Total calcium in the body is 100-170 grams, 99% is found in bones, existing as Calcium carbonate or Calcium phosphate.
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Normal serum calcium level : 9-11 mg/dl.
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Blood calcium level is controlled by the parathyroid glands.
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Daily dietary calcium intake :
- Newborn infants : 360 mg.
- Children and Adults : 800 mg.
- Adolescents, Pregnant and Lactacting women increases by 50% (1,200mg).
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Renal threshold for calcium : 7 mg/dl of serum calcium.
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Normal daily urinary calcium excretion : 250-300 mg.
Hypocalcemia
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Serum calcium less than 8.5 mg/dl.
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Causes :
- Hypoalbuminemia
- Renal failure.
- Surgically induced hypoparathyroidism.
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Leads to hyperirritability and tetany (Carpopedal spasm, Laryngospasm, Convulsions).
Hypercalcemia
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Serum calcium more than 11 mg/dl.
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Causes :
- Primary hyperparathyroidism.
- Malignancy.
- Acute adrenal insufficiency.
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Leads to decreased nerve conductivity and muscle rigor.
Pathologic Calcification
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Abnormal deposition of calcium salts with small amount of iron, magnesium and other minerals.
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Classified as Dystrophic calcification, Metastatic calcification, and Calcinosis.
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Dystrophic Calcification : Calcium salts are deposited in dead or degenerating tissues eg. areas of tubular necrosis, blood vessels in arteriosclerosis, scars, areas of fatty degeneration, mouth / gingiva, tongue, cheeks, benign fibromas, dental pulp (in older persons).
- Local alkalinity is important in initiating the precipitation of calcium.
- Not dependent on increased circulating blood calcium levels.
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Metastatic Calcification : Calcium salts are precipitated in previously undamaged tissues due to an excess blood calcium levels.
- Seen in diseases such as hyperparathyroidism, hypervitaminosis D.
- Occurs mainly in kidneys, lungs, gastric mucosa and blood vessel media.
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Calcinosis : Presence of calcification in / under the skin.
- Two forms : Calcinosis circumscripta (circumscribed form) and Calcinosis universalis (generalised form, associated with scleroderma).
Points to Note
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Macrominerals : Daily requirement more than 100mg. Includes :
- Sodium, Potassium, Chlorine, Calcium, Phosphorus, Magnesium and Sulfur.
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Microminerals : Daily requirement less than 100 mg and present in less thna 0.005% body weight. Includes :
- Chromium, Copper, Cobalt, Iron, Iodine, Manganese, Selenium, Flourine and Zinc.
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Calcium in the plasma is of three types : Ionised Calcium (physiologically active form), Protein-bound calcium, Complexed calcium.
References
- Shafer, Hine, Levy Shafer's Textbook of Oral Pathology (7th Edition), Editors - R Rajendran, B Sivapathasundharam, Elsevier.
*This article is an excerpt from the above mentioned books and Medical Sutras does not make any ownership or affiliation claims.