Osteoporosis Flashcards
What is the characteristic defect in osteoporosis?
diminished organic BONE MATRIX rather than poor bone calcification (decreased osteoid deposition)
What does bone look like in osteoporosis?
thinning cortex
emptying trabeculae
What is bone mineral density (BMD) reported as? what is the value for:
- osteoporosis?
- osteopenia?
T score
- T >2.5 Stan. dev. below avg
- 2.5 > T > 1 stan. dev. below avg
What is the usual cause of rickets?
chronic vit D deficiency
Whats the diff between osteoporosis and rickets
osteoporosis: diminished organic bone matrix
rickets: deficient bone MINERALIZATION, bone PAIN!!
What are Sx of rickets?
changes at the growth plate caused by deficient mineraliztion - occurs before the closure of the growth plates
- pain in spine, pelvis, legs, muscle weakness
- Softened growth plates
- Seizures
- Dental defects
What is the Tx of Rickets?
adequate Ca and Phosphate in diet
large amnts of Vit D
What is Osteomalacia and how is it caused?
“Adult Rickets”
can be caused by Steatorrhea (cant absorb fat)
Vit D not absorbed
Calcium not absorbed
Who is mortality a/w factures higher in?
Men
Where is the most common site of fractures in osteoporosis?
Spine
prox femur = 14%, 3/4 cost
What are 3 factors that account for 60-80% of variability in skeletal development?
- Heritable Factors
- Gender
- Ethnicity
What are 2 factors in development of osteoporosis?
- Magnitude of bone acquisition during adolescence and young adulthood
- Rate of bone loss later
What is the age of peak bone mass for:
- prox femur
- spine
- 18-20
2. 25-30
How does menopause cause natural bone loss?
Decline in estrogen = decline in OPG
RANKL causes osteoclast maturation
OPG binds up RANKL
decreased OPG = increase RANKL activity = bone loss
What are natural bone loss factors in men?
- reduced aromatase activity in fat tissue = reduced estrogen = bone loss
- Decline in circulating IGF-1
What are some cellular signalling factors associated with aging bone loss?
Increased PPARG-gamma
-commits stem cells toward adipocyte and away from osteoblast differentiation (increase in bone marrow adiposity)
What are secondary factors in osteoporosis (identified in 1/4 of osteoporosis pts)
- parental history of fx
- Endocrine disorders
- GLUCOCORTICOIDS (#1 secondary cause)
- Anorexia Nervosia
- Alcohol - suppresses osteobasts
What is the definition of a Fragility Fracture?
fx from falling from standing height
What are the 4 major osteoporotic fracture sites?
- Spine
- Prox femur
- Distal forearm
- Proximal humerus
What is the screening for osteoporosis?
DXA
What are Bone Tumor Markers (and examples)
elevated BTMS = a/w increase risk of fx Osteocalcin Alkaline phosphatase urinary hydroxyproline urinary C-telopeptide
Who should you screen for Bone Mineral Density (BMD)
women: 65 or older
Men: only if signs of low bone mass
What are the best locations to test BMD by DXA?
hip and spine (National osteoporosis foundation)
-forearm and heel if hip and spine not available
What are
- T scores
- Z scores
- BMD compared w a young adult
2. BMD compared to peers
