vitamin K deficiency

Vitamin K Deficiency

Definition

Vitamin K deficiency exists when chronic failure to eat sufficient amounts of vitamin K results in a tendency for spontaneous bleeding or in prolonged and excessive bleeding with trauma or injury. Vitamin K deficiency occurs also in newborn infants, as well as in people treated with certain antibiotics. The protein in the body most affected by vitamin K deficiency is a blood-clotting protein called prothrombin.

Description

Vitamin K is a fat-soluble vitamin. The recommended dietary allowance (RDA) for vitamin K is 80 mg/day for the adult man, 65 mg/day for the adult woman, and 5 mg/day for the newborn infant. The vitamin K present in plant foods is called phylloquinone; while the form of the vitamin present in animal foods is called menaquinone. Both of these vitamins are absorbed from the diet and converted to an active form called dihydrovitamin K.Spinach, lettuce, broccoli, brussels sprouts, and cabbage are good sources of vitamin K, containing about 8 mg vitamin K/kg food. Cow milk is also a good source of the vitamin.A portion of the body's vitamin K is supplied by bacteria living in the intestine rather than by dietary sources.Vitamin K plays an important role in blood clotting. Without the vitamin, even a small cut would cause continuous bleeding in the body, and death. Blood clotting is a process that begins automatically when any injury produces a tear in a blood vessel. The process of blood clotting involves a collection of molecules, which circulate continuously through the blood-stream. When an injury occurs, these molecules rapidly assemble and form the blood clot. The clotting factors are proteins, and include proteins called Factor II, Factor VII, Factor IX, and Factor X. Factor II is also called prothrombin. These proteins require vitamin K for their synthesis in the body. The blood-clotting process also requires a dozen other proteins that do not need vitamin K for their synthesis.

Causes and symptoms

Newborns are especially prone to vitamin K deficiency. A nursing-mother's milk is low in the vitamin; breast milk can supply only about 20% of the infant's requirement. Infants are born with low levels of vitamin K in their body; they do not have any vitamin K-producing bacteria in their intestines. Their digestive tracts are sterile. As a result, a form of vitamin K deficiency, called hemorrhagic disease of the newborn, may develop. This disease involves spontaneous bleeding beneath the skin or elsewhere in the infant's body, and occurs in about 1% of all infants. In rare cases, it causes death due to spontaneous bleeding in the brain.Vitamin K deficiency in adults is rare. When it occurs, it is found in people with diseases that prevent the absorption of fat. These diseases include cystic fibrosis, celiac disease, and cholestasis. Vitamin K deficiency can exist in adults treated with antibiotics that kill the bacteria that normally live in the digestive tract. As mentioned, the intestine-bacteria supply part of our daily requirement of vitamin K. Vitamin K deficiency can result in bleeding gums, and in skin that is easily bruised.Others who may benefit from supplemental vitamin K include those taking medications that interact with it or deplete the supply. It also appears to have some effectiveness in preventing osteoporosis, but some studies done involved patients using a high dietary intake of the vitamin rather than supplements. In 2003, however, a group of Japanese researchers reported that supplemental doses of vitamin K₂ given together with vitamin D₃ appeared to reduce bone turnover and sustain bone density in postmenopausal women with mild osteoporosis.Chronically low levels of vitamin K are correlated with higher risk of hip fracture in older men and women. A study done in 2003 reported that the current recommended dietary intake for vitamin K in adults may not be adequate for older women.

Diagnosis

Vitamin K status is measured by the prothrombin time test. The normal prothrombin time is about 13 seconds. With vitamin K deficiency, the prothrombin time can be several minutes. The test involves taking a sample of blood, placing it in a machine called a fibrometer, and measuring the time it takes for blood-clot formation. Blood-clotting problems can also be caused by a rare genetic disease called hemophilia. Hemophilia is not related to vitamin K deficiency. Once vitamin K deficiency is suspected, further tests must be used to distinguish it from possible hemophilia. Where a bleeding disorder can be corrected by vitamin K treatment, the diagnosis of vitamin K deficiency is proven to be correct.

