metabolic bone disease Flashcards
what is the role of osteoclasts
to break down bone
what is the role of osteoblasts
to build up bone
where is vitamin D produced
by the skin
where is vitamin D stored
in the liver
where is vitamin D activated
at the kidneys
what is the name of the vitamin D that has been activated by the kidneys
calcitrol
what is the role of calciferol
to increase the amount of calcium that is absorbed from the gut
what will happen is there is a calcium or vitamin D deficiency in children
rickets
what will happen if there is a calcium or vitamin D deficiency in adults
osteomalacia
what is the difference between rickets and osteomalacia
fusion of the epiphyseal plates
name some clinical signs of rickets
- stunted growth
- large abdomen
- large forehead
- bent out legs
- wide bones and joints
what is the cause of rickets
a deficiency in calcium or vitamin D in children
what is Paget’s disease
this is a disorder in which there is too much bone resorption and formation which leads to the formation of disordered bone
what is the treatment of rickets and osteomalacia
increased intake of calcium and vitamin D (if there is kidney failure you may need to give the patient activated vitamin D)
where is the mutation in Paget’s
on the loci of SQSTMI
what proportion of Paget’s is familial
15-30%
what are the symptoms of Paget’s disease
- long history of bone pain
- bone deformity
- excessive heat over the affected bone
- neurological problems (e.g. hearing loss) - Paget’s can occur in the skull bones
- may present with an osteosarcoma
what serum test will be raised in those with Paget’s
alkaline phosphatase
what is the treatment of Paget’s disease
SHOULD NOT BE TREATED IF ASYMPTOMATIC UNLESS IN THE SKULL
- IV bisphosphonate
what is osteogenesis imperfecta
this is a genetic disorder characterised by fragile bones - there are different types and prognosis depends on the type
what are the different types of osteogenesis imperfect
Type 1 = mild and potentially a few fractures
Type 2 = this is the most severe form and children usually die within weeks of being diagnosed
Type 3 = progressive deformity and bone dysplasia however not as severe as type 2
Type 4 = similar to type 1 but more severe
what are the clinical signs of osteogenesis imperfecta
- blue sclera
- scoliosis
- barrel chest
- defective tooth formation
- hearing loss
- ligamentous laxity
what is the management of osteogenesis imperfecta
- IV bisphosphonates
- surgery to repair fractures
- social adaptations
- genetic counselling
what is osteoporosis
this is a bone disease that is characterised by low bone mass and micro architectural deterioration - enhances bone fragility and fracture risk
what investigation can be used to diagnose osteoporosis
a bone DXA scan - a score of -2.5 SD or more from the normal adult healthy mean in post-menopausal woman
those with a score of -2.5 or more should be offered treatment and those with a score between -1 and -2.5 should be offered lifestyle advice (unless they have had a previous fracture - they should be offered treatment in this case)
when should someone be referred for a DXA scan
if they have a fracture risk assessment score of more than 10%
name the WHO fracture risk assessment tool
FRAX
name the fracture risk assessment tool that is most commonly used in Scotland
Q fracture risk assessment
name some conditions that can cause secondary osteoporosis
- bushings
- hyperthyroidism
- hyperparathyroidism
- hypoparathyroidism
- coeliac disease
- cystic fibrosis
- steroids, heparin and warfarin
how can you minimise someones osteoporotic fractures
- ensure good calcium and vitamin D status
- medications
- fall prevention strategies
- minimise the risk factors if possible
name the different types of medications that are used in the management of osteoporosis
- hormone replacement therapy
- selective oestrogen receptor modulator
- bisphosphonates
- teriparatide
- denosumab
what is the benefit of using hormone replacement therapy
it is effective on all bones
what are the side effects of hormone replacement therapy
- increased risk of blood clots
- increased risk of heart disease and stroke
- increased risk of breast cancer
SHOULD NOT BE USED A LONG TIME AFTER MENOPAUSE
what are the side effects of using selective oestrogen receptor modulators
- only works on vertebrae
- increased risk of blood clotting
- hot flushes if taken to close to menopause
what is the main treatment used in the management of osteoporosis
oral bisphosphonates
what are the side effects of using bisphosphonates
- oesphagitis
- uveitis
- femoral shaft fractures
- osteonecrosis of the jaw
- must have good renal function
- must have good calcium/vit D status
- drug holiday of 1-2 years needed after every 10 years
how do bisphosphonates work
bisphosphonates inhibit the osteoclasts and therefore prevent the breakdown of bone
what is teriparatide
this is an injection that works by building the bone up (this is the only anabolic treatment for osteoporosis)
what are the side effects of using teriparatide
- injection site reaction
- allergy
- cost
- hypercalcaemia
what is denosumab
a subcutaneous injection given every 6 months that reduces osteoclast bone resorption
this drug targets RANKL which usually inhibits the osteoblasts
what are the side effects of denosumab
- allergy
- hypocalcaemia
- osteonecrosis of the jaw
- atypical femoral shaft fractures
