Oval fat bodies are lipid-laden renal tubular cells commonly observed in urinary sediment and are considered a hallmark of nephrotic syndrome. Their identification is enhanced by polarized light microscopy due to their characteristic birefringence. However, access to polarized microscopes remains limited in many low-resource laboratory settings. This study describes and evaluates a low-cost polarized light microscopy technique adapted from a previously described method for malaria pigment detection to visualize oval fat bodies and lipid droplets in urine sediment. A conventional bright-field light microscope was modified using inexpensive polarizing materials costing approximately USD 7. Urine sediment samples from patients with heavy proteinuria were examined under both conventional and polarized light. The ability of the modified system to detect birefringent lipid structures was assessed. The modified microscope successfully demonstrated classic Maltese cross birefringence in oval fat bodies, circular fat droplets, and fatty casts. Differentiation from morphologically similar urinary elements such as red blood cells, yeast, calcium oxalate crystals, and starch particles was feasible using polarized light characteristics. Low-cost polarized light microscopy provides an effective, affordable method for identifying oval fat bodies in urine sediment. This approach has significant potential to enhance diagnostic capability for nephrotic syndrome in resource-limited clinical laboratories.