How does dehydration affect urine concentration?

Dehydration leads to an increase in urine specific gravity due to the body's efforts to conserve water. When an animal is dehydrated, the kidneys respond by reabsorbing more water from the renal tubules back into the bloodstream, resulting in the production of more concentrated urine. This means that the solutes, such as urea, creatinine, and various ions, are more concentrated in a smaller volume of urine, leading to a higher specific gravity reading.

In a dehydrated state, the kidneys produce less urine overall, but the urine that is produced is denser because of the increased concentration of waste products and solutes. Therefore, the specific gravity, which measures the density of urine compared to water, is elevated, confirming that urine concentration is increased during dehydration. This physiological mechanism is essential for maintaining electrolyte balance and proper hydration status in the body.