¼±Åà - È­»ìǥŰ/¿£ÅÍŰ ´Ý±â - ESC

 

Bone & mineral metabolism

1. Bone structure & metabolism

i) organic matrix : type I collagen(90-95%)

noncollagenous portion of the organic matrix

: albumin & ¥á2-HS glycoproteins ±â¿ø protein

¥á-carboxyglutamic acid(GLA)[bone GLA protein=BGP, osteocalcin

& matrix GLA protein], glycoprotein osteonectin,

phosphoprotein osteopontin, sialoproteins, thrombospondinµîÀÇ ´Ü¹é

ii) mineral phase : Ca, P, crystalline hydroxyapatite

* osteoblast: TGF-¥â type I, II, acidic fibroblast growth factor(aFGF)

basic fibroblast GF(bFGF), PDGF, IGF-I, II¿Í °°Àº growth factor°¡ stimulation

* osteoclast

2. Calcium metabolism 1-2 kg >98% skeleton

normal: 8.8 - 10.4 mg/dL

* 3 forms i) free ions

ii) plasma protein°ú °áÇÕ

iii) diffusible complex

protein-bound Ca = 0.8¡¿Alb + 0.2¡¿globulin + 3

* corrected Alb°è»ê¹ý

s-Alb level < 4.0 g/dL¿¡¼­ Alb 1g/dL´ç s-Ca 1mg/dL¾¿ º¯È­

¿¹> s-Ca = 7.8, s-Alb =3.0À̶ó¸é

corrected Ca = 8.8 mg/dL

* Ca source

intestinal tractÀ¸·ÎºÎÅÍ Èí¼ö(¡­100-200 mg/d)

bone mineral·Î ºÎÅÍÀÇ ÀçÈí¼ö(¡­100 mg/d)¿¡ ÀÇÇØ plasma·Î À¯ÀԵȴÙ.

urinary excretion: ¡­50-300 mg/d

Á¤»ó ¹Ì±¹¼ºÀÎÀÇ ÇÏ·ç Ca¼·Ãë·®Àº 600-800 mgÀε¥ ÀÌÁß ¹ÝÀÌ Èí¼öµÇ¸ç

osteoporosis¸¦ ¿¹¹æÇϱâ À§ÇÑ ÇÏ·ç Çʿ䷮Àº 800-1500 mgÀÌ´Ù.

Fig 340-3 calcium homeostasis

Intestine ¢¢ ECF ¢¢ Bone

(500-1500) ¡¡ (900-1400)

kidney

(150-300)

4. Vitamin D

7-dehydrocholesterol --> previtamin D3 --> vit D3 --> 25(OH)vit D3 --> 1,25(OH)2D3

(UVB) (liver) (kidney)

* ÀÛ¿ë

intestine¿¡¼­ Ca, P Èí¼ö Áõ°¡

bone¿¡¼­ Ca Èí¼ö Áõ°¡(resorption¡è) <- osteoclast¼ö¸¦ Áõ°¡½ÃÅ´À¸·Î½á

Parathyroid¿¡¼­ PTH ¾ïÁ¦

ÃÖÁ¾ÀûÀ¸·Î Ç÷Áß Ca, P ³óµµ¸¦ Áõ°¡½ÃÅ´