Phosphate is a charged particle (ion) that contains the mineral phosphorus. The body needs phosphorus to build and repair bones and teeth, help nerves function, and make muscles contract.
A phosphate test measures the amount of phosphate in a blood sample. Most (about 85%) of the phosphorus contained in phosphate is found in bones. The rest of it is stored in tissues throughout the body.
You may be asked not to eat anything from midnight before the test until after the test is over. Make sure your doctor knows about everything you’re taking, including prescription and over-the-counter medicine, herbal supplements, vitamins, and recreational or illegal drugs. After cleaning the skin on part of your arm, a technician will insert a needle into one of your veins. He may wrap an elastic band around the upper part of your arm to make that vein easier to find. Once enough blood goes into a tube, the technician will take off the band, pull out the needle, and stop the bleeding with a cotton ball or bandage. He’ll label the tube of blood, and it will be sent to a lab.
Adults need less phosphorus than children between the ages of 9 to 18, but more than children under 8 years old. The Linus Pauling Institute recommends the following daily intake:
- adults (19 years and older): 700 mg
- children (9 to 18 years): 1,250 mg
- children (4 to 8 years): 500 mg
- children (1 to 3 years): 460 mg
- infants (7 to 12 months): 275 mg
- infants (0 to 6 months): 100 mg
A high level of phosphate in the blood is usually caused by a kidney problem. The amount of phosphate in the blood affects the level of calcium in the blood