bone disorders Flashcards
what is active bone resorption driven by
osteoclasts
what is bone formation driven by
osteoblasts
what is bone like at 50 years
Decrease in trabecular thickness which is more pronounced for non load-bearing horizontal trabeculae
what is bone like at 80 years
- Decrease in number of connections between vertical trabeculae
- Decrease in trabecular strength
what factors affect bone loss
- sex hormone deficiency
- body weight
- genetics
- diet
- immobility
- diseases
- drugs
what are some modifiable risk factors for fractures
- BMD
- alcohol
- weight
- smoking
- physical inactivity
- pharmacological risk factors
who is assessed for fracture risk
- anyone over 50 with risk factors
- anyone under 50 with very strong clinical risk (early menopause and glucocorticoids)
what defines osteopenia
BMD >1 SD below the young adult mean but <2.5 SD below this value
what defines osteoporosis
BMD ≥ 2.5 SD below the young adult mean
what defines severe osteoporosis
BMD ≥2.5 SD below the young adult mean with fragility fracture
secondary causes of bone disease
- Endocrine e.g. hyperthyroidism, hyperparathyroidism, Cushing’s disease
- Gastrointestinal e.g. coeliac disease, IBD, chronic liver disease, chronic pancreatitis
- Respiratory e.g. CF, COPD
- Chronic kidney disease
drug treatments for osteoporosis
- Calcium & vitamin D supplementation
- Bisphosphonates
- Denosumab
- Teriparatide
- Romosozumab
- HRT
- SERMS (Selective Estrogen Receptor Modulators)
- Testosterone
what do bisphosphonates do
mainstay of treatment for osteoporosis
- prevent bone loss at all sites vulnerable to osteoporosis
- anti-resorptive agents
- injested by osteoclasts leading to cell death thereby inhibiting bone resorption
when is treatment considered with antiresorptive therapy
when T score is
how is zoledronic acid given
once yearly IV infusion for 3 years
-second line to bisphosphonates
what does denosumab
fully human monoclonal antibody that targets and binds with high affinity and specificity to RANKL
-This prevents activation of its receptor, RANK, inhibiting development and activity of osteoclasts, decreasing bone resorption and increasing bone density.
how is denosumab given
subcutaneous injection 6 monthly
what does teriparatide do
stimulates bone growth rather than reducing bone loss
-restricted to patients with severe osteoporosis as very expensive
what does romosozumab do
a monoclonal antibody that binds to and inhibits sclerostin
- increases bone formation and reduced bone resorption
- for postmenopausal women
what are corticosteroids effect on bone
- direct reduction of osteoblast activity and lifespan
- direct suppression of replication of osteoblast precursors
- direct reduction in calcium absorption
- indirect inhibition of gonadal and adrenal steroid production
what is Paget’s disease
- abnormal osteoclastic activity followed by increased osteoblastic activity
- abnormal bone structure with reduced strength and increased fracture risk
what does paget’s disease present with
- bone pain
- deformity
- deafness
- compression neuropathies
diagnosis of paget’s
Diagnose on XR; isotope bone scan shows the distribution of disease; biochemistry shows raised alkaline phosphatase with otherwise normal LFTs
treatment of paget’s disease
bisphophonates if pain not responding to analgesia
