Serum Phosphate

Specimen Required

3-5cc Clotted Blood or Serum

Fasting Required

Purpose of the Test

To evaluate the level of phosphate in your blood and to aid in the diagnosis of conditions known to cause abnormally high or low levels

When this test is required

A phosphate test is often requested to help diagnose diseases and conditions that cause problems with the body’s utilisation of calcium. The test may help in the diagnosis of problems with hormones, such as parathyroid hormone (PTH) and Vitamin D, which functions as a hormone, that regulate the body’s calcium concentration and, to a lesser degree, phosphate.Although abnormal phosphate levels usually cause no symptoms (with the exception of very low levels), phosphate testing often is performed as a follow-up to an abnormal calcium level and/or related symptoms, such as fatigue, muscle weakness, cramps or bone problems.Phosphate testing may be requested when symptoms or other tests suggest kidney and/or disorders of the digestive system.A phosphate test may be requested in people who are treated for malnourishment as this can cause the phosphate level in the blood to fall.If conditions causing abnormal phosphate and/or calcium levels are found, testing for both may be requested at regular intervals to monitor treatment effectiveness.If you have a kidney disorder, kidney stones, or uncontrolled diabetes, your doctor may monitor phosphate levels to make sure that you are not loosing or retaining excessive amounts.

What the Test Detects

The serum phosphate test measures the amount of inorganic phosphate in your blood plasma (the liquid part of blood). In the body, phosphorus is combined with oxygen to form a variety of phosphates (PO4). Phosphates are vital for energy production, muscle and nerve function, and bone growth. They also play an important role as a buffer, helping to maintain the body’s acid-base balance. About 70% to 80% of the phosphates are…The serum phosphate test measures the amount of inorganic phosphate in your blood plasma (the liquid part of blood). In the body, phosphorus is combined with oxygen to form a variety of phosphates (PO4). Phosphates are vital for energy production, muscle and nerve function, and bone growth. They also play an important role as a buffer, helping to maintain the body’s acid-base balance. About 70% to 80% of the phosphates are combined with calcium to help form bones and teeth, about 10% are found in muscle, and about 1% is in nerve tissue. The rest is found within cells throughout the body, where it is mainly used to store energy; about 1% of total body phosphate is found within plasma. Most phosphate in the body comes from dietary sources. A variety of foods, such as beans, peas and nuts, cereals, dairy products, eggs, beef, chicken, and fish contain significant amounts of phosphate. The body maintains phosphate levels in the blood by regulating how much it absorbs from the intestines and how much it excretes or conserves in the kidneys. How is the sample collected for testing? A blood sample is obtained by inserting a needle into a vein in the arm. If a timed urine sample is required, you will be asked to save all of your urine over a set time period (usually 24 hours). Is any test preparation needed to ensure the quality of the sample? Overnight fasting may be required for a blood sample; follow any instructions that you are given. See MoreSee Less

Preparation for the Test

Overnight fasting may be required for a blood sample; follow any instructions that you are given.

Sample Requirements

A blood sample taken from a vein in your arm, or a fasting or timed urine collection (usually a 24-hour sample)

Additional Notes

Abnormally high levels of phosphate can lead to organ damage due to calcification (calcium phosphate deposits in organs, such as the kidneys).Phosphate levels are normally higher in young children than in adults because their bones are actively growing. Low phosphate levels in children can inhibit bone growth. Very low levels of phosphate are rare but require swift medical attention.Soft drinks and pre-packaged food items are high in phosphate content, sometimes as phosphoric acid, which some nutritionists believe contributes to over consumption of phosphorus.Test results may be affected by the use of enemas and laxatives containing sodium phosphate, excess Vitamin D supplements, and by intravenous glucose administration.

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