Osteoporosis and Metabolic Disease Flashcards
Definition of osteoporosis
a metabolic bone disease characterised by low bone mass and micro architectural deterioration of bone tissue, leading to enhanced bone frailty and a consequent increase in fracture risk
Causes of osteoporosis
thyrotoxicosis hyper/hypo parathyroidism cushings hyperprolactinaemia hypopituitarism low sex hormone levels RA ankylosing spondylitis polymyalgia rheumatica UC/chrones liver diseases - PBC, CAH, alcoholic cirrhosis, viral cirrhosis (Hep C) malabsorption - CF - Chronic pancreatitis - coeliac disease - whipples disease - short gut syndrome - ischaemic bowel medications - steroids - PPI - enzymes inducing antiepileptic medications - aromatase inhibitors (used in breast cancer) - GnRH inhibitors - Warfarin
Risk of fractures in osteoporosis
age
BMD
Falls
Bone turnover
What assessment in done to indicate whether someone is at risk of osteoporosis?
FRAX - fracture risk assessment tools
What is considered as a significant risk of fracture in osteoporosis?
> 10 % risk of osteoporotic fracture over 10 days
What should be done if a patient has significant risk of fracture?
Be referred for a DXA scan (dual energy X ray absorptiometry)
Who should be sent for a DXA scan in osteoporosis regardless of their %?
Oral steroids
suffer a low trauma fracture
Prevention of osteoporotic fractures
minimise risk factors
ensure good calcium and vit D status
falls prevention strategies
medications
Treatment of osteoporosis
HRT SORMR (selective oestrogen receptor modulator) - raloxifene bisphosphonates - MAIN TREATMENT Denosumab Teriparatide
Side effects of HRT
Increased risk of
- blood clots
- breast cancer with extended use into 50s/60s
- heart disease and stroke if used after a large age gap from menopause
Side effects of SERMS
Hot flushes if close to menopause
increased clotting risks
lack of protection at hipsite
First line of treatment for osteoporosis
Oral biphosphonates
Side effects of biphosphonates
oesophagitis
iritis/uveitis
ONJ
atypical femoral shaft fractures
What needs to be done In long term use of bisphosphonates?
drug holiday for 1 - 2 years
usually after 10 years oral biphosphonates
What does denosumab do?
reduces osteoclast bone resorption
How is denosumab taken?
SC injection every 6 months
Side effects of denosumab
allergy/rash
symptomatic hypocalcaemia if given when vit D deplete
What is teriparatide?
intermittent human parathyroid hormone
side effects of teriparatide
injection site irritation
rarely hypercalcaemia
allergy
cost
What do osteoblasts do?
Fill in pit produced by the osteoclasts
controlling cell
What do osteoclasts do?
secretes acid into bone environment to dissolve it and produces a pit in the bone
Bone remodelling time; adult vs child
adult - very slow
child - really fast
What controls osteoblasts?
Parathyroid hormone
Vitamin D
What are the bone active hormones?
parathyroid hormone
vitamin D
When does accelerated loss of bone mass begin?
menopause
What is the difference between rickets and osteomalacia?
They are both the same condition, just occur at different times
When does osteomalacia occur?
After the epiphyseal plates fuse
When does rickets occur?
Before the epiphyseal plates fuse
What casues rickets/osteomalacia?
severe nutritional vit D or calcium deficiency
Presentation of rickets
Stunted growth odd curve to spine or back large forehead odd shaped ribs and breast bones large abdomen wide bones wide ankles odd shaped legs failure to thrive
Osteomalacia symptoms
bone pain muscle weakness increased falls risk dont get deformities you can visualise microfractures of the bone
Definition of osteogenesis imperfecta
Genetic disorder of connective tissue characterised by fragile bones from mild trauma and even acts of daily life
Pathology of osteogenesis imperfecta
Defects in type I collagen
Defective osteoid formation due to congenital inability to produce adequate intercellular substances like osteoid, collagen and dentine
Failure of maturation of collagen in all of the connective tissues
Presentation of osteogenesis imperfecta
early osteoporosis growth deficiency defective tooth formation - dentigenesis imperfecta hearing loss blue sclera scoliosis/barrel chest ligamentous laxity easy bruising
Treatment of osteogenesis imperfecta
surgical - to treat fractures
medical - to prevent fractures
- IV bisphosphonates
educational and social adaptations
Paget’s disease of bone definition
Localised disorder of increased and uncontrolled bone turnover
Pathology of Paget’s disease of bone
Excessive osteoclastic resorption followed by increased osteoblastic activity
increased bone resorption by increased bone formation
not occurring in a structured fashion
Leads to disorganised bone
- bigger
- less compact
- more vascular
- more susceptible to deformity and fracture
leading to pulsating pain
Causes of paget’s disease of bone
Strong genetic component (15-30%) Restricted geographical distribution - those of Anglo-Saxon origins Environmental trigger - possibly of chronic viral infection with osteoclast
Symptoms of pagets disease of bone
> 40 y/o
Bone pain
occasionally bone deformity
excessive heat over pagetic bone
neurological complications e.g. nerve deafness
ISOLATED ELEVATION OF SERUM ALKALINE PHOSPHATE (ALP)
Calcium and phosphate typically normal
bowed bone tibia
broad forehead
rarely the development of osteosarcoma in affected bone
Where can you get pagets disease of bone?
can be localised i.e. in one bone or
can be widespread i.e. in bits all over the body
never affects the WHOLE skeleton
Who with pagets is treated?
Bone pain
Skull or long bone deformity
Fracture
Periarticular pagets
Most common areas to get pagets
Skull
Spine
Pelvis
Long bones of the lower extremities
Predisposing factors to pagets
Increasing age
Male
Northern latitude
FH
What % of patients with pagets disease are symptomatic?
5%
Other markers of bone turnover
PINP
CTx
NTx
Urinary hydroxyproline
Is pagets easy to treat?
Yes
Treatment of pagets disease
IV biphopshonates
How do bisphosphonates work?
Analogues of pyrophosphate - inhibit osteoclasts by reducing recruitment and promoting apoptosis
Management of patients at risk of corticosteroid induced osteoporosis - the two groups
- Patients > 65 y/o or those who have previously had a fragility fracture SHOULD be offered bone protection
- Patients < 65 y/o should be offered a BONE DENSITY SCAN with further management dependent on this
Results of the bone density scan in the < 65s and their treatment
T > 0 = Reassure
T 0 to -1.5 = Repeat bone density scan in 1 - 3 years
T < - 1.5 = Offer bone protection
Subtypes of osteogenesis imperfecta
Type I - Type 4
Type I osteogenesis imperfecta
Collagen normal quality but insufficient quality
Type II osteogenesis imperfecta
Poor collagen quality and quantity
Type III osteogenesis imperfecta
Collagen poorly formed
Normal quantity
Type IV osteogenesis imperfecta
Sufficient collagen quantity but poor quality
What is osteopetrosis?
Bones become harder and more dense which can lead to pathological fractures
Who gets osteopetrosis?
Young adults
Inheritance of osteopetrosis
AR
What does radiology of osteopetrosis show?
Lack of differentiation between the cortex and the medulla described as - MARBLE BONE
What blood tests is osteoporosis associated with?
NORMAL blood tests (Ca, P, PTH, ALP)
What is the Z score of DEXA scans adjusted for?
Age
Gender
Ethnic factors
What do the T and Z scores of the DEXA scan look at?
T - bone density compared to a healthy 30 year old
Z - compares your bone density to someone your age and body size
