What medical term is used for the absence of urine formation?

The term "anuria" specifically refers to the complete absence of urine formation or the production of less than 100 milliliters of urine in a 24-hour period. This condition indicates a significant issue with kidney function or systemic problems affecting urine production. In contrast, "oliguria" describes a reduction in urine output but not a complete absence; it refers to low urine output, typically defined as less than 400 milliliters per day. "Polyuria," on the other hand, is characterized by excessive urine production, often seen in conditions like diabetes mellitus. "Urinary retention" refers to the inability to empty the bladder completely, leading to a buildup of urine, but does not describe the absence of urine production itself. Therefore, anuria is the correct term for the total lack of urine formation.