Phosphorus - serum; HPO4-2; PO4-3; Inorganic phosphate; Serum phosphorus
The phosphorus blood test measures the amount of phosphate in the blood.
A blood sample is needed.
Your health care provider may tell you to temporarily stop taking medicines that may affect the test. These medicines include water pills (diuretics), antacids, and laxatives.
Do not stop taking any medicine before talking to your provider.
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away.
Phosphorus is a mineral the body needs to build strong bones and teeth. It is also important for nerve signaling and muscle contraction.
This test is ordered to see how much phosphorus is in your blood. Kidney, liver, and certain bone diseases can cause abnormal phosphorus levels.
Normal values range from:
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
A higher than normal level (hyperphosphatemia) may be due to many different health conditions. Common causes include:
A lower than normal level (hypophosphatemia) may be due to:
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
Chonchol M, Smogorzewski MJ, Stubbs JR, Yu ASL. Disorders of calcium, magnesium, and phosphate balance. In: Yu ASL, Chertow GM, Luyckx VA, Marsden PA, Skorecki K, Taal MW, eds. Brenner and Rector's The Kidney. 11th ed. Philadelphia, PA: Elsevier; 2020:chap 18.
Klemm KM, Klein MJ. Zhang Y. Biochemical markers of bone metabolism.In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 16.
Kliegman RM, Stanton BF, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM. Electrolyte and acid-base disorders. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 68.BACK TO TOP
Review Date: 11/6/2021
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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