Phosphorus is a mineral that plays a crucial role in bone health, energy production, and acid-base balance in the body. This test measures the amount of phosphorus in the blood, which can help diagnose various medical conditions. High phosphorus levels (hyperphosphatemia) can occur in kidney disease, hypoparathyroidism, and certain bone disorders. Low phosphorus levels (hypophosphatemia) can result from malnutrition, alcoholism, diabetes, and certain medications. Phosphorus works closely with calcium and vitamin D to maintain bone strength and structure. Abnormal phosphorus levels can affect muscle function, bone health, and overall metabolism. This test is commonly ordered as part of routine health screenings, when evaluating bone disorders, or when monitoring patients with kidney disease or other chronic conditions.