Phosphorus (phosphate, PO4)
Phosphorus, combined with oxygen, is present in the body in the form of phosphates. It is found in the highest proportion in the bones and striated muscle tissues, and in a very small proportion in nerve tissues and in the blood plasma as well. Phosphates play an important role in cellular metabolism and energy production, bone growth and metabolism, muscle and nerve function, and maintaining the body’s acid-base balance.
The body’s phosphate level is closely related to the level of calcium in the blood, which is regulated by the parathyroid hormone produced in the parathyroid gland, at the same time forming the body’s phosphate content.
Phosphorus enters the body with food, utilizes the amount absorbed from the intestines and excreted by the kidneys. Foods high in phosphorus include cereals (rye, wheat), legumes (beans, peas, lentils), dairy products, and red meats. However, convenience food and carbonated soft drinks contain a lot of phosphorus, which can contribute to excessive phosphorus intake, so it is advisable to reduce their consumption to maintain adequate calcium levels.
What does the test show?
Examination of the body’s phosphorus level, i.e. the concentration of phosphate, helps diagnose certain bone and endocrine (parathyroid, kidney) diseases and helps determine the severity of conditions affecting the intestinal tract (e.g. malabsorption).
In which cases is it recommended to perform the test?
Due to its diversified role, determining the level of phosphate as one of the basic ions is most often part of general laboratory examination.
Phosphorus testing is most often ordered by a specialist if the body’s calcium utilization is inadequate, which can be shown by previous laboratory tests, or if symptoms suggest it (fatigue, muscle cramps, muscle weakness).
The test can also be used to diagnose diseases of the intestinal tract that inhibit the absorption of calcium, magnesium and phosphorus, as well as kidney failure and hormonal problems.
What sample is needed for the test?
The test can be performed on a blood sample taken from a vein. This test does not require an empty stomach.
A 10 ml sample of urine collected over 24 hours is required for urine testing.
What can the result indicate?
Phosphate levels lower than normal can be caused by a phosphorus-deficient diet (malnutrition, alcoholism), high calcium levels, low potassium levels, treatment of ketoacidosis as a complication of diabetes, osteomalacia due to vitamin D deficiency, excessive use of diuretics and acid sequestrants.
Higher than normal phosphorus levels can be caused by kidney or parathyroid problems (hypoparathyroidism), ketoacidosis as a complication of diabetes, too low level of calcium (hypocalcaemia) or phosphate supplementation. Excessively high phosphorus levels can cause calcification in the long run, most often in the kidneys.
What to do after the test?
Due to the multiple role of phosphorus in the body, the result is for diagnostic purposes only with the results of other tests, so in all cases, after the test, consult the doctor or treating physician who ordered the test.