Chap 42: Bone Mineral Homeostasis

Introduction
- Ca + PO4 - 2 most important minerals for cell function
- Bone is major storage

• 98% of total 1-2kg of Ca
• 85% of 1kg of PO4

- 2 hormones important - PTH and Vit D
-
Non hormonal agents affecting bone mineral homeostasis
Bisphosphonates
- analog of pyrophosphate
- inhibit formation and dissolution of hydroxyapatite crystals in/out skeletal system
- predilection for bone - effects come from osteoclasts
- <10%> take with empty stomach --> 50% accumulates in bone, 50% renally excreted unchanged
- SE:

• gastric irritation/esophageal irritation --> glass of H2O, sitting upright 30 mins
• osteonecrosis of the jaw
• renal damage

- clinical uses

• alendronate - seemed to increases bone mineral density over 2 yrs hence used in osteoporosis/# NOF
• zolendronate - hyperCa 2ary to malignancy
• pamidronate - same as above but cheaper, less potent

d