Osteoporosis (MSK) Flashcards
Define osteoporosis.
- complex skeletal disease characterised by low bone density and micro-architectural defects in bone tissue
- results in increased bone fragility and susceptibility to fracture
What is the most common type of osteoporosis?
Primary osteoporosis (more common than secondary osteoporosis)
What are some causes of primary osteoporosis? (3)
- post-menopausal osteoporosis - decreased oestrogen leads to increased bone resorption due to increased osteoclast activity and decreased osteoblast activity
- senile osteoporosis - gradual loss of bone mass as patients age
- rheumatoid arthritis
What happens in post-menopausal osteoporosis?
Decreased oestrogen leads to increased bone resorption due to increased osteoclast activity and decreased osteoblast activity
What happens in senile osteoporosis?
Gradual loss of bone mass as patients age
What are some causes of secondary osteoporosis? (5)
- drug-induced: long term corticosteroid therapy, PPIs
- Cushing’s syndrome
- hyperthyroidism
- hyperparathyroidism
- hypogonadism
What drugs can cause osteoporosis? (2)
- long-term corticosteroid therapy
- PPIs
How does osteoporosis typically present?
Asymptomatic until fracture occurs
What are the clinical features of osteoporosis? (4)
- fragility fractures - pathological fractures caused by everyday activities or minor trauma
- back pain - vertebral fracture most common
- kyphosis (vertebral fracture)
- vertebral tenderness (vertebral fracture)
What type of fracture is most common in osteoporosis?
Vertebral fracture –> back pain, kyphosis, vertebral tenderness
But most vertebral fractures are subclinical or asymptomatic
What are some risk factors for osteoporosis? (8)
- prior fragility fracture
- female sex - postmenopause, secondary amenorrhoea
- white ancestry
- older age (F>50, M>65)
- low BMI
- malnutrition - low calcium and vitamin D
- glucocorticoid excess (steroid use)
- tobacco smoking
What is the gold standard investigation for osteoporosis?
DEXA scan (dual-energy x-ray absorptiometry) - measures T-score (bone mineral density)
What is T-score on a DEXA scan?
- bone density as a standard deviation compared to reference population of healthy young adults
- i.e. -2.5 = 2.5 SDs below that of an average healthy young adult
What T-score result on DEXA scan indicates osteoporosis vs osteopenia?
- osteoporosis: T-score </= -2.5
- severe/established osteoporosis: T-score </= -2.5 WITH fragility fracture(s)
- osteopenia: T-score -1 to -2.5
What is the difference between T-score and Z-score on DEXA scan (osteoporosis)?
- T-score is bone density compared to a healthy 30-year-old
- Z-score is adjusted for age, sex and ethnicity
In which patient is a DEXA scan not necessary in diagnosing osteoporosis?
Following a fragility fracture in women >/=75
What is the first line investigation for suspected osteoporotic vertebral fracture?
X-ray of the spine (NOT an MRI)
What is FRAX (osteoporosis)?
Estimates 10-year risk of fragility fracture
What will bone profile show in osteoporosis?
Normal - ALP, calcium, albumin, phosphate, PTH
What do we always check in a man with osteoporosis?
Testosterone
What are some differential diagnoses for osteoporosis? (6)
- multiple myeloma
- osteomalacia
- CKD bone and mineral disease (renal failure, creatinine and PTH high)
- primary hyperparathyroidism
- metastatic bone malignancy
- vertebral deformities
How do we diagnose osteoporosis?
DEXA scan:
- T-score </= -2.5 indicates osteoporosis
- T-score </= -2.5 WITH fragility fracture(s) indicates severe/established osteoporosis
What is the first-line management for osteoporosis?
Bisphosphonates (alendronate) - inhibit osteoclasts leading to reduced bone resorption
What other conditions can we use bisphosphonates to manage, other than osteoporosis? (3)
- hypercalcaemia
- Paget’s disease
- pain from bone metastases
What are some side effects of bisphosphonates (osteoporosis)? (3)
- oesophagitis/oesophageal ulcer - patients should take tablet on empty stomach 30min before breakfast with water, and remain upright for 30min to reduce mucosal irritation (taken once a week)
- osteonecrosis of the jaw
- atypical stress fractures especially of proximal shaft
When are bisphosphonates contraindicated in osteoporosis?
Poor kidney function (give denosumab or alternative instead)
What can you give if patients cannot tolerate side effects of bisphosphonates for osteoporosis?
Risedronate or denosumab
Denosumab: increases osteoblast activity = builds bone
How do we manage postmenopausal women with osteoporosis?
- bisphosphonates
- calcium and vitamin D supplementation (ergocalciferol, calcium)
- 2nd line - denosumab (PTH receptor agonist with antiresorptive agent)
How do we manage osteoporosis in men?
- bisphosphonate
- calcium and vitamin D supplementation
- testosterone
- 2nd line - teriparatide (PTH analogue with antiresorptive agent)
- alternative - denosumab (PTH receptor agonist with antiresorptive agent)
What other management is there based on cause of osteoporosis? (3)
- calcium and vitamin D supplementation (ergocalciferol) - if needed give before alendronate
- teriparatide (PTH analogue)
- avoid/minimise use of glucocorticoids
What is a complication of osteoporosis?
Fractures - hip, rib, wrist, femoral
