metabolic bone disease Flashcards
paget’s disease
localised disorder of bone turnover
increased bone resorption followed by increased bone formation
leads to disorganised bone:
bigger, less compact
more vascular
more susceptible to deformity and fracture
why does someone get Paget’s disease
strong genetic component
environmental trigger: possibility of chronic viral infection within osteoclast
clinical features of Paget’s
always over 40, usually 60 bone pain: deep seated, worse at night bone deformity excessive heat over pagetic bone neuro complications e.g. nerve deafness long bones
presentation of paget’s disease
isolated elevation of serum alkaline phosphatase
bone pain and local heat
bone deformity or fracture
hearing loss
should paget’s disease be treated in asymptomatic patients
no evidence to treat asymptomatic Paget’s unless in skull or in area requiring surgical intervention e.g. hip replacement with pagetic pelvis
do not treat based on raised alkaline phosphatase alone
what is treatment for Paget’s
IV bisphosphonate therapy - one off zoledronic acid infusion
rarely requires another 3-5yrs after first
rickets and osteomalacia
severe nutritional vitD or calcium deficiency causes insufficient mineralisation
rickets = growing kid osteomalacia = adults when epiphyseal plates closed
what does vitamin D do for bone
stimulates absorption of calcium and phosphate from gut, and calcium and phosphate then become available for bone mineralisation
presentation rickets
stunted growth abnormal bony shape - splayed epiphyses large skull rickety shape bowed legs large abdomen odd shape ribs failure to thrive
osteomalacia presentation
elderly, house bound bone pain muscle weakness increased falls risk micro-fractures on X-ray and little holes skull (pepper pot skull)
treatment of osteomalacia/rickets
calcium and vitamin D supplements
oesteogenesis imperfecta
genetic abnormality of type 1 collagen fibres (connective tissue)
what is osteogenesis imperfecta
fragile bones from mild trauma and even acts of daily life
osteogenesis imperfecta defects in T1 collagen: 1
milder form
when child starts to walk, can present in adults
osteogenesis imperfecta defects in T1 collagen: 2
lethal by age 1
osteogenesis imperfecta defects in T1 collagen: 3
progressive deforming with severe bone dysplasia and poor growth
osteogenesis imperfecta defects in T1 collagen: 4
similar to 1 but more severe
other features of osteogenesis imperfecta
growth deficiency defective tooth formation hearing loss blue sclera scoliosis/barrel chest ligamentous laxity (hypermobility) easy bruising
management of osteogenesis
surgical: treat fractures
medical: fracture prevention, IV bisphosphonates
social: education, social adaptions
genetic: genetic counselling for parents and next generations
osteoporosis
metabolic bone disease characterised by low bone mass and micro-architectural deterioration of bone tissue
enhanced bone fragility and increase fracture risk
what DXA bone scan result would suggest osteoporosis
< -2.5SDs below the young adult mean in a post-menopausal woman
in osteoporosis what is fracture risk related to
bone density age BMI falls bone turnover
endocrine causes of osteoporosis
thyrotoxicosis (hyperthyroid) hyper and hypo-parathyroidism cushing's hyperprolactinaemia hypopituitarism low sex hormone levels
rheumatic causes of osteoporosis
rheumatoid arthritis
ankylosing spondylitis
polymyalgia rheumatic
gastroenterological causes of osteoporisis
IBD: UC, Crohn’s
liver diseases: chronic active hepatitis, alcoholic cirrhosis
malabsorption: CF, chronic pancreatitis, coeliac
medications which cause osteoporosis
steroids PPI enzyme inducting antiepileptic medications aromatase inhibitors GRH inhibitors warfarin
how to prevent osteoporotic fractures
minimise risk factors: stop smoking, minimise alcohol
ensure good Ca and VitD status
falls prevention
manage medications eg. steroids
what medications may help with osteoporosis
HRT selective oestrogen receptor modulator(raloxifene) bisphosphonates denosumab teriparatide
side effects of HRT
increased risk blood clots, breast cancer, heart disease + stroke
negative effects of selective oestrogen receptor modulators
hot flushes in taken close to menopause
increased clotting risk
lack protection at hip site
what is main Rx osteoporosis
bisphosphonates (oral)
how do bisphophonates work
poison osteoclasts
side effects of bisphophonates
oesophagitis
iritis/iveitis
not safe eGFR<30mls/min
denosumab
monoclonal antibody against RANKL
reduces osteoclatic bone reabsorption
osteoporosis risk factors
steroids smoking low BMI post-menopausal/early menopause age alcohol previous fractures
