Ch.41 Osteoporosis Flashcards
What is the osteoporosis according to WHO?
BMD of 2.5 standard deviations below peak bone mass of young healthy adults
What is a T score?
Amount of bone density compared to a 35 yo adult of same gender with peak bone mass
What is a Z score?
Comparison of bone mass made with same age, sex, race, height and wt
What is a normal BMD T score?
T score of -1 or >
What is an osteopenic T score?
T score b/w -1 to -2.5
What is an osteoporotic T score?
T score of
What is severe osteoporosis?
T score of
How much bone is replaced annually?
20%
What are osteoclasts?
Bone cells that resorb calcified matrix
What are osteoblasts?
Bone cells that synthesize new bone matrix
Describe the activation phase of bone remodeling
Osteoclastic activity recruited
Describe the resorption phase of bone remodeling
Osteoclasts erode bone and form a cavity
Describe the Reversal phase of bone remodeling
Osteoblasts are recruited
Describe the formation phase of bone remodeling
Osteoblasts replace cavity with new bone
Describe the quiescence phase of bone remodeling
Bone tissue remains dormant until the next cycle starts
What endocrine disorders can increase rate of bone remodeling?
Thyrotoxicosis
Hyperparathyroidism
What is primary osteoporosis?
Rare idopathic juvenile d/o b/w 8-14 yo w/ inc osteoclastic activity for 2-4 years
Which hormones inc bone remodeling?
PTH
Thyroxine
GH
Vitamin D
Which hormones dec bone remodeling?
Calcitonin
Estrogen
Glucocorticoids
What does PTH do in the presence of Vit D?
Stim bone resporption and release of Ca and P
What does Calcitrol do?
Produced by kidneys and inc intestinal absorption of Ca and P
What does Calcitonin do?
Prohibits Ca and P resorption by inhibiting osteoclastic activity
What does active Vit D do?
Inc intestinal absorption of Ca and P
How is Vit D synthesized?
Sun exposure and conversion in the liver
How does age affect bone remodeling?
Osteoblast activity dec
Active form of Vit D-1,25(OH)2 dec ~50%
GH dec which stim renal prod of vit D
What are the MC locations for osteoporotic fx?
Midthoracic and upper-lumbar spine
Proximal femur
Distal forearm (Colles fx)
What is the risk of death with osteoporotic hip fx?
15% to 20%
How does the risk of osteoporotic fx change with every SD of dec in BMD?
- 5-2.0 fold inc in spine fx
2. 6 fold inc in hip fx
How is a typical limb with hip fx positioned?
Externally rotated and shortened
Who is at inc risk of osteoporosis?
Estrogen def women Women >65 yo Type I DM Liver dz Kidney dz Thyroid dz FHx of osteoporosis Early menopause Cigarette smokers Alcohol abuse
What can use of the spinal proprioceptive extension exercise dynamic (SPEED) program do?
Dec fall risk and falls at obstacles Dec step width Improve gait steadiness Inc velocity Inc Cadence Inc Stride length
What is the recommendation for walking to dec osteoporosis risk?
45 min 3x/wk or 30 min daily
What exercises should be avoided in osteoporosis?
Spinal flexion
What are anti-resoprtive agents?
Estrogens
Androgens
Calcitonin
Bisphosphonates
What are osteoblast stimulator agents?
Fluoride (not approved in US d/t risk of appendicular fx)
PTH
What is a contraindication of PTH therapy?
Hx of cancer
What are the SE of PTH therapy?
Nausea Dizziness Leg cramps HA Hypercalcemia
What is a SE of bisphosphonates?
Osteonecrosis of the jaw
What are contraindications of estrogen therapy?
Hx of thromboembolism or thrombophlebitis
Suspected breast or endometrial CA
Liver or gallbladder dz
CV dz
What does use of progesterone with estrogen dec risk of?
Endometrial hpyerplasia and CA
How should Alendronate be taken?
10 mg/day or 70 mg/wk
W/ full glass of water on awakening
No eating or reclining for 30-45 min after dose d/t esophageal irritation
How should Risedronate be taken?
5 mg/day or 35 mg/wk
What doe thiazide diuretics do?
Inhibit urinary excretion of Ca and slow bone loss dec rate of fx
