/rik"its/, n. Pathol.a disease of childhood, characterized by softening of the bones as a result of inadequate intake of vitamin D and insufficient exposure to sunlight, also associated with impaired calcium and phosphorus metabolism.[1635-45; orig. uncert.]
* * *or vitamin D deficiencyCalcium phosphate is not properly deposited in the bones, which become soft, curved, and stunted. Early symptoms include restlessness, profuse sweating, lack of limb and abdominal-muscle tone, soft skull bones, and developmental delays. Muscles may cramp and twitch. Without early treatment, effects may include bowlegs, knock-knees, and beadiness where the ribs meet the breastbone. A narrow chest and pelvis can later increase susceptibility to lung diseases and impede childbirth. Treatment is with high-dose vitamin D supplementation, sunlight, and a balanced diet. Adding vitamin D to milk has reduced rickets in high-latitude areas where the skin cannot produce enough.
* * *disease of infancy and childhood characterized by defective bone growth and caused by a lack of vitamin D in the body.Vitamin D is a steroid that is produced in the skin by the action of sunlight's ultraviolet (ultraviolet radiation) rays on its precursor, 7-dehydrocholesterol (provitamin D3). Vitamin D is also absorbed from the diet, especially from fortified milk, liver, and fish oils. Vitamin D deficiency can result from a lack of the vitamin in the diet, insufficient conversion in the skin by ultraviolet light, inefficient dietary absorption, or the abnormal conversion of vitamin D to its metabolites.Vitamin D is transported through the blood to the liver, where it serves as the precursor for a hormone whose primary target tissues are the small intestine, bone, and kidney, where it helps regulate the level of calcium in those tissues. Because vitamin D plays an important role in the metabolism of calcium, in its absence the deposition in the bones of the inorganic salt calcium phosphate (responsible for bone rigidity) does not proceed normally, and the softened bones become curved and stunted. Unless treatment is begun early, rickets may produce such conditions as bowlegs, knock-knees, and a beady appearance of the ribs (“rachitic rosary”) at their juncture to the breastbone. A narrowed chest and pelvis may be responsible later in life for increased susceptibility to lung diseases and difficulties in childbearing.Common early symptoms of rickets include restlessness, profuse sweating, lack of muscle tone in the limbs and abdomen, softening of the bones of the skull, delay in learning to sit, crawl, and walk, and delay in the eruption of the teeth. tetany (spasms of the hands and feet and cramps and twitching of the muscles) may also occur. Rickets is usually effectively treated with large supplemental doses of vitamin D concentrates, with exposure to sunlight, and with a well-balanced diet. Vitamin D supplement, usually with milk, has been important in preventing the incidence of rickets in the northern and temperate climates.The therapeutic effects of cod-liver oil and of sunlight in preventing and curing rickets in humans was recognized in the 18th century, although these treatments were generally accepted only in the early 1900s. The existence of a vitamin responsible for the effects of cod-liver oil was indicated in experimental animals in 1918. In 1924 it was demonstrated that curative effects of ultraviolet light resulted from the formation of vitamin D by such irradiation. Pure vitamin D2 was first isolated in 1930–31 in England and in Germany.Two rare, closely related diseases, familial hypophosphatemia and osteomalacia (adult rickets), arise from the abnormal metabolism of phosphorus and calcium and result in the abnormal mineralization of bone and rickets-type deformities. Familial hypophosphatemia, also called vitamin D resistant rickets, is an uncommon disorder apparently caused by an increased rate of phosphate clearance from the body by the renal tubules of the kidneys, resulting in loss of bone mineral and, in severe cases, in rickets-type deformities and dwarfism. The disease, which is heritable (usually sex-linked dominant), tends to start slightly later in life than vitamin D deficiency rickets and is treated with massive doses of vitamin D and supplementary phosphate and calcium. A number of similar but little-understood syndromes exist, grouped under the name de Toni-Fanconi syndrome (de Toni–Fanconi syndrome) and characterized by rickets deformities and renal tubule defects.
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См. также в других словарях:
rickets — disease caused by vitamin D deficiency, 1630s, of uncertain origin. Originally a local name for the disease in Dorset and Somerset, England. Some derive it from a Dorset word, rucket to breathe with difficulty, but the sense connection is… … Etymology dictionary
rickets — ► NOUN (treated as sing. or pl. ) ▪ a disease of children caused by vitamin D deficiency, characterized by softening and distortion of the bones. ORIGIN perhaps an alteration of Greek rhakhitis rickets … English terms dictionary
Rickets — Rick ets, n. pl. [Of uncertain origin; but cf. AS. wrigian to bend, D. wrikken to shake, E. wriggle.] (Med.) A disease which affects children, and which is characterized by a bulky head, crooked spine and limbs, depressed ribs, enlarged and… … The Collaborative International Dictionary of English
rickets — rickets. См. гиповитаминоз D. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) … Молекулярная биология и генетика. Толковый словарь.
rickets — [rik′its] n. [altered < ? Gr rhachitis,RACHITIS] a disease of the skeletal system, chiefly of children, resulting from absence of the normal effect of vitamin D in depositing calcium salts in the bone, and characterized by a softening and,… … English World dictionary
Rickets — Infobox Disease Name = Rickets ICD10 = ICD10|E|55| |e|50 ICD9 = ICD9|268 Caption = A family with rickets. Paris, 1900. DiseasesDB = 9351 eMedicineSubj = ped eMedicineTopic = 2014 MedlinePlus = 000344 MeshName = Rickets MeshNumber = D012279Rickets … Wikipedia
Rickets — A disease of infants and children that disturbs normal bone formation (ossification). Rickets is a failure to mineralize bone. This softens bone (producing osteomalacia) and permits marked bending and distortion of bones. Up through the first… … Medical dictionary
rickets — n. a disease of childhood in which the bones do not harden due to a deficiency of vitamin D. Without vitamin D, not enough calcium salts are deposited in the bones to make them rigid: consequently they become soft and malformed. This is… … The new mediacal dictionary
rickets — [[t]rɪ̱kɪts[/t]] N UNCOUNT Rickets is a disease that children can get when their food does not contain enough Vitamin D. It makes their bones soft and causes their liver and spleen to become too large … English dictionary
rickets — noun plural but singular in construction Etymology: origin unknown Date: 1634 a deficiency disease that affects the young during the period of skeletal growth, is characterized especially by soft and deformed bones, and is caused by failure to… … New Collegiate Dictionary