What is the difference between phosphate and phosphorus and how are they measured in clinical medicine?
Phosphorus is a critical element in physiology. Phosphorus is an essential component of bone (hydroxyapatite), DNA, lipid membranes (phospholipids), signal molecules (phosphorylation activates numerous enzymes), and chemical energy storage (adenosine triphosphate and creatine phosphate). In the serum, phosphorus circulates as phosphate, PO 4 −3 usually with one or two protons, H 2 PO − 4 or HPO 4 2−
The atomic weight of phosphorus is 31 g/mole and the average valence (pH 7.4) is 1.8. Normal serum phosphorus is 2.5 to 4.5 mg/dL. This converts to 0.8 to 1.45 mmol/L or 1.45 to 2.61 mEq/L.
