Metabolic Bone Diseases
Terms
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- Osteoporosis
- Parallel loss of both mineral + matrix; mineralized bone no longer adequate to withstand minor trauma without fracture.
- Osteomalacia
- Pathologic loss of mineralized bone due to ↓ in Ca2+ or phosphorus levels below that required for normal mineralization of bone (mineral loss > matrix loss).
- Estrogen
- Which agent is especially effective in osteoporosis patients with premature menopause (<45 y/o)?
- Cyclic form (25 days out of 30)
- What type of dosing is used for estrogen therapy?
- Cyclic administration w/progesterone
- Administration of estrogen poses an increased risk of malignancy. How can this increased risk be avoided?
- Breast cancer; stroke; venous thromboembolism; CAD
- What does estrogen treatment increase the risk for?
- Colon cancer
- What does estrogen treatment decrease the risk for?
- 6
- Estrogen therapy gives 50% ↓ of fractures if it is administered for at least how many years?
- 75
- At what age will estrogen therapy no longer provide continued protection?
- Selective estrogen receptor modulators (SERMs)
- Produces estrogen-like effects in some tissues & estrogen-blocking effects in others.
- Bisphosphonates
- Alendronate, risedronate, & zoledronate.
- Bisphosphonates
- Agents that ↑ bone density & ↓ vertebral/hip fractures.
- Take it in the morning w/water, then remain upright for 45 minutes w/out eating or lying down
- Because bisphosphonates are poorly absorbed by the oral route, what must be done in order to administer it orally?
- Nasal spray
- How is calcitonin typically administered?
- Weaker
- How does calcitonin compare with bisphosphonates & PTH in regards to its effect on bone mineral density & anti-fracture efficacy?
- When other therapies are not tolerated
- When is calcitonin indicated for osteoporosis treatment?
- Bone fractures; loss of height; ↑ dorsal kyphosis; bony pain; muscle stiffness/weakness
- What are the S/S of osteoporosis/osteopenia?
- General aching and fatigability; proximal myopathy; periarticular tenderness; sensory polyneuropathy
- What are the S/S of osteomalacia?
- ↑ risk of fracture
- How are glucocorticoids associated with osteopenia?
- Trabecular
- Does glucocorticoid induced osteopenia demonstrate a greater loss in trabecular bone or compact cortical bone?
- Resorption > formation because they induce a negative overall Ca2+ balance
- Though the cause is unknown, what is the net result of glucocorticoids on bone remodeling and why is this the case?
- ↓ intestinal Ca2+ absorption & ↑ UCa2+ excretion; ↓ conversion of precursor cells to osteoblasts, ↓ synthesis of osteoid by osteoblasts, stimulation of PTH leading to activation of osteoclasts
- What are the possible mechanisms by which glucocorticoids induce osteopenia?
- Complete withdrawal of glucocorticoids (if possible) + Ca2+/Vit D supplements + bisphosphonate
- What is the treatment plan for glucocorticoid induced osteopenia?