Osteoporosis and Metabolic Bone Disease Flashcards
What is osteoporosis?
A metabolic bone disease characterised by low bone mass and micro-architectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk
What is fracture risk related to?
Age
Bone mineral density
Falls
Bone turnover
What is referral for DXA scanning based on?
FRAX or Q Fracture score of > 10% fracture risk at any site over next 10 years, according to 2003 SIGN guidelines
What is the treatment threshold in terms of fracture risk?
Fracture risk around 20% 10 year risk would be the treatment threshold
What are the features of Q Fracture?
Developed in 2009 from large primary care populations in UK
Applicable for those aged 30-85, men and women
Contains multiple variale including CVS risks, falls and TCA
Does not have the ability to add BMD
Some of the variables and risks cannot be altered by osteoporotic medications
What are the endocrine causes of secondary osteoporosis?
Hyperthyroid Hyperparathyroid Hypoparathyroid GH deficiency Hyperprolactinaemia Cushing's
What are the malabsorption causes of secondary osteoporosis?
Coeliac disease
CF
What malignancy causes secondary osteoporosis?
Myeloma
What are the rheumatic causes of secondary osteoporosis?
RA
Ankylosing spondylitis
PMR
What are the drugs that cause secondary osteoporosis?
Steroids Heparin Warfarin Anticonvulsants PPIs GnRH inhibitors
What are the causes of amenorrhoea, which can result in secondary osteoporosis?
Anorexia nervosa
Early menopause
Primary ovarian failure
What is involved in osteoporotic fracture prevention?
Minimise risk factors
Ensure good calcium and vitamin D status
Fall prevention strategies
Medications
What are the investigations used to confirm the diagnosis of osteoporosis?
Measure BMD via DXA hip and spine
If result is normal (T score above -1) then reassure and give lifestyle advice
If result indicates osteopenia (T score -1 to -2.5 then give lifestyle advice or treat if there has been a previous fracture
If result indicates osteoporosis (T score below -2.5) then give lifestyle advice and offer treatment
What are the types of drugs used in prevention and treatment of osteoporosis?
HRT Selective Oestrogen Receptor Modulators Bisphosphonates Teriparatide Denosumab
What are the risks of HRT treatment?
Increased risk of blood clots
Increased risk of breast cancer with extended use into late 50s/early 60s
Increased risk of heart disease and stroke if used after a large gap from menopause
What are the disadvantages of selective oestrogen receptor modulator treatment?
Hot flushes if taken close to menopause
Increased clotting risks
Lack of protection at hip site
What is the main treatment option for osteoporosis?
Bisphosphonates - oral bisphosphonates generally the first line of treatment
What is required for bisphosphonate treatment?
Adequate renal function
Adequate calcium and vitamin D status
Good dental health and hygiene advised
What bisphosphonates inhibit osteoclasts?
Nitrogen containing bisphosphonates
What are the potential side effects of bisphosphonates?
Oesophagitis
Iritis/uveitis
Atypical femoral shaft fractures
What is teriparatide?
Recombinant form of parathyroid hormone
What are the side effects/disadvantages of teriparatide?
Injection site irritation
Hypercalcaemia (rarely)
Allergy
Cost
What is denosumab?
Monoclonal antibody against RANKL
Reduces osteoclastic bone resorption
How is denosumab administered?
Subcutaneous injection every 6 months
In what patients is denosumab safer than bisphosphonates?
Patients with significant renal impairment
What are the side effects of denosumab?
Allergy
Rash
Symptomatic hypocalcaemia if given when vitamin D deplete
Possible ONJ
Possible atypical femoral shaft fractures
What does severe nutritional vitamin D or calcium deficiency cause?
Insufficient mineralisation and rickets in a growing child, osteomalacia in an adult (where the epiphyseal lines are closed
What does vitamin D stimulate?
Absorption of calcium and phosphate from the gut, so calcium and phosphate become available for bone mineralisation
What happens to muscle function in low vitamin D states?
Muscle function is impaired
What is Paget’s disease? What happens in this disease?
Localised disorder of bone turnover
Increased bone resorption followed by increased bone formation
Leads to disorganised bone - bigger, less compact, more vascular and more susceptible to fracture
What percentage of cases of Paget’s disease are familial?
15-30%
Mutations in what loci have been associated with Paget’s disease?
Loci of SQSTM1
What are the symptoms of Paget’s disease?
Patients > 40 years
Bone pain
Occasionally presents with bone deformity, excessive heat over the Pagetic bone, or by neurological complications
What is the presentation of Paget’s disease?
Isolated elevation of serum alkaline phosphatase - commonest presentation
Bone pain and local heat
Bone deformity or fracture
Hearing loss
Rare - development of osteosarcoma in affected bone
What is the treatment of Paget’s disease?
No evidence to support treatment of asymptomatic disease, unless in the skull or in an area requiring surgical intervention
Should not be treated based on raised alkaline phosphatase alone
IV bisphosphonate therapy, one off IV xoledronic acid
What is osteogenesis imperfecta?
Genetic disorder of connective tissue characterised by fragile bones from mild trauma and acts of daily life
What is the clinical range of osteogenesis imperfecta?
Broad - from those that are prenatally fatal to those presenting in 40s with early osteoporosis
What defect results in osteogenesis imperfecta?
Defects in type 1 collagen - 8 different types but the first 4 are the most common
What are the features of type 1 osteogenesis imperfecta?
Milder form, presents when child starts to walk, but can present in adults
What are the features of type 2 osteogenesis imperfecta?
Lethal by age 1
What are the features of type 3 osteogenesis imperfecta?
Progressive deforming with severe bone dysplasia and poor growth
What are the features of type 4 osteogenesis imperfecta?
Similar to type 1 but more severe
What are the signs and symptoms of osteogenesis imperfecta?
Growth deficiency Defective tooth formation (dentigenesis imperfecta) Hearing loss Blue sclera Scoliosis Barrel chest Ligamentous laxity Easy bruising
What is the management of osteogenesis imperfecta?
Surgical - to treat fractures
Medical - fracture prevention, IV bisphosphonates
Social - educational and social adaptations
Genetic - genetic counselling for parents and next generation
