Arylsulfatase A (ASA) analysis in 24-hour urine is a test used to evaluate the level of the enzyme arylsulfatase A in the body. This enzyme is essential for breaking down sulfur-containing compounds, and the test helps diagnose certain genetic disorders, such as Niemann-Pick disease. A 24-hour urine sample is collected, allowing accurate measurement of enzyme levels and providing insight into nervous system health and biochemical functions.