Inorganic Phosphorus Test

Phosphorus tests are most often ordered along with other tests, such as those for calcium, parathyroid hormone (PTH), and/or vitamin D, to help diagnose and/or monitor treatment of various conditions that cause calcium and phosphorus imbalances. Phosphorus deficiencies may be seen with malnutrition, malabsorption, acid-base imbalances, hypercalcemia, and with disorders that affect kidney function. Soft drinks and pre-packaged food items are high in phosphorus content, which some nutritionists believe contributes to over-consumption of phosphorus. Blood and urine levels of phosphorus may be affected by the use of enemas and laxatives containing sodium phosphate, excess dietary vitamin D supplements, and by intravenous glucose administration.

Many medications can affect your phosphorus levels, including antacids, vitamin D supplements and intravenous glucose. Medications that contain sodium phosphate can also affect your phosphorous levels. Be sure you tell your doctor about any medications you are taking. They may instruct you to temporarily stop using medications that could interfere with your test results.

Phosphorus tests are most often ordered along with other tests, such as those for calcium, parathyroid hormone (PTH), and/or vitamin D, to help diagnose and/or monitor treatment of various conditions that cause calcium and phosphorus imbalances. Phosphorus tests are used in evaluating body system functions by monitoring phosphorous levels in relation to other electrolytes. It is specifically used to evaluate renal function in at-risk patients. While phosphorus tests are most commonly performed on blood samples, phosphorus is sometimes measured in urine samples to monitor its elimination by the kidneys.

You don’t typically need to fast before this test. Your doctor will let you know if they want you to fast for any reason. The test involves a simple blood draw. Your doctor or a nurse will use a small needle to collect a sample of blood from a vein in your arm or hand. They will send the sample to a laboratory for analysis. When conditions causing abnormal phosphorus and/or calcium levels are found, testing for both may be ordered at regular intervals to monitor treatment effectiveness. When someone has diabetes or signs of an acid-base imbalance, a health practitioner may sometimes monitor phosphorus levels.