title: [Vitamin D deficiency in adults: to better understand a new presentation of an old disease].
abstract: Vitamin D is synthesized in skin through a reaction mediated by sunlight, and it is metabolized to 25-hydroxyvitamin D, in liver, and in 1,25-dihydroxyvitamin D, in kidney. This last reaction has a tight feedback mechanism. 1,25-dihydroxyvitamin D is the active hormone, and its actions are mediated mainly by nuclear receptors. Its major functions are in calcium metabolism and bone mass maintenance. Hypovitaminosis D, as a disease in adult people, manifests itself with hypocalcemia and secondary hyperparathyroidism with subsequent loss of trabecular bone, thinning of cortical bone, and, eventually, a higher risk of fractures. Hypovitaminosis D is a very common condition in Europe, Africa, North America and some South American countries, such as Chile and Argentina. Measurement of serum total 25-hydroxyvitamin D concentration is the gold standard to diagnose vitamin D deficiency. Serum concentrations below 50 nmol/L are associated with an increase in parathyroid hormone concentration, and bone loss. Risk factors for vitamin D deficiency, like poor sunlight exposition, aging skin and factors that interfere with normal vitamin D metabolism, are well established. Oral vitamin D supplementation, an easy and inexpensive treatment, is needed to treat this illness.
authors.affiliation: Departamento de Medicina Interna, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS.
authors.forename: Melissa Orlandin
authors.initials: MO
authors.lastname: Premaor
authors.forename: Tania Weber
authors.initials: TW
authors.lastname: Furlanetto
mesh_terms: D000328:Adult; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000209:etiology; D006996:Hypocalcemia / Q000209:etiology; D010024:Osteoporosis / Q000209:etiology; D012307:Risk Factors; D012720:Severity of Illness Index; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000097:blood / Q000502:physiology*; D014808:Vitamin D Deficiency / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology; D014815:Vitamins / Q000008:administration & dosage
chemical_list: D014815:Vitamins; D014807:Vitamin D; C104450:25-hydroxyvitamin D