Disorders of bone health Flashcards
What is osteoporosis?
Progressive systemic skeletal disease characterised by low bone mass and micro-architectural deterioration of bone tissue with a consequent increase in bony fragility and susceptibility to fracture
What cell is overactive in osteoporosis?
Osteoclastic activity is higher than osteoblast activity leading to net bone loss
What regulates bone loss?
Sex hormone deficiency Body weight Genetics Diet Immobility Diseases Glucocorticoids and aromatase inhibitors
What are common osteoporotic fracture sites?
NOF
Vertebral bodies
Distal radius
Humeral neck
How is bone density assessed?
DEXA scan
Which areas are assessed in a DEXA scan?
Hip
L1-4
What is the T score?
A T-score shows how much your bone density is higher or lower than the bone density of a healthy 30-year old adult
What is the Z score?
Current bone density with those of your age, gender and weight
What is osteopenia?
BMD more than 1 DS below the young adult mean but less than 2.5 SD below
What is osteoporosis?
BMD more than 1.5 DS below the young adult mean
Who should be referred for a DEXA scan?
Patients over 50 with low trauma fracture
Increased risk of fracture based on risk factors using Qfracture or FRAX
What are modifiable risks for fragility fractures?
BMD Alcohol Weight Smoking Physical activity Pharma risk factors
What should be in the work up of suspected osteoporosis?
U+Es, LFTs, bone biochem, FBC, PB, TSH Coeliac antibodies Testosterone 25OH vit D PTH
What are secondary causes of osteoporosis?
Endocrine: hyperthyroidis, hyperparathyroidism, cushings
GI: coeliac, IBD, chronic liver disease, chronic pancreatitis
Resp: CF, COPD
CKD
What drug treatments are available in the treatment of osteoporosis?
Calcium and vit D supplements Bisphosphonates Denosumab Teriparatide HRT SERMS Testosterone
How much calcium should be in the diet?
700mg
Post menopausal women should aim for 1000mg to reduce fracture risk
What is the most of action of bisphosphonates?
Osteoclast cell death to prevent resorption of bone
Prevents bone loss
Reduces the risk of hip and spine fractures
How long should bisphosphonates be given for?
5 years (10y if vertebral fracture) Long term concerns: osteonecrosis of the jaw, oesophageal Ca, atypical fractures
What should be given in the case of unacceptable GI reactions to bisphosphonates orally?
Once yearly IV infusion of zoledronic acid
5mg in 100ml NaCl over 15 mins
What is denosumab?
Monoclonal antibody that targets and binds with high affinity and specificity to RANKL - prevents activation of its receptor, RANK, inhibiting development and activation of osteoclasts
What are the adverse effects of denosumab?
Hypocalcaemia
Eczema
Cellulitis
How is denosumab given?
Subcut injections 6 monthly
What is teriparatide?
Recombinant parathyroid hormone which stimulates bone growth
What is the direct action of corticosteroids on bone health?
Reduction of osteoblast activity and lifespan
Suppression of replication of osteoblast precursors
Reduction in calcium absorption
What are the indirect effects of corticosteroids on bone?
Inhibition of gonadal and adrenal steroid production
What is paget’s disease?
Abnormal osteoclastic activity followed by increased osteoblastic activity leading to abnormal bone structure with reduced strength and increased fracture risk
What bones will paget’s disease affect?
Long bones
Pelvis
Lumbar spine
Skull - hearing loss
What will pagets disease present as?
Bone pain Deformity Deafness Compressive neuropathies Osteosarcoma is a rare complication
How is paget’s disease diagnosed?
Isotope bone scan
Biochem: isolated raised alk phos (sign of osteoblastic activity)
How is pagets disease treated?
Bisphosphonates
Analgesia
What causes osteogenesis imperfecta?
Secondary to mutations of type 1 collagen genes
What is the mode of inheritance of OI?
Autosomal dominant inheritance
What other signs bar bones does OI show?
Blue sclera
Dentinogenesis imperfecta
How can OI present?
Fractures in childhood - important differential for NAI
How is OI managed?
Fracture fixation
Surgery to correct
Bisphosphonates
