calcium (Ca) [kal´se-um]
a chemical element, atomic number 20, atomic weight 40.08. (See Appendix 6.) Calcium is the most abundant mineral in the body. In combination with phosphorus it forms calcium phosphate, the dense, hard material of the bones and teeth. It is an important cation in intracellular and extracellular fluid and is essential to the normal clotting of blood, the maintenance of a normal heartbeat, and the initiation of neuromuscular and metabolic activities.
Within the body fluids calcium exists in three forms. Protein-bound calcium accounts for about 47 per cent of the calcium in plasma; most of it in this form is bound to albumin. Another 47 per cent of plasma calcium is ionized. About 6 per cent is complexed with phosphate, citrate, and other anions.
Ionized calcium is physiologically active. One of its most important physiological functions is control of the permeability of cell membranes. Parathyroid hormone, which causes transfer of exchangeable calcium from bone into the blood stream, maintains calcium homeostasis by preventing either calcium deficit or excess.Hypercalcemia:
This is when the level of serum calcium rises above normal; neuromuscular activity begins to diminish. Symptoms include lethargy, muscle weakness (which, as the level of calcium increases, can progress to depressed reflexes and hypotonic muscles), constipation, mental confusion, and coma. The heartbeat also slows, which potentiates the effects of digitalis.Hypocalcemia:
This is a serum level of calcium that is below normal; it is manifested by increased neuromuscular irritability. When there is a deficit of ionized calcium, the nerve cells become more permeable, allowing leakage of sodium and potassium from the cells. This produces excitation of the nerve fibers and triggers uncontrollable activity of the skeletal muscles. Hence, as the calcium level continues to drop, the patient begins to experience muscle twitching and cramping, grimacing, and carpopedal spasm, which can quickly progress to tetany, laryngospasm, convulsions, cardiac arrhythmias, and eventually to respiratory and cardiac arrest. Relatively early signs of hypocalcemia are a positive trousseau's sign
and a positive chvostek's sign
Dietary sources of calcium include dairy products (such as milk and cheese), soybeans, fortified orange juice, dark green leafy vegetables (such as mustard greens and broccoli), sardines, clams, and oysters. The recommended dietary allowance
of calcium for children aged 4 to 8 is 800 mg, and that for women aged 50 to 70 is 1200 mg. (See tables in the Appendices for recommended dietary allowances
across the life span.) It is difficult to meet these requirements without including milk or milk products in the daily diet. The most familiar calcium deficiency disease is rickets
, in which the bones and teeth soften. However, it is believed that a large number of people suffer from subclinical calcium deficiency because of poor eating habits. Since calcium is essential to the formation and maintenance of strong bones, an adequate intake is important in the prevention of osteoporosis
the calcium salt of acetic acid; administered orally as a source of calcium and as a phosphate binder
, such as in patients with end-stage renal disease
. Also used as a pharmaceutical buffering agent.
an insoluble salt occurring naturally in bone, shells, and chalk; used as an antacid
, calcium supplement, and phosphate binder
, and for treatment of osteoporosis
calcium channel blocker
(calcium channel blocking agent
) a drug such as nifedipine
, or verapamil
that selectively blocks the influx of calcium ions through a calcium channel
of cardiac muscle and smooth muscle cells; used in the treatment of Prinzmetal's angina
, chronic stable angina
, and cardiac arrhythmias
. Calcium channel blocking agents act to control arrhythmias by slowing the rate of sinoatrial node discharge and the conduction velocity through the atrioventricular node. They act in vasospastic angina to relax and prevent coronary artery spasm. The mechanism of action in classical angina is a lowering of myocardial oxygen utilization by dilating peripheral arteries and thereby reducing total peripheral resistance and the work of the heart.
