Which indicator is commonly used for measuring specific gravity in urine?

The use of Bromthymol blue as an indicator for measuring specific gravity in urine is based on its ability to change color in response to different pH levels, which can indirectly indicate the concentration of solutes in the urine. Specific gravity itself is a measure of the concentration of solutes in a liquid relative to water, and while Bromthymol blue is not a direct measure of specific gravity, it helps to assess urine concentration since urine pH can be influenced by the concentration of dissolved substances.

In urine analysis, specific gravity can provide information about hydration status and kidney function. When urine is concentrated, often due to dehydration or other health conditions, the pH can also fluctuate, which can be evaluated using pH indicators like Bromthymol blue.

The other listed indicators, such as Phenol red, Litmus paper, and Methyl orange, are not typically used for measuring specific gravity. They each have different properties or specific applications that do not align well with the assessment of urine concentration. For example, Phenol red is primarily a pH indicator and is used in different contexts, while Litmus paper is a simple tool for pH testing without a direct application to specific gravity. Methyl orange is another pH indicator that