Vad gör kalcitriol

d-vitamin brist symtom

Calcitriol is a hormone and the active form of vitamin D , normally made in the kidney. It binds to and activates the vitamin D receptor in the nucleus of the cell, which then increases the expression of many genes. It can be given as a medication for the treatment of low blood calcium and hyperparathyroidism due to kidney disease , low blood calcium due to hypoparathyroidism , osteoporosis , osteomalacia , and familial hypophosphatemia , [ 7 ] [ 12 ] and can be taken by mouth or by injection into a vein.

Calcitriol was identified as the active form of vitamin D in and the drug was approved for medical use in the United States in Calcitriol is prescribed for: [ 16 ]. Calcitriol has been used in an ointment for the treatment of psoriasis , [ 17 ] although the vitamin D analogue calcipotriol calcipotriene is more commonly used. Compared to other vitamin D compounds in clinical use cholecalciferol , ergocalciferol , calcitriol has a higher risk of inducing hypercalcemia.

However, such episodes may be shorter and easier to treat due to its relatively short half-life. High calcitriol levels may also be seen in human disease states in patients not on supplementation. In someone with hypercalcaemia and high calcitriol levels, low intact parathyroid hormone levels are usually present.

The major conditions with hypercalcaemia due to elevated calcitriol levels are lymphoma , tuberculosis and sarcoidosis where excess production occurs due to ectopic 25 OH Dhydroxylase CYP27B1 expressed in macrophages. Some plants contain glycosides of 1,dihydroxycholecalciferol. Consumption of these glycosides by grazing animals leads to vitamin D toxicity, resulting in calcinosis , the deposition of excessive calcium in soft tissues.

Three rangeland plants, Cestrum diurnum , Solanum malacoxylon , and Trisetum flavescens , are known to contain these glycosides. Of these, only C. Calcitriol acts in concert with parathyroid hormone PTH in all three of these roles. For instance, PTH also indirectly stimulates osteoclasts. The resulting decrease in serum phosphate causes hydroxyapatite Ca 5 PO 4 3 OH to dissolve out of bone, thus increasing serum calcium.

PTH also stimulates the production of calcitriol see below. Many of the effects of calcitriol are mediated by its interaction with the calcitriol receptor , also called the vitamin D receptor or VDR. When calcitriol binds to the receptor, the ligand -receptor complex translocates to the cell nucleus , where it acts as a transcription factor promoting the expression of a gene encoding a calcium binding protein.

Thus calcitriol also stimulates the intestinal absorption of phosphate. The observation that calcitriol stimulates the release of calcium from bone seems contradictory, given that sufficient levels of serum calcitriol generally prevent overall loss of calcium from bone. It is believed that the increased levels of serum calcium resulting from calcitriol-stimulated intestinal uptake causes bone to take up more calcium than it loses by hormonal stimulation of osteoclasts.

Calcitriol also inhibits the release of calcitonin , [ 28 ] a hormone which reduces blood calcium primarily by inhibiting calcium release from bone. Calcitriol is produced in the cells of the proximal tubule of the nephron in the kidneys by the action of hydroxyvitamin D 3 1-alpha-hydroxylase , a mitochondrial oxygenase and an enzyme which catalyzes the hydroxylation of hydroxycholecalciferol calcifediol in the 1-alpha position.

The activity of this enzyme is stimulated by PTH. Calcitriol is also produced outside the kidney in small amounts by many other tissues including placenta and activated macrophages. When the drug alfacalcidol is used, hydroxylation in the liver produces calcitriol as the active metabolite. This will produce greater effects than other vitamin D precursors in patients with kidney disease who have loss of the renal 1-alpha-hydroxylase.

Click on genes, proteins and metabolites below to link to respective articles. The halflife of calcitriol in the body is measured in hours, unlike its precursor calcifediol, whose halflife is measured in weeks. This occurs through the action of the CYP24A1 hydroxylase. It was first identified in by Michael F. Holick working in the laboratory of Hector DeLuca , [ 35 ] [ 36 ] and also by Tony Norman and colleagues.

It was approved for medical use in the United States in Calcitriol refers specifically to 1,dihydroxycholecalciferol. Because cholecalciferol already has one hydroxyl group, only two 1,25 are further specified in this nomenclature, but in fact there are three 1,3,triol , as indicated by the name calcitriol. The 1-hydroxy group is in the alpha position, and this may be specified in the name, for instance in the abbreviation 1α, OH 2 D 3.

Calcitriol is, strictly, the 1-hydroxylation product of calcifediol OH vitamin D 3 , derived from cholecalciferol vitamin D 3 , rather than the product of hydroxylations of ergocalciferol vitamin D 2.

d-vitamin referensvärde

Indeed, both bind to the vitamin D receptor and produce biological effects. Contents move to sidebar hide. Article Talk. Read Edit View history. Tools Tools. Download as PDF Printable version. In other projects. Wikidata item. Active form of vitamin D. US DailyMed : Calcitriol. AU : B3. IUPAC name. DB Y. Interactive image. Medical use [ edit ]. Adverse effects [ edit ]. Mechanism of action [ edit ].

Biosynthesis and its regulation [ edit ]. Interactive pathway map [ edit ]. Metabolism [ edit ]. History [ edit ].

d-vitaminbrist symptom vuxna

Names [ edit ]. References [ edit ]. Recommendations ". European Journal of Biochemistry. May PMID American Society of Health-System Pharmacists. Retrieved 9 April Nature Reviews. Drug Discovery. S2CID Academic Press. ISBN Retrieved 31 October The American Journal of Clinical Nutrition. Pharmaceutical Press. Archived from the original on 15 January Retrieved 14 January The selection and use of essential medicines web annex A: World Health Organization model list of essential medicines: 23rd list Geneva: World Health Organization.

Rossi S ed. Australian Medicines Handbook. Journal of Drugs in Dermatology. Expert Review of Clinical Pharmacology. Oral or topical use of 1,dihydroxyvitamin D3 can be a safe and effective therapy for psoriasis". Journal of the American Academy of Dermatology. Arthritis and Rheumatism. Endocrine Reviews. PMC Plants Poisonous to Livestock. Cornell Department of Animal Science.

Retrieved 16 June Harrison's Principles of Internal Medicine 17th ed. Physiological Reviews. Molecular Endocrinology. Archives of Biochemistry and Biophysics. Current Vascular Pharmacology. Clinical Cases in Mineral and Bone Metabolism.