In an adult body there is 20 mol (620 g) phosphorus, entirely in the form of phosphate. It is equally distributed between extracellular and intracellular compartments.

Intracellular phosphate is an integral component of phospholipids and phosphoproteins (organic phosphate). A small but very important fraction exists intracellularly as "inorganic phosphate" - participating in high energy transfer reactions.

85% of extracellular phosphate is inorganic as hydroxyapatite. In plasma (serum) most phosphate is inorganic. 15% of this is protein bound.

The reference range for serum phosphate is 0.8-1.4 mmol/l.

Last reviewed 03/2021