A Phosphorus test measures the level of phosphate, a mineral that plays an essential role in bone strength, energy production, and nerve and muscle function. Abnormal phosphorus levels may indicate issues related to kidneys, bones, parathyroid glands, or nutritional imbalances. High levels are often linked to kidney disorders, while low levels may be caused by malnutrition, alcohol use, hormonal problems, or certain medications. Doctors usually recommend this test when symptoms such as weakness, bone pain, fatigue, or muscle cramps are present.

For the Phosphorus test, a small blood sample is collected from a vein. Fasting for 8–12 hours may be recommended, depending on your doctor’s instructions, as food intake can affect phosphorus levels. This test is often performed alongside calcium, vitamin D, and kidney function tests to give a complete picture of metabolic and bone health.