Serum phosphorus is a test to evaluate the level of mineral phosphorus in the blood. Phosphorus is a mineral required in your body for healthy bones, teeth, as well as nerve and muscle function. However, some amount of it is also present in your blood. Abnormally high or low levels of phosphorus in the blood can lead to various health complications. It may also hint towards an underlying health condition such as renal disease. A serum phosphorus test measures the amount of phosphate in a blood sample. Phosphorus imbalance in blood could be caused by poor nutrition, alcoholism, excess phosphate in your diet or kidney and liver diseases. Phosphorus test helps you identify conditions that might cause phosphorus imbalances in the blood. Phosphorus combines with other substances to form phosphate compounds. The serum phosphorus test detects the amount of inorganic phosphate in your blood. The deficiency of this mineral can cause hypophosphatemia. This is typically caused by acid-base imbalances, malnutrition, malabsorption, kidney disorders, etc. Excess intake of this mineral is called hyperphosphatemia and it can also be caused by a diet rich in phosphorus, low blood calcium, etc. A common cause of hyperphosphatemia in Indians is chronic kidney disease. Foods like chicken, dairy, nuts and soya are particularly high in phosphorus and should best be avoided if you have hyperphosphatemia. The serum phosphorus test result doesn’t reveal the exact underlying condition but helps with the overall diagnosis. Other tests may also be needed to find the root cause of the symptoms. The test requires a blood sample collected from a vein in your arm.