A patient with diarrhea shows signs of which condition if their urine is scant and dark yellow?

When a patient has diarrhea, they are losing a significant amount of fluid along with electrolytes, which can lead to a decreased volume of urine. Scant and dark yellow urine is a common indicator of dehydration, as it suggests that the body is conserving water in response to fluid loss.

In healthy individuals, urine is typically light yellow, indicating adequate hydration. However, when dehydration occurs, the kidneys concentrate urine to retain as much water as possible, resulting in less urine output and a darker color due to higher concentrations of waste products. This physiological response aims to prevent further water loss and maintain essential bodily functions.

While hyperhydration would involve an excess of fluids, which is contrary to the symptoms presented in this question, kidney stones and urinary tract infections typically have different urinary characteristics and are often associated with other symptoms. Thus, the signs of scant and dark yellow urine most directly point to dehydration in the context of diarrhea.