Phosphorus
Also known as: P; PO4; Phosphate
Formal name: Inorganic Phosphate
The Test
How is it used?
Phosphorus testing is very important in people who are malnourished or who are being treated for ketoacidosis. Phosphorus testing is used to help diagnose and evaluate the severity of conditions and diseases that affect the gastrointestinal tract, interfering with the absorption of phosphorus, calcium, and magnesium. Testing also can help to diagnose disorders that affect the kidneys, interfering with mineral excretion and conservation, and phosphorus levels are carefully monitored in people with kidney failure.
When a person has a known problem that affects their phosphorus and/or calcium levels, phosphorus levels may be monitored regularly to determine the effectiveness of treatment. Usually, it is not a stand-alone test.
While phosphorus levels are most commonly performed on blood samples, timed urine phosphorus measurements also may be used to monitor phosphorus elimination by the kidneys.
When a person has a known problem that affects their phosphorus and/or calcium levels, phosphorus levels may be monitored regularly to determine the effectiveness of treatment. Usually, it is not a stand-alone test.
While phosphorus levels are most commonly performed on blood samples, timed urine phosphorus measurements also may be used to monitor phosphorus elimination by the kidneys.
When is it ordered?
A phosphorus test is often ordered to help diagnose diseases and conditions that cause problems with the body’s utilization of calcium. The test may aid 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 level and, to a lesser degree, phosphorus levels.
Although abnormal phosphorus levels usually cause no symptoms, phosphorus testing often is performed as a follow-up to an abnormal calcium level and/or related symptoms, such as fatigue, muscle weakness, cramping, or bone problems.
Phosphorus testing may be ordered when symptoms suggest kidney and gastrointestinal disorders.
If conditions causing abnormal phosphorus and/or calcium levels are found, testing for both may be ordered at regular intervals to monitor treatment effectiveness.
If you have a kidney disorder, kidney stones, or uncontrolled diabetes, your doctor may monitor phosphorus levels to make sure that you are not excreting or retaining excessive amounts.
Although abnormal phosphorus levels usually cause no symptoms, phosphorus testing often is performed as a follow-up to an abnormal calcium level and/or related symptoms, such as fatigue, muscle weakness, cramping, or bone problems.
Phosphorus testing may be ordered when symptoms suggest kidney and gastrointestinal disorders.
If conditions causing abnormal phosphorus and/or calcium levels are found, testing for both may be ordered at regular intervals to monitor treatment effectiveness.
If you have a kidney disorder, kidney stones, or uncontrolled diabetes, your doctor may monitor phosphorus levels to make sure that you are not excreting or retaining excessive amounts.
What does the test result mean?
Dietary deficiencies in phosphorus are rare but may be seen with alcoholism and malnutrition. Low levels of phosphorus (hypophosphatemia) may also be due to or associated with:
- Hypercalcemia, especially due to hyperparathyroidism
- Overuse of diuretics
- Severe burns
- Diabetic ketoacidosis (after treatment)
- Hypothyroidism
- Hypokalemia
- Chronic antacid use
- Rickets and osteomalacia (due to Vitamin D deficiencies)
Higher than normal levels of phosphorus (hyperphosphatemia) may be due to or associated with:
- Kidney failure
- Hypoparathyroidism (underactive parathyroid gland)
- Diabetic ketoacidosis (when first seen)
- Phosphate supplementation
Is there anything else I should know?
Abnormally high levels of phosphorus can lead to organ damage due to calcification.
Phosphate levels are normally higher in children than in adults because their bones are actively growing. Low phosphate levels in children can inhibit bone growth.
Soft drinks and pre-packaged food items are high in phosphorus content, which some nutritionists believe contributes to over consumption of phosphorus.
Test results may be impacted by the use of enemas and laxatives containing sodium phosphate, excess Vitamin D supplements, and by intravenous glucose administration.
Phosphate levels are normally higher in children than in adults because their bones are actively growing. Low phosphate levels in children can inhibit bone growth.
Soft drinks and pre-packaged food items are high in phosphorus content, which some nutritionists believe contributes to over consumption of phosphorus.
Test results may be impacted by the use of enemas and laxatives containing sodium phosphate, excess Vitamin D supplements, and by intravenous glucose administration.
