Which of the following is used to measure the specific gravity of urine?

• A. Microscope
• B. Refractometer
• C. Agar plate
• D. Flotation device

Answer: (B)

Urine specific gravity reflects how concentrated the urine is, and the most direct way to determine it is with a refractometer. A refractometer measures how much light bends as it passes through the urine; this refraction correlates with the solution’s density, giving a specific gravity value quickly from a tiny sample. Temperature can affect readings, so many refractometers include temperature compensation or require calibration with distilled water first.

The other tools aren’t used for this measurement because they serve different purposes: a microscope is for examining cells, crystals, or casts in urine; an agar plate is for growing microorganisms; and a flotation device is used to separate parasitic eggs or other components in stool samples, not to assess urine density.