Treatment

Vitamin K deficiency in newborn infants is treated and prevented with a single injection of phylloquinone (5 mg). Adults with vitamin K deficiency are treated with daily oral doses of 10 mg phylloquinone for one week.

Prognosis

The prognosis for correcting vitamin K deficiency, and associated blood-clotting problems, is excellent.

Key terms

Fat-soluble vitamin — Fat-soluble vitamins can be dissolved in oil or in melted fat.Hemorrhage — Bleeding that continues for an abnormally long period of time.Phylloquinone — An alternate name for vitamin K₁.Prothrombin — Prothrombin is a blood-clotting protein. Injury to a blood vessel produces a signal which triggers the conversion of prothrombin to thrombin. Thrombin is a protein which plays a central role in provoking the assembly of other proteins to form the blood clot.Recommended Dietary Allowance (RDA) — The Recommended Dietary Allowances (RDAs) are quantities of nutrients in the diet that are required to maintain good health in people. RDAs are established by the Food and Nutrition Board of the National Academy of Sciences, and may be revised every few years. A separate RDA value exists for each nutrient. The RDA values refer to the amount of nutrient expected to maintain good health in people. The actual amounts of each nutrient required to maintain good health in specific individuals differ from person to person.Water-soluble vitamins — Water-soluble vitamins can be dissolved in water or juice.

Prevention

Aside from newborns and young infants, vitamin K deficiency is not a concern for the general population. Vitamin K deficiency can be prevented by assuring that the diet contains such foods as spinach, cabbage, brussels sprouts, and eggs. Soybean oil, canola oil, and olive oil are good sources of the vitamin, while corn oil and peanut oil are very poor sources. Elderly people, especially those living alone, should be checked for adequate intake of the vitamin.

Resources

Books

Pelletier, Kenneth R., MD. The Best Alternative Medicine, Part I: Food for Thought. New York: Simon & Schuster, 2002.

Periodicals

American Academy of Pediatrics Committee on Fetus and Newborn. "Controversies Concerning Vitamin K and the Newborn. American Academy of Pediatrics Committee on Fetus and Newborn." Pediatrics 112, no. 1, Part 1 (July 2003): 191-192.Booth, S. L., L. Martini, J. W. Peterson, et al. "Dietary Phylloquinone Depletion and Repletion in Older Women." Journal of Nutrition 133 (August 2003): 2565-2569.Iwamoto, J., T. Takeda, and S. Ichimura. "Treatment with Vitamin D₃ and/or Vitamin K₂ for Postmenopausal Osteoporosis." Keio Journal of Medicine 52 (September 2003): 147-150.

Organizations

American Academy of Pediatrics (AAP). 141 Northwest Point Boulevard, Elk Grove Village, IL 60007. (847) 434-4000. http://www.aap.org.American Society for Clinical Nutrition. 9650 Rockville Pike, Bethesda, MD 20814. (301) 530-7110. http://www.faseb.org/ascn.

vitamin K deficiency

A condition caused by a paucity of vitamin K1 and/or K2, which is extremely rare, given that most vitamin K is produced in the large intestine by bacterial flora.
Aetiology
Impaired intestinal uptake (as occurs in a bile duct obstruction); ingestion of vitamin K antagonist.
Clinical findings
Birth defects (e.g., underdeveloped face, bones, digits), bleeding, haematomas, possible massive bleeding, oozing of blood at surgical or puncture sites, stomach pains, deposition of calcium salts in arterial walls.

vitamin K deficiency

A rare condition–most vitamin K is produced in the large intestine by bacterial flora; it may occur in infants with inadequate intestinal bacteria and result in clotting defects. See Vitamin K.

