This test provides a complete 24-hour picture of your body's phosphorus balance. Phosphorus is a mineral that works closely with calcium and vitamin D to maintain bone health, and its levels are regulated by your kidneys. This test measures the total amount of phosphorus excreted in your urine over a full day. It is essential for diagnosing and managing kidney disease, parathyroid disorders, and other bone-related conditions. The test requires a complete 24-hour urine collection. This is a key diagnostic piece for understanding your body's complex mineral balance.