ⅵ itamin d deficiency 科医院徐秀
儿 科 医 院 徐 秀 Vitamin D deficiency
skin 7-dehydrocholesterol Ultraviolet light Provitamin d Vitamin D (an inactive form) In the Li Hydroxylation 25-hydroxy vitamin D3 In the kidneys: Hydroxylation 1, 25-hydroxy vitamin D3 active form) Vitamin D Synthesis and Activation
Provitamin D3 Ultraviolet light In the skin: 7-dehydrocholesterol Vitamin D3 (an inactive form) 25-hydroxy vitamin D3 Hydroxylation In the Liver: foods 1, 25-hydroxy vitamin D3 (active form) Hydroxylation In the kidneys: Vitamin D Synthesis and Activation
Vitamin d roles Facilitate intestinal absorption of calcium and phosphorus Promote renal reabsorption of phosphorus Direct effect on bone deposition and reabsorption of calcium and phosphorus Maintain calcium and phosphorus homeostasis
Vitamin D roles ➢ Facilitate intestinal absorption of calcium and phosphorus ➢ Promote renal reabsorption of phosphorus ➢ Direct effect on bone deposition and reabsorption of calcium and phosphorus ➢ Maintain calcium and phosphorus homeostasis
Kidneys 1,25(OH)2D +1,25(OH)2D +PTH -PTH CT Bone -CT Ca P Homeostasis Parathormone +1,25(OH)2D (PTH) 1,25(OH)2D Calcitonin (CT) Intestine Ca P Homeostasis
Ca, P Homeostasis +1,25(OH)2D +PTH -CT +1,25(OH)2D -PTH -CT +1,25(OH)2D Bone Intestine Kidneys Parathormone (PTH) Calcitonin (CT) 1,25(OH)2D Ca, P Homeostasis
Causes of Vitamin D deficiency Inadequate direct exposure to sunlight > Inadequate vitamin d intake Higher requirement Some diseases. which interfere with vitamin D absorption or meta bolic and activation
Causes of Vitamin D deficiency ➢ Inadequate direct exposure to sunlight ➢ Inadequate vitamin D intake ➢ Higher requirement ➢ Some diseases, which interfere with vitamin D absorption or metabolic and activation