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Encyclopedia > Calcitriol

Vitamin D is a fat soluble vitamin that contributes to the maintenance of normal levels of calcium and phosphorus in the bloodstream. Vitamins are organic chemicals that a given living organism requires in trace quantities for good health, but which the organism cannot synthesize, and therefore must obtain from its diet. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ... This article is about the chemical element. ...


Often known as calciferol.


Forms of Vitamin D:

  • Vitamin D1: lamisterol
  • Vitamin D2: ergocalciferol (made from ergosterol)
  • Vitamin D3: cholecalciferol (made from 7-dehydrocholesterol)
  • Vitamin D4: dihydrotachysterol (22:23-dihydrovitamin D2)
  • Vitamin D5: irridated 7-dehydrositosterol

Contents

Ergocalciferol is a form of Vitamin D with the systematic name (5Z,7E,22E)-(3S)-9,10-seco-5,7,10(19),22-ergostatetraen-3-ol. ... Ergosterol is the biological precursor to Vitamin D2. ... Cholecalciferol is a form of Vitamin D. Vitamin D3 is also a steroid much like testosterone, cholesterol and cortisol. ...


Vitamin D, sunlight and skin color

There are several forms of the vitamin. Jake eats them all. Vitamin D2 is derived from ergosterol in the diet, whereas vitamin D3 is derived from cholesterol via 7-dehydrocholesterol. Ultraviolet light (UVB especially from sunlight is responsible for the production of the vitamin- 50,000 IU in a few minutes of exposure.) However, in certain parts of the world with limited sunlight there is the possibility that the quantity of vitamin D is not always sufficient. To prevent this possibility, milk may be fortified with vitamin D2. A deficiency of vitamin D leads to rickets which is a softening of the bones owing to faulty mineralization. Ergosterol is the biological precursor to Vitamin D2. ... Cholesterol is a steroid lipid, found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. ... In the skin 7-dehydrocholesterol (sometimes known as provitamin D3) is synthesized from cholesterol. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... A glass of cows milk Milk most often means the nutrient fluid produced by the mammary glands of female mammals. ... X-ray of the legs in a two-year-old child with rickets Rickets is a disorder of infancy and early childhood of multiple etiologies. ...


The active form of the vitamin is calcitriol which is synthesized from either D2 or D3 in the kidneys. Calcitriol binds to a protein transcription factor which then regulates gene expression. The outcome is the maintenance of calcium and phosphorus levels in the bone and blood with the assistance of parathyroid hormone and calcitonin. Kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ... This article is about the chemical element. ... Grays illustration of a human femur, a typically recognized bone. ... Red blood cells (erythrocytes) are present in the blood and help carry oxygen to the rest of the cells in the body Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). ... Parathyroid hormone (PTH) is secreted by the parathyroid glands as a polypeptide containing 84 amino acids. ... textCalcitonin is a a 32 amino acid polypeptide hormone that is produced in humans primarily by the C cells of the thyroid. ...


Pioneering work in isolating vitamin D and determining its role in rickets was done by Edward Mellanby in 1918-1920. Professor Edward Mellanby (1884 - 1955) discovered vitamin D and the role of the vitamin in preventing rickets in 1919. ... 1918 was a common year starting on Tuesday (see link for calendar). ... 1920 is a leap year starting on Thursday (link will take you to calendar) // Events January January 7 - Forces of Russian White admiral Kolchak surrender in Krasnoyarsk. ...


Vitamin D deficiency is also known to cause:

  • Osteoporosis: A condition characterized by fragile bones.
  • Osteomalacia: A bone-thinning disorder in adults that is similar to rickets.

