Final answer:
The absence of urine is termed anuria, a condition that may arise from acute renal failure or nephritis, and is distinguished from oliguria and polyuria, which signify decreased and increased urine output, respectively.
Step-by-step explanation:
The absence of urine is known as anuria. Anuria is a condition where there is no urine excreted, or the excretion is below 10 ml/day. It can be observed in acute renal failure and nephritis. Contrarily, oliguria refers to a significantly reduced urine output, typically less than 600 ml/day, and can result from conditions such as fever, shock, vomiting, and diarrhea.
Polyuria is the occurrence of an abnormally large volume of urine, over 2500 ml/day, and can be seen in diabetes insipidus, diabetes mellitus, diseases of the central nervous system, and amyloid degeneration of the kidney. Each of these conditions - anuria, oliguria, and polyuria - indicates alterations in kidney function and may require medical evaluation for proper diagnosis and treatment.