Week 4 - Osteoporosis Flashcards
What is osteoporosis?
A systemic skeletal disease with low bone mass & architectural deterioration of bone tissue WITH a consequent increase in bone fragility and susceptibility to fracture.
What are the main constituents of bone?
- Matrix (90%collagen; 10%proteins)
- Mineral (hydroxyapatite)
- Cells (osteo-blasts, -cytes, & -clasts)
What are the functions of cortical bone?
- protection from trauma
- attachment of tendons & ligaments
- provides biomechanical strength
What are the functions of trabecular bone?
- mineral metabolism
- strength & elasticity
Which part of bone is most rapidly mobilized when body needs Calcium/phosphate?
Trabecular bone
Where does PTH act & what does it do?
Bone - Ca & PO4 resorption
Kidney - Ca resorption; PO4 secretion
- also increases Calcitriol which acts on the intestine
Where does Calcitriol act & what does it do?
Bone - Ca & PO4 resorption
Kidney - Ca & PO4 reabsorption
Intestines - Ca & PO4 absorption
What are the determinants of healthy bone?
Structure/Mechanical - (fracture, BMD, architecture, biopsy)
Cell Function - (bone turnover)
Clinical risk factors/bone quality - (FRAX, CAROC, previous fall)
What contributes to low bone mass?
- Low PBM (peak bone mass)
- Age-related bone loss
- Post-menopausal bone loss
What are some risks for getting fractures?
- Low bone mass
- Clinical risk factors for falling
- Poor bone quality/architecture
- high BMI
- parental hx of fractures
- smoker
- any long-term use of glucocorticoids
- RA
- alcohol (3+ drinks/day)
Briefly explain fracture epidemiology.
Peak in adolescence: males»females (usually trauma)
Rise with older age: females»males (rises after female age 40; male age 70)
What are some types of vertebral fractures?
- wedge
- crush
- endplate
How is bone mass/density assessed?
Plain films, DXA, CT, US
What is the numerical cut point for a WHO dx of osteoporisis?
T score <= -2.5
What is osteopenia?
Loss of bone mass with T-score between -1 and -2.5
What is severe osteoporosis?
Osteoporosis (T<= -2.5) with fracture
What is the difference between a T-score and a Z-score for fracture risk?
T-score is related to peak bone mass;
Z-score is an age-matched score for declining normal bone mass or developing bone
What is the mechanism of Teriparatide?
- recombinant form of PTH
- anabolic agent (builds bone)
- INTERMITTENT USE stimulates more than osteoclasts
What tool has the WHO made for assessing fracture risk?
FRAX
Who is teriparatide given to?
Post-menopausal women with high risk of fracture.
Men or women who failed to respond to previous osteoporosis therapy.
What is the function of giving PTH as one dose/day?
Increases bone-forming potential
What is the classification criteria for severe osteoporosis?
T-score < -2.5 & previous fracture
What accounts for the larger peak bone mass in males compared to women?
Androgens
Compare incidence and mortality for fractures in men and women.
Men have lower incidence of fractures but higher mortality. Because fractures in women are more often due to osteoporosis but fractures in males usually happen if they are very sick already.
