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Titolo:
Vitamin D therapy of osteoporosis: Plain vitamin D therapy versus active vitamin D analog (D-hormone) therapy
Autore:
Lau, KHW; Baylink, DJ;
Indirizzi:
Loma Linda Univ, Dept Med, Loma Linda, CA 92357 USA Loma Linda Univ Loma Linda CA USA 92357 ept Med, Loma Linda, CA 92357 USA Jerry L Pettis Mem Vet Adm Med Ctr, Musculoskeletal Dis Ctr 151, Loma Linda, CA 92357 USA Jerry L Pettis Mem Vet Adm Med Ctr Loma Linda CA USA 92357, CA 92357 USA
Titolo Testata:
CALCIFIED TISSUE INTERNATIONAL
fascicolo: 4, volume: 65, anno: 1999,
pagine: 295 - 306
SICI:
0171-967X(199910)65:4<295:VDTOOP>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
BONE-MINERAL DENSITY; GROWTH-FACTOR-BETA; CALCIUM-ABSORPTION; D SUPPLEMENTATION; POSTMENOPAUSAL OSTEOPOROSIS; ELDERLY WOMEN; SENILE OSTEOPOROSIS; PARATHYROID-HORMONE; SERUM 1,25-DIHYDROXYVITAMIN-D; D METABOLITES;
Keywords:
osteoporosis; vitamin D therapy; calcitriol therapy; alfacalcidol therapy (human);
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
94
Recensione:
Indirizzi per estratti:
Indirizzo: Lau, KHW Loma Linda Univ, Dept Med, 11201 Benton St, Loma Linda, CA 92357 USA Loma Linda Univ 11201 Benton St Loma Linda CA USA 92357 92357 USA
Citazione:
K.H.W. Lau e D.J. Baylink, "Vitamin D therapy of osteoporosis: Plain vitamin D therapy versus active vitamin D analog (D-hormone) therapy", CALCIF TIS, 65(4), 1999, pp. 295-306

Abstract

Normal intestinal calcium (Ca) absorption is an essential feature of bone homeostasis. As with many other organ systems, intestinal Ca absorption declines with aging, and this is one pathological factor that has been identified as a cause of senile osteoporosis in the elderly. This abnormality leads to secondary hyperparathyroidism, which is characterized by high serum parathyroid hormone (PTH) and an increase in bone resorption. Secondary hyperparathyroidism due to poor intestinal Ca absorption has been implicated notonly in senile osteoporosis but also in age-related bone loss. Accordingly, in population-based studies, there is a gradual increase in serum PTH from about 20 years of age onward, which constitutes a maximum increase at 80 years of age of 50% of the basal value seen at 30 years of age. The cause of the increase in PTH is thought to be partly due to impaired intestinal Caabsorption that is associated with aging, a cause that is not entirely clear but at least in some instances is related to some form of vitamin D deficiency. There are three types of vitamin D deficiency: (1) primary vitamin D deficiency, which is due to a deficiency of vitamin D, the parent compound; (2) a deficiency of 1,25(OH)(2)D-3 resulting from decreased renal production of 1,25(OH)(2)D-3; and (3) resistance to 1,25(OH)(2)D-3 action owing to decreased responsiveness to 1,25(OH)(2)D-3 of target tissues. The cause for the resistance to 1,25(OH)(2)D-3 could be related to the finding that the vitamin D receptor level in the intestine tends to decrease with age. Allthree types of deficiencies can occur with aging, and each has been implicated as a potential cause of intestinal Ca malabsorption, secondary hyperparathyroidism, and senile osteoporosis. There are two forms of vitamin D replacement therapies: plain vitamin D therapy and active vitamin D analog (orD-hormone) therapy. Primary vitamin D deficiency can be corrected by vitamin supplements of 1000 U a day of plain vitamin D whereas 1,25(OH)(2)D-3 deficiency/resistance requires active vitamin D analog therapy [1,25(OH)(2)D-3 or 1 alpha(OH)D-3] to correct the high serum PTH and the Ca malabsorption. In addition, in the elderly, there are patients with decreased intestinalCa absorption but with apparently normal vitamin D metabolism. Although the cause of poor intestinal Ca absorption in these patients is unclear, these patients, as well as all other patients with secondary hyperparathyroidism (not due to decreased renal function), show a decrease in serum PTH and an increase in Ca absorption in response to therapy with 1,25(OH)(2)D-3 or 1alpha(OH)D-3. In short, it is clear that some form of vitamin D therapy, either plain vitamin D or 1,25(OH)(2)D-3 or 1 alpha(OH)D-3, can be used to correct all types of age-dependent impairments in intestinal Ca absorption and secondary hyperparathyroidism during aging. However, from a clinical standpoint, it is important to recognize the type of vitamin D deficiency in patients with senile osteoporosis so that primary vitamin D deficiency can be appropriately treated with plain vitamin D therapy, whereas 1,25(OH)(2)D-3 deficiency/resistance will be properly treated with 1,25(OH)(2)D-3 or 1 alpha(OH)D-3 therapy. With respect to postmenopausal osteoporosis, there is strong evidence that active vitamin D analogs (but not plain vitamin D) mayhave bone-sparing actions. However, these effects appear to be results of their pharmacologic actionson bone formation and resorption rather than through replenishing a deficiency.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 18/09/20 alle ore 11:13:50