How Phosphorus in Blood is presented?
Phosphorus in Blood is Present as:
1. Inorganic phosphorus in the form of HPO4 or H2PO4
2. Organic or ester phosphorus such as glycerophosphate, nucleotide phosphate etc.
3. Lipid phosphorus such as lecithin, cephalin etc.
4. A small amount of residual phosphorus
Phosphate is absorbed from the jejunum with calcium and is deposited in the skeleton or mobilized from it in a fixed proportion to calcium. It is excreted by kidneys following glomerular filtration and active tubular re-absorption. The latter process is inhibited by PTH which thereby increases phosphate excretion. Serum inorganic phosphorus levels are measured in terms of phosphate ions, for ionised free phosphate does not circulate.