What Is Phosphorus Blood Level Test?

Submitted on March 27, 2012

Phosphorus blood levels are tested to determine the amount of the mineral phosphorus in our body. In its free form, phosphorus is present as an ion also known as inorganic phosphate. Phosphorus is an important element which is useful for the synthesis of bones and teeth. Apart from that phosphorous is also useful in maintaining normal functioning of the nerves and the contraction of the muscles. A huge chunk of the phosphorus present in our body is in the form of bones. If there is any extra phosphate in the blood, it is usually excreted by the kidney. However, if the kidneys are not functioning properly, phosphorus may be excreted in excessive quantities. If in the urine, there is a large amount of phosphorus, kidney failure is usually the cause.

The calcium and phosphate levels are inversely proportional to each other. If there is a rise in the calcium levels of the body, the phosphate levels decrease dramatically. However, there are some infections which may cause this inverse balance to be disrupted and therefore both phosphate and calcium tests are usually prescribed together.

Phosphorus Levels In Blood

Phosphorus is an important mineral that is found abundantly in the body. Along with calcium, phosphorus is responsible for building strong teeth and bones. Phosphorus also helps the body repair muscles, flush out waste from the kidneys, and store energy. The growth and regeneration of cells, tissues and muscles require a certain level of phosphorus in the blood at all times. Phosphorus also balances out the effect of other minerals such as zinc and magnesium and vitamins such as vitamin D.

How To Increase Your Intake of Phosphorous Through Diet?

The best way to increase your intake of phosphorus in your diet is through phosphorus rich foods such as whole grains, milk, and foods high in proteins. Phosphorus supplements are available but they should be taken only under strict supervision as they can react adversely with other medications. It is also important for the levels to stay around the 2.4 - 4.1 milligrams per deciliter mark which is the normal phosphorus levels in the body. This value may vary slightly and your doctor will be able to inform you about what is normal in your particular case.

Diseases That Cause High or Low Levels In Blood

Diseases such as anorexia, diabetes, and even alcoholism cause low phosphorus levels in the blood. People suffering from Celiac disease or Crohn's disease may also report low phosphorus levels leading to brittle and fragile bones, constant fatigue, and loss of appetite, weight fluctuations, anxiety, and stiff joints. Elevated phosphorus levels in the blood on the other hand are a more common problem.

High phosphorus levels are caused by kidney disease or due to the excessive consumption of dietary phosphorus. The body requires a fine balance of phosphorus and calcium in the blood. When there are higher levels of phosphorus, health issues such as osteoporosis and gum and teeth problems begin to develop. Symptoms of high phosphorus levels in blood indicate several medical conditions such as kidney disorders, malnutrition and other gastrointestinal disorders, and calcium and bone problems.

Reasons For Conducting This Test

Simple blood tests can be done to check the levels of phosphorus in the body. It is important to ensure that medications such as diuretics, antacids, and laxatives are not taken before the test as they may affect the results. Test results that show a higher than normal level of phosphorus in the blood (hyperphosphatemia) may indicate diseases such as liver disease, renal failure, excess of vitamin D, hypocalcemia, and hypoparathyroidism. Low phosphorus levels in the blood (hypophosphatemia) may indicate health issues such as malnutrition, low intake of vitamin D, hypercalcemia, and hyperparathyroidism.

A phosphate test is usually prescribed to check for proper functioning of the kidneys, bones and parathyroid glands. To regulate the parathyroid hormone, phosphate is needed.

The levels of phosphates are usually higher in children because their bone growth is still actively occurring. For adults, the normal values are 3.0 to 4.5 milligrams per deciliter and in children the normal levels are 4.5 to 6.5 milligrams per deciliter. The normal levels range in babies is quite similar to those of children.

Serum phosphate levels, if high, are caused due to kidney diseases or a parathyroid gland which is not functioning properly and is producing low amounts of the parathyroid hormone. Fractures that are healing, diabetic ketoacidosis when left untreated, rhabdomyolysis and acromegaly are also causes for high blood phosphates level. In the presence of excess of vitamin D, phosphate levels of the blood may increase significantly. Decreased magnesium levels and pregnancy are other causes for this increase.


In adults, this is a simple blood test, wherein blood sample is drawn from a vein in your arm. If the phosphate level of a newborn baby needs to be checked then a heel stick approach is used. In this procedure, blood sample is collected from the heel of your baby.

Interpretation of Test Results

Results of a phosphate test are usually available in a couple of hours. Normal range of phosphate in blood for adults is 3 to 4.5 mg/dL (milligrams per deciliter). In children, phosphate levels are generally higher given bone growth and the normal range is 4.5 to 6.5 mg/dL and in infants the range is 4.3 to 9.3 mg/dL.

If your blood phosphate level is high this could be indicative of a kidney disease, bone disease, hypoparathyroidism, healing fractures, acromegaly and rhabdomylosis.

Other factors that can sometimes cause phosphate levels to rise include excess vitamin D, decrease in magnesium levels in the body and for women, pregnancy.

Low phosphate levels, on the other hand are indicative of hyperparathyroidism, osteomalacia, kidney and liver infections, lack of vitamin D and intense burns.

A few other factors that can cause low phosphate levels include alcohol abuse, severe malnutrition, increase in calcium levels as well as a condition like sprue, wherein the intestines are unable to absorb nutrients efficiently.

Low phosphate levels also affect those who have type 2 diabetes or if a diabetic person is treated with insulin. Studies indicate that children with low phosphate levels tend to grow slower than kids with normal phosphate levels.