单词	vitamin k deficiency
释义	DictionarySeevitamin K vitamin K deficiency Vitamin K Deficiency Definition Vitamin K deficiency exists when chronic failure to eat sufficient amounts of vitamin K results in a tendency for spontaneous bleeding or in prolonged and excessive bleeding with trauma or injury. Vitamin K deficiency occurs also in newborn infants, as well as in people treated with certain antibiotics. The protein in the body most affected by vitamin K deficiency is a blood-clotting protein called prothrombin. Description Vitamin K is a fat-soluble vitamin. The recommended dietary allowance (RDA) for vitamin K is 80 mg/day for the adult man, 65 mg/day for the adult woman, and 5 mg/day for the newborn infant. The vitamin K present in plant foods is called phylloquinone; while the form of the vitamin present in animal foods is called menaquinone. Both of these vitamins are absorbed from the diet and converted to an active form called dihydrovitamin K.Spinach, lettuce, broccoli, brussels sprouts, and cabbage are good sources of vitamin K, containing about 8 mg vitamin K/kg food. Cow milk is also a good source of the vitamin.A portion of the body's vitamin K is supplied by bacteria living in the intestine rather than by dietary sources.Vitamin K plays an important role in blood clotting. Without the vitamin, even a small cut would cause continuous bleeding in the body, and death. Blood clotting is a process that begins automatically when any injury produces a tear in a blood vessel. The process of blood clotting involves a collection of molecules, which circulate continuously through the blood-stream. When an injury occurs, these molecules rapidly assemble and form the blood clot. The clotting factors are proteins, and include proteins called Factor II, Factor VII, Factor IX, and Factor X. Factor II is also called prothrombin. These proteins require vitamin K for their synthesis in the body. The blood-clotting process also requires a dozen other proteins that do not need vitamin K for their synthesis. Causes and symptoms Newborns are especially prone to vitamin K deficiency. A nursing-mother's milk is low in the vitamin; breast milk can supply only about 20% of the infant's requirement. Infants are born with low levels of vitamin K in their body; they do not have any vitamin K-producing bacteria in their intestines. Their digestive tracts are sterile. As a result, a form of vitamin K deficiency, called hemorrhagic disease of the newborn, may develop. This disease involves spontaneous bleeding beneath the skin or elsewhere in the infant's body, and occurs in about 1% of all infants. In rare cases, it causes death due to spontaneous bleeding in the brain.Vitamin K deficiency in adults is rare. When it occurs, it is found in people with diseases that prevent the absorption of fat. These diseases include cystic fibrosis, celiac disease, and cholestasis. Vitamin K deficiency can exist in adults treated with antibiotics that kill the bacteria that normally live in the digestive tract. As mentioned, the intestine-bacteria supply part of our daily requirement of vitamin K. Vitamin K deficiency can result in bleeding gums, and in skin that is easily bruised.Others who may benefit from supplemental vitamin K include those taking medications that interact with it or deplete the supply. It also appears to have some effectiveness in preventing osteoporosis, but some studies done involved patients using a high dietary intake of the vitamin rather than supplements. In 2003, however, a group of Japanese researchers reported that supplemental doses of vitamin K₂ given together with vitamin D₃ appeared to reduce bone turnover and sustain bone density in postmenopausal women with mild osteoporosis.Chronically low levels of vitamin K are correlated with higher risk of hip fracture in older men and women. A study done in 2003 reported that the current recommended dietary intake for vitamin K in adults may not be adequate for older women. Diagnosis Vitamin K status is measured by the prothrombin time test. The normal prothrombin time is about 13 seconds. With vitamin K deficiency, the prothrombin time can be several minutes. The test involves taking a sample of blood, placing it in a machine called a fibrometer, and measuring the time it takes for blood-clot formation. Blood-clotting problems can also be caused by a rare genetic disease called hemophilia. Hemophilia is not related