Physiologic activity of calcium channel blockers. (Data from Hardman J. and Limbird L., editors: Goodman and Gilman's The Pharmacologic Basis of Therapeutics, 9th ed., New York, McGraw-Hill, 1996; and the National Institutes of Health: The Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure, NIH Pub. No. 98-4080, Washington, DC, GPO, 1998.) From Edmunds and Mayhew, 2000.
a salt used in solution to restore electrolyte balance, treat hypocalcemia
, and act as a treatment adjunct in cardiac arrest and in magnesium
a salt used as a calcium replenisher; also used in the treatment of hyperphosphatemia in renal osteodystrophy
a calcium replenisher, used as a nutritional supplement and for the treatment of hypocalcemia
; administered orally.
a calcium salt administered intramuscularly or intravenously in the prevention and treatment of hypocalcemia
and as an electrolyte replenisher.
a calcium salt administered intravenously or orally in the treatment and prevention of hypercalcemia
and as a nutritional supplement. It is also administered by injection as a treatment adjunct in cardiac arrest and in the treatment of hyperkalemia
calcium hydroxide an astringent compound used topically in solution or lotions.
a calcium replenisher, administered orally in the treatment and prevention of hypocalcemia
and as a nutritional supplement.
a salt of oxalic acid, which in excess in the urine may lead to formation of oxalate urinary calculi
calcium oxide lime
a calcium salt of the dextrorotatory isomer of the B vitamin pantothenic acid
; used as a nutritional supplement. It is also available as racemic calcium pantothenate,
which is a mixture of the dextrorotatory and levorotatory isomeric forms.
calcium phosphate a salt containing calcium and the phosphate radical; dibasic and tribasic calcium phosphate are used as sources of calcium.
a hydrophilic agent used as a bulk laxative
a salt used as an antifungal
preservative in foods and as a topical antifungal agent
calcium pyrophosphate deposition disease
an acute or chronic inflammatory arthropathy
caused by deposition of crystals of calcium pyrophosphate
dihydrate in the joints and synovial fluid and chondrocalcinosis
. Clinically, it may resemble numerous other connective tissue diseases such as arthritis
, or it may be asymptomatic. Acute attacks are sometimes called pseudogout
a chemical element, atomic number 20, atomic weight 40.08, symbol Ca. See Table 6. Calcium is the most abundant mineral in the body. In combination with phosphorus it forms calcium phosphate, the dense, hard material of the bones and teeth. It is an important cation in intra- and extracellular fluid and is essential to the normal clotting of blood, the maintenance of a normal heartbeat, and the initiation of neuromuscular and metabolic activities.
Within the body fluids calcium exists in three forms. Protein-bound calcium accounts for about 47% of the calcium in plasma; most of it in this form is bound to albumin. Another 47% of plasma calcium is ionized. About 6% is complexed with phosphate, citrate and other anions.
Ionized calcium is physiologically active. One of its most important physiological functions is control of the permeability of cell membranes. Parathyroid hormone, which causes transfer of exchangeable calcium from bone into the bloodstream, and calcitriol maintain calcium homeostasis by preventing either calcium deficit or excess.
used extensively as a spray in orchards, constituting a poison hazard for livestock.
avian calcium poisoning
excess calcium in the avian diet, especially in diets low in phosphorus causes nephrosis, visceral gout and urolithiasis.
the balance between calcium intake and losses in feces and urine.
an insoluble salt occurring naturally in bone, shells and chalk. A common form of supplementary calcium in dogs and cats on meat-based diets, used because of its high concentration of calcium (40%) and absence of phosphorus.
calcium challenge test
an intravenous infusion of calcium will cause increased levels of gastrin in dogs with a gastrinoma. Often used in combination with a secretin test.
a salt used in solution to restore electrolyte balance, to treat hypocalcemia and as an antidote to magnesium poisoning. Is highly irritant and has been discarded generally in favor of less irritating substances, e.g. calcium borogluconate.
agricultural fertilizer capable of being toxic.
see calcium (above).
