Osteoporosis Flashcards
Osteoporosis Definition
Reduction in trabecular bone mass/density and disruption of bone architecture, resulting in porous bone with increased fragility and fracture risk
Osteopenia Definition
Refers to a less severe reduction in bone density than osteoporosis
Osteomalacia
Poor bone mineralisation leading to soft bones due to lack of Ca2+ (adult form of rickets)
Epidemiology
Female (esp after menopause)
50+
Caucasians + Asians more at risk
Risk factors (SHATTERED)
Steroids
Hyperthyroid/Hyperparathyroidism
Alcohol + smoking
Thin (Low BMI)
Testosterone (Low)
Early menopause (Low oestrogen)
Renal/ liver failure
Erosive + inflammatory disease
DMT1 or malabsorption
Aetiology (Primary + Secondary = MERCCCCM)
Primary:
- older age
Secondary:
- malignancy e.g. multiple myeloma
- endocrine conditions e.g. diabetes, Cushing’s
- rheumatological conditions
- chronic liver disease
- COPD
- CKD
- certain drugs: SSRIs, PPIs, anti-epileptics, anti-oestrogens
- malabsorption e.g. IBD,
Pathophysiology
During normal ageing, bone breakdown by osteoclasts increases and is not balanced by new bone formation by osteoblasts, resulting in a combination of:
- reduced bone mineral density (BMD), which can be measured by DEXA scan
- changes in bone composition architecture, size _ geometry
Bone remodelling depends on:
- PTH = promotes resorption when Ca2+ is low
- Calcitonin = release by thyroid when Ca2+ is high promoting bone formation
- Vit D = promotes Ca2+ absorption in the gut so increases serum Ca2+ promoting bone formation
The age when osteoporosis becomes apparent depends on
Peak bone mass (higher bone mass is protective)
The rate of bone loss
Signs + Symptoms
Osteoporosis is asymptomatic + will remain undiagnosed until a fragility fracture occurs
Evidence of acute fracture: from standing height or less
- Pain
- Acute bony deformity
- Inability to weight bare
Evidence of previous fractures:
- Kyphosis
- Chronic bony deformity
Common fragility fractures include:
- Vertebral crush, fracture,
- Distal wrist (Colles’ fracture)
- Proximal femur (falls)
Diagnosis
GOLD STANDARD = DEXA SCAN
- Dual energy XR absorptiometry
- Measures bone mineral density
- Yields T score (compares Px BMD to reference)
FRAX score = predicts the risk of a fragility fracture over the next 10 years
Vit D levels
Renal function
T score
Within 1 s.d.
+1 < T < -1 = normal, within 1SD
- 1 < T < -2.5 = Low BMD, OSTEOPENIA
T < - 2.5 = OSTEOPOROTIC
Treatment
FIRST LINE = BISPHOSPOHONATES
- Alendronic acid
- Zolendronic acid
+ Calcium + Vit D supplementation: Adcal D3
SECOND LINE =
- Denosumab: post menopausal women (inhibit RANKL)
- Raloxifene: post menopausal women
- Parathyroid hormone antagonist: teriparatide
Complications
Fractures
Chronic pain
Osteonecrosis of the jaw: bisphosphonate treatment
DVT/PE: raloxifene
