Which condition is characterized by an increase in urination volume?

Polyuria is the condition characterized by an increase in urination volume, often defined as the production of more than 3 liters of urine in a 24-hour period. This increase can occur due to various reasons, such as uncontrolled diabetes mellitus, diabetes insipidus, or certain medications. The underlying mechanisms often involve changes in the body's ability to concentrate urine or excessive fluid intake.

In contrast, conditions like anuria represent a complete cessation of urine production, oliguria signifies a reduced urine output (typically less than 400 mL per day), and hematuria indicates the presence of blood in urine, which does not relate to the volume produced. Therefore, polyuria distinctly marks an increase in urine volume, making it the correct choice.