calcium edetate (Ca-EDTA)
calcium ethylenediamine tetra-acetic acid; the disodium and dipotassium salts are commonly used as anticoagulants in the preservation of blood samples for hematology. A chelating agent, used parenterally in the treatment of lead poisoning. See also edetate
in all species may cause hypercalcitonism
with decreased osteoclastic activity and skeletal remodeling. In dogs, disorders of enchondral ossification with curved radius and osteochondrosis have been demonstrated; secondary iron deficiency anemia occurs in piglets.
naturally occurring mineral. Called also fluorspar, fluorite.
contains high levels of calcium; given to cows as a drench or in the feed as a prophylaxis against milk fever.
a calcium replenisher and antidote to fluoride or oxalate poisoning.
maintenance of normal calcium metabolism by the combined effects of adequate alimentary intake, renal excretion, parathyroid hormone involvement, 1,25 dihydroxycholecalciferol (or calcitriol) and calcitonin, plasma protein binding and deposition in tissues.
an astringent compound used topically in solution or lotions; in dentistry used to encourage deposition of secondary dentine. Called also slaked lime. In solution, called lime water.
idiopathic calcium phosphate deposition
thought to be inherited as an autosomal dominant trait in Great Danes commencing in puppies about 5 weeks old, characterized by incoordination with deformity and displacement of the 7th cervical vertebra and mineral deposits in the intervertebral joints, in serous and synovial membranes and mineralization in most other tissues.
used for supplementing the diet with calcium; contains 18% calcium. As calcium sodium lactate, containing 8% calcium, it is more soluble and can be used in drinking water.
a calcium compound used parenterally in the treatment of hypocalcemia; contains 14.8% calcium.
administered orally and used as a urinary antiseptic.
used as an additive during cheese making to control fermentation. Whey from this cheese may cause nitrate poisoning in pigs.
protein-bound fractions of plasma calcium.
calcium nutritional deficiency
nutritional deficiency of calcium is rarely primary except in carnivores on an all-meat diet. Secondary deficiency is usually the result of diets having too high a content of phosphorus. The outcome of either deficiency may be nutritional hyperparathyroidism
in horse and pigs, and degenerative arthropathy
of cattle, depending on the species, age of the animal and availability of vitamin D. Hypocalcemia may not occur because of the activity of parathyroid hormone, but classical tetany and recumbency can occur if the deficiency is prolonged or if they are precipitated by some other factor.
a compound occurring in the urine in crystals and in certain calculi. See also oxalate urolith
alkaline and capable of causing gastroenteritis. There is a high concentration in basic
slag and this may contribute to that poisoning.
a calcium salt of the dextrorotatory isomer of pantothenic acid; used as a growth-promoting vitamin.
one of three salts containing calcium and the phosphate radical: dibasic and tribasic calcium phosphate are used as sources of calcium; monobasic calcium phosphate is used in fertilizer and as a calcium and phosphorus supplement. An important constituent of uroliths.
calcium : phosphorus ratio
the ratio of calcium to phosphorus in the diet, 1 : 1 to 1 : 2 is usually considered to be adequate for proper calcium nutritional status in most animal species. Diets outside this range are likely to cause osteodystrophies. Animals grazing phosphorus-deficient pasture, and those being intensively fed on grain rations which have an abnormally high phosphorus content, are the principal subjects. Horses on heavy grain diets and dogs and cats on meat diets without calcium supplementation are also targets for the disease.
a hydrophilic agent used as a bulk laxative in the treatment of constipation and diarrhea.
protein bound calcium
biologically inert fraction of plasma calcium; most is bound to albumin and globulins with a small fraction complexed to organic and inorganic acids.
crystals of this mineral are thought to contribute physically to the gastroenteritis caused by basic
the main component of plaster of Paris; also used as a dietary source of calcium and inorganic sulfate sulfur.
calcium sulfide, calcium polysulfide
include calcium carbonate, gluconate, lactate and phosphate; bone flour, bone meal, ground limestone, chalk.
calcium tungstate screens
cards coated with calcium tungstate crystals are used to sandwich film in a light-tight cassette. They fluoresce when exposed to x-rays and, together with the beam, affect the film emulsion. They reduce the exposure factor required.