Which finding in urinary sediment is more easily distinguished by polarized microscopy?

Which finding in urinary sediment is more easily distinguished by polarized microscopy?

• A. Oval fat bodies (lipids)
• B. Casts
• C. Red blood cells
• D. Ketone bodies

Answer: (A)

Polarized microscopy highlights substances that are birefringent, and lipid-containing structures in the urine—specifically oval fat bodies—show a distinctive Maltese cross pattern under polarized light. This makes them easy to recognize because the lipid droplets within the renal tubular cells refract light in a characteristic way, standing out from other sediment components. Casts, red blood cells, and ketone bodies do not exhibit this birefringent, Maltese cross appearance, so they aren’t as readily distinguished with polarized light.

Polarized microscopy highlights substances that are birefringent, and lipid-containing structures in the urine—specifically oval fat bodies—show a distinctive Maltese cross pattern under polarized light. This makes them easy to recognize because the lipid droplets within the renal tubular cells refract light in a characteristic way, standing out from other sediment components. Casts, red blood cells, and ketone bodies do not exhibit this birefringent, Maltese cross appearance, so they aren’t as readily distinguished with polarized light.