What does the specific gravity of urine indicate?

The specific gravity of urine primarily indicates the concentration of solutes in the urine. It reflects the kidney's ability to concentrate or dilute urine, which is influenced by the hydration status of the individual and the functioning of the nephrons. A high specific gravity suggests concentrated urine, which can occur in situations of dehydration or when there are large amounts of solutes present, while a low specific gravity indicates dilute urine, often seen in conditions where excess fluid intake or certain kidney disorders is present.

Other options, like urine pH levels, presence of bacteria, and kidney size, do not directly relate to specific gravity. For instance, urine pH measures acidity or alkalinity but is assessed through different methods. Similarly, the presence of bacteria would require a culture or microscopic examination for confirmation, not through specific gravity measures. Lastly, kidney size is not discernible through urine analysis as it typically requires imaging studies for evaluation. Thus, the measurement of specific gravity serves as a vital indicator of solute concentration in urine.