Vitamin D malnutrition may also be linked to chronic diseases such as cancer (breast, ovarian, colon, prostate, lung and skin), chronic pain, weakness, chronic fatigue, autoimmune diseases like multiple sclerosis and Type 1 diabetes, high blood pressure, mental illnesses (depression, seasonal affective disorder and possibly schizophrenia) heart disease, rheumatoid arthritis, psoriasis, tuberculosis, periodontal disease and inflammatory bowel disease. Osteoporosis is a disease of bone in which the amount of bone is decreased and the strength of trabecular bone is reduced, cortical bone becomes thin and bones are susceptible to fracture. ... Osteomalacia is a disease characterized clinically by a painful softening of the bones. ... When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ... Breast cancer is cancer of breast tissue. ... Ovarian cancer is a malignant ovarian neoplasm (an abnormal growth located on the ovaries). ... Diagram of the stomach, colon, and rectum Colorectal cancer includes cancerous growths in the colon, rectum and appendix. ... Prostate cancer is a group of cancerous cells (a malignant tumor) that begins most often in the outer part of the prostate. ... The incidence of lung cancer is highly correlated with smoking. ... In medicine (dermatology), there are several different types of cancer referred to under the general label of skin cancer. ... This article is about the disease that features high blood sugar. ... Hypertension or high blood pressure is a medical condition where the blood pressure in the arteries is chronically elevated. ... Clinical depression is a health condition of depression with mental and physical components reaching criteria generally accepted by clinicians. ... Seasonal affective disorder, or SAD, is an affective, or mood disorder. ... There are different forms of heart disease: Coronary heart disease Ischaemic heart disease Cardiovascular disease The study of heart disease is Cardiology This is a disambiguation page — a navigational aid which lists pages that might otherwise share the same title. ... Rheumatoid arthritis (RA) is a chronic, inflammatory autoimmune disorder that causes the immune system to attack the joints. ... Tuberculous lungs show up on an X-ray image Tuberculosis is an infection with the bacterium Mycobacterium tuberculosis, which most commonly affects the lungs (pulmonary TB) but can also affect the central nervous system (meningitis), lymphatic system, circulatory system (miliary TB), genitourinary system, bones and joints. ...


Who may need extra vitamin D to prevent a deficiency?

Older people (greater than age 50) are thought to have a higher risk of developing vitamin D deficiency. The ability of skin to convert vitamin D to its active form decreases as we age. The kidneys, which help convert vitamin D to its active form, sometimes do not work as well when people age. Therefore, some older people may need vitamin D from a supplement. Kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ...


Newborn infants who are exclusively breastfed may require vitamin D supplements. Breast milk does not contain significant levels of the vitamin, and although infants could receive this vitamin from sunlight, it is usually not recommended that small infants be exposed to sunlight in the levels required to produce a sufficient amount of vitamin D. Infant formula is generally fortified with vitamin D, so this requirement only applies to breastfed infants. A breastfeeding infant Breastfeeding is the practice of a woman feeding an infant (or sometimes a toddler or a young child) with milk produced from her mammary glands, usually directly from the nipples. ... Breast milk usually refers to the milk produced by a human female which is usually fed to infants by breastfeeding. ... An infant being fed by bottle. ...


Those who avoid or are not exposed to the midday sunshine may also require Vitamin D supplements. In particular, recent studies have shown Australians and New Zealanders are Vitamin D deficient [1], particularly after the successful "Slip-Slop-Slap" health campaign encouraging Australians to cover up when exposed to sunlight to prevent skin cancer. Ironically, a vitamin D deficiency too may lead to skin cancer. Sunlight is also the trade name of the worlds first packaged, branded laundry soap producted by Lever Brothers. ... Slip-Slop-Slap is the name for a health campaign in Australia exhorting people to slip on a shirt, slop on sunscreen, and slap on a hat when they go out into the sun in order to prevent skin cancer. ... In medicine (dermatology), there are several different types of cancer referred to under the general label of skin cancer. ...


Recent research suggests that human beings can metabolise about 5,000 international units (IU) per day, although the metabolic pathways have not yet been identified. Given this, and given that humans on vitamin pills of 200 IU per day become deficient if not exposed to sunlight there is reasonably convincing evidence that the Recommended Dietary Allowance (RDA) may be very much too small. The fact that human skin produces such large quantities as 50,000 IU without any apparent toxicity also gives strong support for this position. An International unit (IU) is a unit of measurement in pharmacology. ... Recommended Dietary Allowance (RDA) is the daily dietary intake level of a nutrient that is considered sufficient to meet the requirements of nearly all (97-98%) healthy individuals in each life-stage and gender group. ...


In addition, merely being exposed to sunlight does not guarantee that vitamin D is produced, only the UVB in sunlight triggers vitamin D3 production; UVB only reaches ground level when the sun is very high in the sky. At many lattitudes this only occurs in the summertime close to solar midday (1 pm summertime). In the US, those living above a line from San Francisco to Atlanta will not be able to produce it at all for 3 to 6 months a year. US,Us or us may stand for the United States of America us, the oblique case form of the English language pronoun we. ... This article is about the city in California. ... This article is about the state capital of Georgia. ...


Only a few minutes of exposure is all that is required; the production is very rapid.


Oral overdose of vitamin D3

Overdose is extremely rare whilst mild deficiencies are very common.


For overdose to occur chronic doses of 100x the standard RDA each day, over many months is normally required. The RDA itself is in fact more than 200x less than the amount that may be generated in even a few minutes of midday sunshine. But whilst the sunshine generated quantity is self-limiting, vitamin pills are not and this has led to widespread concern, which may have been very much misplaced.


