Osteoperosis Flashcards
What is osteoporosis?
Low bone mineral density that increases risk of fractures. Asymptomatic till fractures. (T score
Primary causes
Combination of oestrogen deficiency and ageing
Secondary causes
Potentially reversable cause
Should be considered in non ‘at-risk’ groups
What do osteoblast respond to?
Parathyroid hormones secreted by the parathyroid glands. These bind to the receptors on osteoblasts.
What does the binding of parathyroid hormones to osteoblasts do?
Causes osteoblasts to express RANKL which binds on to the RANK on pre mature osteoclasts.
What does the activation of premature osteoclasts via RANKL do?
Releases enzymes and acids to breakdown bone.
Osteoprotegerin (OPG) function
Prevents RANKL dining to RANK, so prevents the activation of osteoclasts.
What are Bisphosphonates
Anti-resorptive agents
When are bisphosphonates used?
First-line treatment in:
- post-menopausal women
- men >50
- Gluccorticoid induced
How do bisphosphonates work? (4)
- Binds to hydroxyapatite sites on bone tissue surface
- Bisphosphonates are taken up by osteoclasts in bone resorption.
- Osteoclasts apoptosis
- Reduced bone resorption
Side effect of bisphosphonates
- Osteonecrosis of jaw
- Atypical femoral fractures (Long term)
- Hypocalcemia
- Hypophosphatemia
- Renal impairment
- Musculoskeletal pain
- GI disturbance
When to take bisphosphonates?
Morning and evening 30 mins before meals to avoid complexes forming with calcium.
Taken with plenty water with an upright position maintained for 30 mins after consumption (Prevents esophagitis).
Drug holiday bisphosphonates
When been taking bisphosphonates for 3 years (IV), or 5 years (oral).
What is Raloxifene?
Selective estrogen receptor modulator (SERM)
How do Raloxifene work? (4)
- Inhibits bone resorption
2. Reuding risk of vertebral fractures and increases bone density.
When is Raloxifene used?
Second-line treatment for
1.Post-menopausal women
Also reduces risk of breast cancer
Contraindication for raloxifene
- Pre-menopausal women (blocks estrogen and causes a decrease in bone density)
- Venothromboembolism
Normal T score
> -1
Osteopenia T score
-1 - -2.5
Osteoporosis T score
< -2.5
Risk factors of osteoporosis
-Female sex
-Increasing age
-Menopause
-Oral corticosteroids
-Smoking
-Alcohol
-Previous fragility fracture
-Parental history of hip fracture
-Rheumatological conditions, such as RA and
other inflammatory arthopathies
-Body mass index of less than 18.5 kg/m2
Why are women more at risk?
Decreased oestrogen production at menopause, which accelerates bone loss.
Target for osteoporosis treatment
Inhibit osteoclastic bone resorption, termed anti-responsive agents
Increase osteoblastic bone formations, such as parathyroid hormone
Non-pharmacological treatment
- Adequate calcium and vitamin D intake
- Exercise (weight bearing 30 mins, three times/week)
- Smoking cessation
- Fall prevention
- Reduction in alcohol intake
- Avoid drugs that can increase osteoporosis (steroids)
Bisphosphonates examples
Alendronic acid (alendronate)
Risedronate
Ibandronic acid
Zolendroninc acid
