Homeostasis of Calcium and Phosphorus

Calcium and phosphorus, which are part of the teeth and bones, are important in the organism. As we need a large amount of these minerals, it is necessary to incorporate them in our diet. At the same time, these minerals are involved in other functions, among which we can mention (table 1):

Calcium | Phosphorus

|

Neuromuscular excitation | Enzyme regulation
Blood Coagulation | Functional integrity of cells and organic processes
Secretory processes | Supply of oxygen to the tissues
Membrane integrity | Buffer in urine and plasma
Transport in the plasma membrane | Energy storage through formation of molecules
Enzymatic reactions | Part of the DNA and cell membranes
Release of hormones and neurotransmitters | Involved in the supply of oxygen to the tissues
Bone mineralization | Bone mineralization

Table 1: Functions of calcium and phosphorus in the organism.

Calcium is the fifth element in order of abundance. An adult has almost 1 kg of calcium, which is combined with phosphorus forming hydroxyapatite crystals, mainly in bones. This represents 99% of the total calcium; the other 1 % is part of the extra and intracellular fluid. Therefore, we can say that the physiology of the metabolism of calcium and phosphate are closely related processes and therefore should be studied together [Kalantar-Zadeh 2010]. The amount of phosphorus in the organism differs from calcium levels because the ingestion of phosphorus in the diet is high and its absorption in the intestine has no limitations. In comparison, the ingestion of calcium is more limited in the diet, and its absorption by the intestine is less efficient [Peacock, 2010]. The excretion of both minerals is through the urine, regulated by the kidney. Phosphorus deficiency in the diet is rare and only generates bone loss, pain, debility and anorexia. Moreover, calcium deficiency can produce bone diseases, such as osteoporosis. The bones are more fragile and weaker, because of the loss of minerals. This deficiency is more common in women with menopause.

### References

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Kalantar-Zadeh K, Gutekunst L, Mehrotra R, Kovesdy CP, Bross R, Shinaberger CS, Noori N, Hirschberg R, Benner D, Nissenson AR, Kopple JD. 2010.

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Bergwitz C, Juppner H. 2010. Regulation of phosphate homeostasis by PTH, vitamin D, and FGF23. Annu Rev Med 61:91-104.

Parfitt AM. 1982. The coupling of bone formation to bone resorption: A critical analysis of the concept and of its relevance to the pathogenesis of osteoporosis. Metab Bone Dis Relat Res 4:1-6.

Prieto S. 1999. Control calcium metabolism, phosphorus and magnesium. En: Tresguerres JAF, ed. Human physiology , 2ª edition. Madrid: McGrawHill-Interamericana, 979-93.

Understanding sources of dietary phosphorus in the treatment of patients with chronic kidney disease. Clin J Am SocNephrol 5(3):519-530.

Cifuentes M.2001. Physiology of calcium and phosphorus metabolism. Indualimentos, 48-51.