Test Details & Preparation
A phosphorus blood test is done to assess phosphorus levels in the blood. Doctors may order a phosphorus test to help diagnose or monitor certain conditions such as kidney disorders (to see if the kidneys are excreting or retaining too much phosphorus) gastrointestinal and nutritional disorders (to look for problems with intestinal absorption or malnutrition) and calcium and bone problems.
No special preparations are needed for this test. However, certain drugs - especially antacids, laxatives, and diuretics - might affect the test results, so tell your doctor about any medications you are taking.
The blood sample will be processed by a machine. The results are commonly available after a few hours or the next day.
If phosphorus levels are found to be either elevated or deficient, further testing may be necessary to determine what's causing the problem and how to treat it.
Low levels of phosphorus in the blood may be due to or associated with hypercalcemia, overuse of diuretics, malnutrition, alcoholism, severe burns, hypothyroidism, etc.
Higher than normal levels of phosphorus in the blood may be due to or associated with kidney failure, liver disease, hypoparathyroidism or increased dietary intake.
Abnormally high levels of phosphorus can lead to organ damage due to calcification, deposits of calcium phosphate in the tissues. This is rare, however, and it is more common that high phosphorus levels lead to cardiovascular disease or osteoporosis.