General information

Calcium is a soft grayish-white metallic element, one of the alkaline earth metals (symbol Ca; atomic no. 20). It is found in sources such as lewisite (calcium antimonate), colemanite and pandermite (calcium borates); ankerite, aragonite, calcite, chalk, dolomite, and stromatolite (calcium carbonates); hydrophilite (calcium chloride); powellite (calcium molybdate); whewellite (calcium oxalate); autunite (calcium phosphate); anorthite, apophyllite, chabazite, datolite, epidote, eudialite, feldspar, gyrolite, hornblende, margarite, melilite, monticellite, nephrite, pectolite, phillipsite, piedmontite, prehnite, scapolite, scawtite, scolecite, thaumasite, titanite, vesuvianite, wollastonite, and zeolite (calcium silicates); glauberite, gypsum, and polyhalite (calcium sulfates); perovskite (calcium titanate); and scheelite (calcium tungstate). Calcium phosphate is a major constituent of bones (apatite).

Uses

Salts of calcium are used as a source of calcium:

  • to treat hypocalcaemia (for example calcium gluconate);

  • to treat hyperphosphatemia (for example calcium acetate, calcium carbonate);

  • to treat hyperkalemia (calcium polystyrene sulfonate; see monograph on Polystyrene sulfonates);

  • to treat and prevent osteomalacia and osteoporosis (in combination with vitamin D or a bisphosphonate);

  • as antacids (for example calcium hydroxide and calcium carbonate).

However, although calcium salts can produce short-term relief from dyspepsia, calcium ions stimulate antral gastrin release, and hence gastric acid secretion, making them unsuitable for long-term treatment of peptic disorders [ ].

Other uses of calcium salts incidental to the calcium they contain include:

  • in wound dressings (calcium alginate);

  • to prevent methotrexate toxicity (calcium folinate and levofolinate);

  • in lead poisoning (sodium calcium edetate).

Organs and systems

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