Some NIH material is below on phosphorus. Many years ago now some one at Medicare decided you could save on health care costs if you deleted this test from the blood chemistry panel. Fact is that this test is really necessary to make sure you have some idea of how calcium is functioning and your level of bone health. Labs charge in the area of $120 extra for this test depending on the lab and where you live. Not much to be said for contining health costs.
Phosphorus is a treat minerals found in some foods such as Cereal Grains, Pasta, Pumpkin, Squash, and Watermelon Seeds. It plays an important role in proper cell functioning, regulation of calcium, strong bones and teeth, and for making ATP (adenosine triphosphate) and also the phospholipids that form all cell membranes(1a).
Phosphorus and bone health
Phosphorus, which constitutes hydroxyapatite with calcium, is a important component of bone. It is considered that there is no need to worry about the lack of phosphorus in the ordinary dietary habits, because a various of foods contain phosphorus. There is a report of parathyroid hormone and bone resorption markers are increased in case of low calcium/phosphorus intake ratio. In the Dietary reference intakes for Japanese, 2010, shows 3,000 mg/day as a tolerable upper intake level of phosphorus. Some issues such as the intake ratio of calcium to phosphorus and an effect of organic phosphorus and inorganic phosphorus remain to be solved. SOURCE