Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

What is measured by a refractometer?

1. pH

2. Albumin

3. Specific gravity

4. Bilirubin

The correct answer is: Specific gravity

A refractometer is an instrument used to measure the refractive index of a solution, which is closely related to the concentration of solutes in that solution. Specifically, it is commonly used to measure the specific gravity of a liquid by determining how much light is bent (or refracted) as it passes through the sample. This property allows healthcare professionals and laboratory technicians to assess the concentration of various substances within urine, serum, or other fluids, thus providing valuable information about hydration status, kidney function, and potential disease conditions. In contrast, pH (the measure of hydrogen ion concentration), albumin (a protein level), and bilirubin (a pigment resulting from the breakdown of red blood cells) require different types of testing methods, such as colorimetric assays or specialized analyzers, rather than measuring the refractive index. Each of these assays serves a distinct purpose, and refractometers are specifically tailored for evaluating specific gravity and similar metrics.