to vitamin K deficiency. Once vitamin K deficiency is suspected, further tests must be used to distinguish it from possible hemophilia. Where a bleeding disorder can be corrected by vitamin K treatment, the diagnosis of vitamin K deficiency is proven to be correct. Treatment Vitamin K deficiency in newborn infants is treated and prevented with a single injection of phylloquinone (5 mg). Adults with vitamin K deficiency are treated with daily oral doses of 10 mg phylloquinone for one week. Prognosis The prognosis for correcting vitamin K deficiency, and associated blood-clotting problems, is excellent. Key terms Fat-soluble vitamin — Fat-soluble vitamins can be dissolved in oil or in melted fat.Hemorrhage — Bleeding that continues for an abnormally long period of time.Phylloquinone — An alternate name for vitamin K₁.Prothrombin — Prothrombin is a blood-clotting protein. Injury to a blood vessel produces a signal which triggers the conversion of prothrombin to thrombin. Thrombin is a protein which plays a central role in provoking the assembly of other proteins to form the blood clot.Recommended Dietary Allowance (RDA) — The Recommended Dietary Allowances (RDAs) are quantities of nutrients in the diet that are required to maintain good health in people. RDAs are established by the Food and Nutrition Board of the National Academy of Sciences, and may be revised every few years. A separate RDA value exists for each nutrient. The RDA values refer to the amount of nutrient expected to maintain good health in people. The actual amounts of each nutrient required to maintain good health in specific individuals differ from person to person.Water-soluble vitamins — Water-soluble vitamins can be dissolved in water or juice. Prevention Aside from newborns and young infants, vitamin K deficiency is not a concern for the general population. Vitamin K deficiency can be prevented by assuring that the diet contains such foods as spinach, cabbage, brussels sprouts, and eggs. Soybean oil, canola oil, and olive oil are good sources of the vitamin, while corn oil and peanut oil are very poor sources. Elderly people, especially those living alone, should be checked for adequate intake of the vitamin. Resources Books Pelletier, Kenneth R., MD. The Best Alternative Medicine, Part I: Food for Thought. New York: Simon & Schuster, 2002. Periodicals American Academy of Pediatrics Committee on Fetus and Newborn. "Controversies Concerning Vitamin K and the Newborn. American Academy of Pediatrics Committee on Fetus and Newborn." Pediatrics 112, no. 1, Part 1 (July 2003): 191-192.Booth, S. L., L. Martini, J. W. Peterson, et al. "Dietary Phylloquinone Depletion and Repletion in Older Women." Journal of Nutrition 133 (August 2003): 2565-2569.Iwamoto, J., T. Takeda, and S. Ichimura. "Treatment with Vitamin D₃ and/or Vitamin K₂ for Postmenopausal Osteoporosis." Keio Journal of Medicine 52 (September 2003): 147-150. Organizations American Academy of Pediatrics (AAP). 141 Northwest Point Boulevard, Elk Grove Village, IL 60007. (847) 434-4000. http://www.aap.org.American Society for Clinical Nutrition. 9650 Rockville Pike, Bethesda, MD 20814. (301) 530-7110. http://www.faseb.org/ascn. vitamin K deficiency A condition caused by a paucity of vitamin K1 and/or K2, which is extremely rare, given that most vitamin K is produced in the large intestine by bacterial flora. Aetiology Impaired intestinal uptake (as occurs in a bile duct obstruction); ingestion of vitamin K antagonist. Clinical findings Birth defects (e.g., underdeveloped face, bones, digits), bleeding, haematomas, possible massive bleeding, oozing of blood at surgical or puncture sites, stomach pains, deposition of calcium salts in arterial walls. vitamin K deficiency A rare condition–most vitamin K is produced in the large intestine by bacterial flora; it may occur in infants with inadequate intestinal bacteria and result in clotting defects. See Vitamin K. AcronymsSeeVKD
随便看	zinc plated zinc plated steel zinc-plating zinc poisoning zinc polycarbonate cement zinc polycarboxylate cement zinc primary battery zinc processing zinc proto-porphyrin zinc protoporphyrin zinc pyrithione zinc-regulated gene zinc regulatory factor zinc residue zinc resistor zinc-responsive dermatoses zinc-responsive dermatosis zinc rich paint zinc rich primers zinc ring finger protein sag zincs zinc salt zinc selenide zinc silicate zinc-silver chloride primary cell