In practice, all common foods and correctly formulated vitamin pills essentially contain far too little for overdose to ever occur in normal circumstances. Indeed, Stoss therapy involves taking a dose over a thousand times the daily RDA once every few months and even then often fails to normalise vitamin D3 levels in the body.


However, oral overdose has been recorded due to manufacturing and industrial accidents and leads to hypercalcemia and atheroschlerosis, so overdose is very definitely possible.


Vitamin D and cancer recovery

Recent research suggests that cancer patients who have their surgery/treatment in the summer - and therefore get more vitamin D - have a much better chance of surviving the disease than those who have their treatment in the winter when they are exposed to less sunlight.[2]


Vitamin D food sources

Fortified foods are the major dietary sources of vitamin D. Prior to the fortification of milk products in the 1930s, rickets was a major public health problem. In the United States milk is fortified with 10 micrograms (400 IU) of vitamin D per quart, and rickets is now uncommon in the US . An International unit (IU) is a unit of measurement in pharmacology. ... A quart is a unit of measurement for volume. ...


One cup of vitamin D fortified milk supplies about one-fourth of the estimated daily need for this vitamin for adults. Although milk is fortified with vitamin D, dairy products made from milk such as cheese, yogurt, and ice cream are generally not fortified with vitamin D. Only a few foods naturally contain significant amounts of vitamin D, including: Cup can refer to: A drinking vessel such as a teacup or similar drinkware. ...

  • fatty fish such as salmon, cooked, 3.5 oz, 360 IU;
  • mackerel, cooked, 3.5 oz, 345 IU;
  • sardines, canned in oil, drained, 3.5 oz, 270 IU;
  • eel, cooked, 3.5 oz, 200 IU;
  • fish oils such as cod liver oil, 1 Tbs., 1,360 IU; and
  • egg yolk (one whole yolk, 25 IU).

Sources: National Institutes of Health, National Osteoporosis Society The Chinook or King Salmon is the largest salmon in North America and can grow up to 58 long and 126 pounds. ... The ounce is the name for a number of different units of mass (oz), and also of two units of fluid volume (fl oz) and of one unit of force, the ounce-force (ozf). ... Mackerel is a common name applied to a number of different species of fish, mostly, but not exclusively, from the family Scombridae. ... Sardines or pilchards are a group of several types of small oily fish related to herrings, family Clupeidae. ... Families Many; see text An eel is any of the fishes in the order Anguilliformes. ... Cod liver oil is an oil extracted from cod livers. ... The National Institutes of Health is an institution of the United States government which focuses on medical research. ...


Synthesis

Vitamin D3

Vitamin D3 is synthesized from 7-dehydrocholesterol, a derivative of cholesterol, which is then photolyzed by ultraviolet light. The product is Previtamin D3. Image:Reaction-Dehydrocholesterol-PrevitaminD3.png Cholesterol is a steroid lipid, found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... Wikipedia does not have an article with this exact name. ...


Previtamin D3 then spontaneously isomerizes to Vitamin D3 Image:Reaction-PrevitaminD3-VitaminD3.png Wikipedia does not have an article with this exact name. ...


Vitamin D3 (cholecalciferol) is then converted to calcitriol (1,25-dihydroxycholecalciferol) by the enzyme calcidiol 1-monooxygenase: Image:Reaction-VitaminiD3-Calcitriol.png Wikipedia does not have an article with this exact name. ...


External links

  • Medical Encyclopedia article (note: not a public domain resource)
  • Food Sources of Vitamin D.
  • How much Vitamin D is too much? Half of the world seem to be deficient...
  • Vitamin D information

  Results from FactBites:
 
Calcitriol - Wikipedia, the free encyclopedia (211 words)
It is produced in the kidneys by conversion from 25-hydroxycholecalciferol (calcidiol) and regulates calcium levels by increasing the absorption of calcium from the gastrointestinal tract.
Calcitriol is also commonly used as a medication in the treament of hypocalcaemia and osteoporosis.
Calcitriol is also sometimes used topically in the treament of psoriasis, however the evidence to support its efficacy is inconclusive.
Calcitriol (1148 words)
Calcitriol and 1,25 dihydroxycholecalciferol are both scientific names for active vitamin D. The biochemistry of vitamin D is very different from that of other vitamins; vitamin D is actually a hormone.
To understand how calcitriol is helpful in the treatment of chronic renal failure, it is helpful to understand some background infromation about vitamin D, its metabolic opposite “Parathyroid hormone,” and the general calcium and phosphorus balance within the body.
Calcitriol is able to elevate serum calcium in some cases which can further destabilize the calcium phosphorus balance and can create further toxicity issues to the kidney.
  More results at FactBites »

 
 

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