A.12 Osteoporosis Flashcards
A.12 Osteoporosis
define
loss of trabecular and cortical bone mass which leads to bone weakness and increased susceptibility to fractures
A.12 Osteoporosis
Epidemiology
Sex: ♀ > ♂ (∼ 4:1)
Age of onset: 50–70 years
A.12 Osteoporosis
Etiology of Primary Osteoporosis
Type I (postmenopausal osteoporosis): postmenopausal women
- Estrogen stimulates osteoblasts and inhibits osteoclasts.
- The decreased estrogen levels following menopause lead to increased bone resorption.
Type II (senile osteoporosis): gradual loss of bone mass as patients age (especially > 70 years) - Osteoblast activity decreases, leading to less osteoid production.
Idiopathic osteoporosis
- Idiopathic juvenile osteoporosis
- Idiopathic osteoporosis in young adults
A.12 Osteoporosis
Etiology of Secondary Osteoporosis
Drug-induced/iatrogenic
Most commonly due to systemic long-term therapy with corticosteroids (e.g., in patients with autoimmune disease)
Long-term therapy involving:
- Anticonvulsants (e.g., phenytoin, carbamazepine)
- L-thyroxine
- Anticoagulants (e.g., heparin)
- Proton pump inhibitors
- Aromatase inhibitors (e.g., anastrozole, letrozole)
- Immunosuppressants (e.g., cyclosporine, tacrolimus)
- Androgen deprivation therapy (ADT)
Endocrine/metabolic:
- hypercortisolism
- hypogonadism
- hyperthyroidism, hyperparathyroidism, renal disease
Multiple myeloma
A.12 Osteoporosis
Risk Factors
- Excessive alcohol consumption
- Cigarette smoking
- Immobilization or inadequate physical activity
- Malabsorption (e.g., celiac disease), malnutrition (e.g., diet low in calcium and vitamin D), anorexia
- Low body weight
- Family history of osteoporosis
- Personal history of fracture
A.12 Osteoporosis
clinical
Mostly asymptomatic
- Fragility fractures: pathological fractures that are caused by everyday-activities (e.g., bending over, sneezing) or minor trauma (e.g. falling from standing height)
- Common locations of major osteoporotic fractures: vertebral (most common) > femoral neck > distal radius (Colles fracture) > other long bones (e.g., humerus)
- Vertebral compression fractures
Commonly asymptomatic but may cause acute back pain and possible point tenderness without neurological symptoms
Multiple fractures can lead to decreased height and thoracic kyphosis.
A.12 Osteoporosis
Screening
Screening is recommended in:
- Women ≥ 65 years of age
- Postmenopausal women < 65 years of age with ≥ 1 risk factor for osteoporosis
- Individuals with a history of low-trauma fracture after 50 years of age
A.12 Osteoporosis
DX
Assess BMD and estimate the risk of major osteoporotic fracture.
The diagnosis is confirmed if any of the following diagnostic criteria for osteoporosis are fulfilled.
- T-score ≤ -2.5 standard deviations (SDs) on dual-energy x-ray absorptiometry (DXA)
- T-score -1 to -2.5 SD in patients at increased risk of major osteoporotic fracture
History of a major osteoporotic fragility fracture (regardless of BMD)
Once confirmed:
- Consider screening all patients for common causes of secondary osteoporosis.
- Evaluate high-risk patients for vertebral fractures.
A.12 Osteoporosis
Bone mineral density (BMD) assessment
Preferred modality: dual-energy x-ray absorptiometry
Postmenopausal women and men > 50 years of age:
- BMD is calculated using the T-score.
- T-score ≤ -2.5 SD indicates osteoporosis
- T-score -1 to -2.5 SD indicates osteopenia
- T-score ≥ -1 SD is normal
DXA evaluates bone quantity. The trabecular bone score uses data from DXA images to evaluate bone quality and may sometimes be used to further stratify fracture risk
A.12 Osteoporosis
Labs
Routine studies
- CBC, CMP, PTH, phosphate, and serum 25-hydroxyvitamin D
- 24-hour urine to measure calcium, creatinine, and sodium levels
Additional studies:
- Evaluate for specific etiologies of secondary osteoporosis as guided by clinical assessment (e.g., celiac antibodies, TSH, myeloma screen).
- Consider BTMs to assess fracture risk and monitor treatment response.
Findings
- Primary osteoporosis: Serum calcium, phosphate, and parathyroid hormone (PTH) levels are usually normal
A.12 Osteoporosis
Pharma TX
Treatment: patients who fulfill any of the diagnostic criteria for osteoporosis
Prevention: patients with osteopenia and an increased probability of a major osteoporotic fracture in the next 10 years (as determined on a clinical risk assessment tool such as the FRAX)
General principles
- Bisphosphonates are preferred first-line agents.
Consider nonbisphosphonates as first-line alternatives in certain situations or as second-line agents if bisphosphonate therapy is unsuccessful or not tolerated.
A.12 Osteoporosis
Bisphosphonates
Mechanism of action: inhibition of osteoclasts, which are involved in bone resorption
Agents:
Alendronate
Risedronate
Ibandronate
A.12 Osteoporosis
Other TX
Denosumab
Patients with impaired renal function
MOA: Monoclonal antibody against the receptor activator of nuclear factor-κB ligand (RANKL)
Targets RANKL by mimicking osteoprotegerin → interference in osteoclast maturation → ↓ osteoclast activity
A.12 Osteoporosis
Preventative Measures
Optimize calcium and vitamin D intake
Treat vitamin D deficiency.
Encourage physical activity, including strength (resistance) and balance training
