Osteoporosis & osteomalacia Flashcards
Define osteoporosis
Skeletal disorder of low bone mass, with normal mineralisation. This leads to enhanced bone fragility and increased fracture risk.
WHO: Bone density of 2.5 standard deviations below the young health adult mean value (T-score ≤ -2.5)
What is an osteoporotic fracture?
A fragility fracture (fracture following a fall from standing height or less) occuring as a consequence of osteoporosis
Characteristically in the wrist, spine, and hip
Differentiate between type 1 and 2 osteoporosis
- Type 1 (postmenopausal):
- Loss of osteoclast inhibition; increased bone resorption
- Commoner in women, aged 50-70
- Primarily affects spongy bone
- Wrist and vertebral fractures; crush fractures
- Type 2 (senile):
- Reduced osteoblast function; insufficient mineralisation
- Commoner in women, aged 70+
- Equally affects spongy and cortical bone
- Hip and vertebral fractures; long bone fractures
Describe the lifetime changes in bone mineral density
- Peak bone mass achieved between 20-30yr
- Bone mass maintained up to 40yr
- Loss of bone mass from 40yr onwards
- Accelerated loss in women around time of menopause
List five risk factors for osteoporosis
- Reduce BMD:
- Diabetes; hyperthyroidism; hyperparathyroidism
- Malabsorption eg. IBD; Coeliac disease; pancreatitis
- CKD; cirrhosis; COPD
- Menopause
- Immobility; BMI <18.5
- Other:
- Increasing age
- Oral corticosteroids; PPIs; SSRIs; AEDs
- Smoking; alcohol
- RA and other inflammatory arthropathies
- PMHx or FHx of hip fracture
Which patients are high-risk osteoporosis?
- Age >75
- Glucocorticoid therapy
- Previous hip or vertebral fracture
- Further fracture on treatment
- High FRAX score T score below -2.5 after treatment
How may osteoporosis present?
Asymptomatic condition that presents with fragility fractures:
- 50yr+ Colle’s fracture: Fall on outstretched hand
- 60yr+ Vertebral fracture
- 70yr+ Hip fracture
What can be used to assess osteoporotic fracture risk?
FRAX tool or QFracture
What investigation is used to diagnose osteoporosis?
DEXA scan: Gold standard for osteoporosis
- T-score: SDs away from a young person of same gender and ethnicity
- Z-score: SDs away from an age, weight, sex matched population
Post-menopausal women who suffer a fracture should be given bisphosphonates, do not require a DEXA scan
What are the indications for DEXA scanning?
- Aged >50 with a history of fragility fracture
- Aged <40 with a major risk factor for fragility fracture
- High 10-year fragility fracture risk using QFracture or FRAX
Outline the WHO classification of DEXA T-score
- Normal: Above -1
- Osteopenia: -1 to -2.5
- Osteoporosis: Below -2.5
- Established: addition of 1+ associated fragility fracture
Outline the management of osteoporosis
- Lifestyle:
- Smoking cessation; reduced alcohol consumption
- Weight-bearing and balance exercises
- Calcium and vitamin D rich diet
- Home-based fall-prevention programme
-
Bisphosphonate eg. alendronate or risedronate
- Specialist options eg. zoledronic acid; denosumab
- Vitamin D supplements if calcium intake inadequate
- Consider HRT if premature menopause (<40y)
What patient advice needs to be given regarding how to take oral bisphosphonates?
- Taken 30 minutes prior to eating and drinking
- With a large drink of water
- Whilst standing or sitting upright
Name one contraindication of Alendronate
eGFR <35
Pregnancy
Name three side-effects of bisphosphonates
- Gastritis; abdominal distension, pain, dyspepsia
- Photosensitivity
- Oesophagitis; oesophageal ulcers (esp alendronate)
- Steven-Johnson syndrome/Toxic epidermal necrolysis
- Osteonecrosis of the jaw; and the external auditory canal
- Atypical femoral fractures
Describe the production of vitamin D
Name two signs of rickets
- Craniotabes: thin deformed skull
- Rickety rosary: beading of ribs and wrists
- Lower limb deformities: varus/valgus deformity
