Vitamin d deficiency 科医院徐秀
儿 科 医 院 徐 秀 Vitamin D deficiency
skin 7-dehydrocholesterol Ultraviolet light Provitamin D3 food Vitamin d (an inactive form) In the Liver Hydroxylation In the 25-hydroxy vitamin D3 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 CT Bone -CT Ca P Homeostasis Parathormone +1,25(OH)2D (PTH) Calcitonin 1,25(OH)2D (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 metabolic 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
Vitamin d-Deficient rickets Epidemiology: rare in industrialized countries Common in China 20% in the South of china 30-40% in the north of china
Vitamin D-Deficient Rickets Epidemiology: ➢ rare in industrialized countries ➢ Common in China 20% in the South of China 30-40% in the North of China
Vitamin D deficiency Osteoid tissue Less ca absorbed from the intestin failure to mineralize Serum ca concentration decrease Osteoid tissue Parathormone accumulation secreted Urine phosphorus Low Mobilized increased serum bone ca p phosphor Normal o! Slight decrease in serum calcium concentration Serum AKP Vitamin D-deficient increased Rickets Pathophysiology of Vitamin D-deficient Rickets
Vitamin D deficiency Osteoid tissue failure to mineralize Osteoid tissue accumulation Less Ca absorbed from the intestine Urine phosphorus increased Parathormone secreted Serum AKP increased Mobilized bone Ca,P Vitamin D-deficient Rickets Serum Ca concentration decrease Low serum phosphor us Pathophysiology of Vitamin D-deficient Rickets Normal or slight decrease in serum calcium concentration
Cliniacl manifestations General manifestations: irritability, temporary teeth eruption delayed, anterior fontanel closure delayed Muscles lack of tone Head: craniotabes, Ping-Pong ball, caput quadratum Chest: beading of the ribs pigeon breast deformity, Harrison groove Limb: Thickening of the wrists and ankles Bow-legs, knock-knees
➢ General manifestations: irritability, temporary teeth eruption delayed，anterior fontanel closure delayed ➢ Muscles lack of tone ➢ Head: craniotabes, Ping-Pong ball,caput quadratum ➢ Chest: beading of the ribs, pigeon breast deformity, Harrison groove ➢ Limb: Thickening of the wrists and ankles Bow-legs, knock-knees Cliniacl manifestations
Caput quadratum
Caput quadratum
Pigeon breast deformity
Pigeon breast deformity