Physiology, Phosphate

Excerpt

Phosphate is an essential electrolyte in the human body as it constitutes about 1% of the total body weight. In an adult, the normal serum phosphate level ranges between 2.5 to 4.5 mg/d L. The normal serum levels of phosphate tend to decrease with age and its highest levels i.e., 4.5 to 8.3 mg/dL are seen in infants, about 50% higher than adults; this is because infants and children need more phosphate for their growth and development.

Phosphate is readily available in our diet as it is present in almost all-natural foods. Important dietary sources of phosphate are milk, cereal grains, fish, poultry, eggs, meat, and peanuts.

Of the total phosphate in the body, 85% is n the bones and teeth,1% in the extracellular fluid and the remaining 14% is distributed in other tissues where it is an important constituent of cell membranes, nucleic acids, high energy phosphate esters (ATP) and intracellular signaling proteins.

In the skeleton, the majority of the phosphate is in combination with calcium in the form of hydroxyapatite crystals, and the rest is present in the form of amorphous calcium phosphate. There are two forms of phosphate present in the serum, dihydrogen phosphate( H2PO4) and mono hydrogen phosphate (HPO4); the balance between these two forms depends on the acid-base status of the body.