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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.
cal·ci·um (Ca),, gen.
calciumA bivalent metallic element (atomic number 20; atomic weight 40.08) that is critical for bone and tooth formation and intimately linked to many metabolic processes, including muscle contraction, neural transmission, coagulation and inhibition of cell destruction. Calcium levels in the blood are controlled by the balanced action of parathyroid hormone and calcitonin. It is present in dairy products, almonds, leafy greens, sardines and salmon; proper absorption of calcium hinges on appropriate acidity of the stomach, presence of vitamin D and a balance of other minerals, including phosphorus and mangesium.
calciumA metal, atomic number 20, atomic weight 40.08, which is a divalent cation abundant in the body, especially in bone and teeth Calcium metabolism Ca2+ is the most critical mineral in bone–added by osteoblasts; removed by osteoclasts, Ca2+ maintains metabolic processes–eg, muscle contraction, neural transmission, cardiac activity, coagulation and inhibition of cell destruction; serum Ca2+ levels are controlled by a balance between PTH and calcitonin–produced by the thyroid's C or parafollicular cells; proper absorption of Ca2+ hinges on appropriate gastric acidity, presence of vitamin D, and a balance of other minerals–eg, phosphorus and mangesium; PTH ↑ serum Ca2+ levels by ↑ bone resorption via osteoclasts and mobilizing Ca2+, and indirectly ↑ GI absorption of Ca2+ by ↑ vitamin D production; PTH also ↑ phosphate excretion in the urine; calcitonin ↓ serum Ca2+ and phosphate levels by inhibiting bone resorption Daily requirement ± 400–1000 mg/day Ref range Infant to 1 month: 7.0-11.5 mg/dL; 1 month to 1 yr: 8.6-11.2 mg/dL >1 yr: 8.2-10.2 mg/dL; chronic abuse of laxatives, excess transfusions and various drugs can ↓ Ca2+ levels; Ca2+ is ↑ in hyperparathyroidism, parathyroid tumors, Paget's disease, myeloma, metastatic CA, multiple Fx, prolonged immobilization, renal disease, adrenal insufficiency, ↑ Ca2+ ingestion, antacid abuse; Ca2+ is ↓ in Cushing syndrome, hypoparathyroidism, malabsorption, acute pancreatitis, renal failure, peritonitis. See Hypercalcemia, Hypocalcemia, Ionized calcium.
calcium(kal'se-um) [ calci- + -ium] Ca
Calcium is important for blood clotting, enzyme activation, and acid-base balance. It gives firmness and rigidity to bones and teeth. It is essential for lactation, the function of nerves and muscles (including heart muscle), and maintenance of membrane permeability. Most absorption of calcium occurs in the duodenum and is dependent on the presence of calcitriol. Dietary factors affecting calcium absorption include phytic acid, consumption of too much phosphorus, and polyphenols found in tea. Approximately 40% of the calcium consumed is absorbed. Blood levels of calcium are regulated by parathyroid hormone; deficiency of this hormone produces hypocalcemia. The serum level of calcium is normally about 8.5 to 10.5 mg/dl. Low blood calcium causes tetany. Blood deprived of its calcium will not clot. Calcium is deposited in the bones but can be mobilized from them to keep the blood level constant when dietary intake is inadequate. At any given time, the body of an adult contains about 700 g of calcium phosphate; of this, 120 g is the element calcium. Adults should consume at least 1 g of calcium daily. Pregnant, lactating, and postmenopausal women should consume 1.2–1.5 g of calcium per day.
Excellent sources of calcium include milk and milk products (but not cottage cheese), and calcium-fortified orange juice. Good sources include canned salmon and sardines, broccoli, tofu, rhubarb, almonds, figs, and turnip greens.
CAUTION!1. Laboratory error and variation may sometimes cause inaccurate or inconsistent values in evaluating calcium levels.
CAUTION!2. Excessive calcium supplementation has been associated with a small increased risk of vascular calcification and heart attack.
calcium disodium edetate
total serum calcium
calciumA mineral present in large quantity in the body, mainly in the form of calcium phosphate in the bones and the teeth. Electrically charged calcium atoms (ions) are present in the blood and body fluids and are essential for many physiological processes including cell membrane permeability, cell excitability, the initiation and transmission of electrical impulses, muscle contraction, cell shape and cell motility. Calcium is necessary for blood coagulation, the production of ATP, and enzyme actions. Calcium levels in the blood are kept withing narrow limits by feedback mechanisms. Brand names of preparations containing calcium used to treat OSTEOPOROSIS are Ostram and Sandocal.
calcium (Ca)an essential element to all animals and plants and a constituent of shells, bones and teeth.
Patient discussion about calcium
Q. It will be fine for my dad to take calcium as extra supplement; It will be fine for my dad to take calcium as extra supplement; as his bones are getting weak…. How much calcium intake is necessary for him?
Q. My sister has been having major allergy problems.How could she get her desired calcium? My sister has been having major allergy problems. Now she has developed an allergy and cannot tolerate milk in any form. None of our family members had allergic reactions to milk and my sister very recently developed this symptom. Is there any possibility of this symptom linked with any other illness? How could she get her desired calcium intake required by the body? Can you make any suggestions please?
many good sources of calcium exist. These include seaweeds such as kelp, wakame . nuts and seeds (like almonds and sesame). blackstrap molasses, beans, oranges, figs, quinoa , broccoli...
and another thing that you may do is crush an egg shell into powder and just mix a bit with her food. it's an excellent source.
Q. I'm concerned that my calcium supplements are contaminated w seashells or cow bones. Which brands are best
here is something that helped me choose: