Metabolic Bone Disease Flashcards
with a diagram describe bone remodelling
see notes
with a diagram show the factors stimulating osteoblast expression of RANK ligand
see notes
what is paget’s disease of the bone?
Paget’s of the bone is a localised disorder of bone turnover. It results from increased bone resorption followed by an increase in bone formation.
clinical features of paget’s disease of the bone
disorganised bone: bigger, less compact, more vascular and more susceptible to deformity and fracture
what % of paget’s disease of the bone are familial?
15-30%
name the important loci in paget’s disease of the bone
SQSTMI
presentation of paget’s disease of the bone
> 40
bone pain
occasionally : bone deformity, excessive heat over the pagetic bone or by neurological complications such as nerve deafness
isolated serum ALP - most common
bone pain, local heat, bone deformity or fracture, hearing loss
treatment of paget’s disease of the bone
IV bisphosphonates
severe nutritional vitamin D or calcium deficiency causes:
insufficient mineralisation and thus rickets in growing child and osteomalacia in adult
function of vitamin D
Vitamin D stimulates the absorption of calcium and phosphate from the gut and calcium and phosphate then become available for bone mineralisation. Muscle function is also impaired in low vitamin D states.
symptoms of osteomalacia
bone pain
muscle weakness
increased falls risk
what is osteogenesis imperfecta?
This is a genetic disorder of connective tissue characterised by fragile bones from mild trauma even acts of daily life. There are other non-bone clinical features to consider. There is a broad presentation ranging from prenatally fatal to those only presenting in 40s with early osteoporosis.
where are the defects in osteogenesis imperfecta?
type 1 collagen
features of the 4 most common types of osteogenesis imperfecta
- Milder form – when child starts to walk and can present in adults
- Lethal by age 1
- Progressive deforming with sever bone dysplasia and poor growth
- Similar to type 1 but more severe
other features of osteogenesis imperfecta
- Growth deficiency
- Defective tooth formation (dentigenesis imperfecta)
- Hearing loss
- Blue sclera
- Scoliosis/barrel chest
- Ligamentous laxity
- Easy bruising
management of osteogenesis imperfecta
• Surgical o Treat fractures • Medical o Prevent fractures o IV bisphosphonates • Social o Educational and social adaptation • Genetic o Counselling for parents and next generation
define 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. A result on DXA bone scanning <2.5 SDs below the young adult mean in a post-menopausal woman (T-score)
what is the risk of fracture in osteoporosis related to?
age
BMD
falls
bone turnover
describe the Q fracture tool
• Developed in 2009 from large primary care populations in the UK
• Applicable for those aged 30-85, men and women
• Contains multiple variables including:
o CV risk
o Falls
o TCA
• Does not have the ability to add BMD
• Some of the variables and risks cannot be altered by osteoporotic medications
Fracture risk assessment tools indicate whether someone is at risk of osteoporosis or not. If the risk is
considered significant (normally defined as a >10% risk of osteoporotic fracture over 10 years) the
individual should be referred for a DXA scan (dual energy x-ray absorptiometry). All who are on oral
steroids or suffer from a low trauma fracture should be referred for a DEXA scar regardless of their
fracture risk percentage.
how many women will have an osteoporotic fracture before they die?
1 in 2
how many men will have an osteoporotic fracture/
1 in 5
causes of osteoporosis: endocrine
thyrotoxicosis hyper and hypoparathyroidism Cushing's hyperprolactinaemia hypopitutarism low sex hormone levels
causes of osteoporosis: rheumatic
RA
ankylosing spondylitis
polymyalgia rheumatica
causes of osteoporosis: GI
inflammatory diseases e.g. UC and Crohn’s
liver diseases: PBC, CAH, alcoholic cirrohsis, viral cirrhosis
malabsoprtion: CF, chronic pancreatitis, coeliac, whipples disease, short gut syndromes, ischaemic bowel
causes of osteoporosis: medications
o Steroids o PPI o Enzyme inducting antiepileptic medications o Aromatase inhibitors o GnRH inhibitors o Warfarin
prevention of osteoporotic fractures
minimise risk factors ensure good calcium and vit D status falls prevention HRT bisphosphonates Denosumab teripartide
SE of HRT
• 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 large gap from menopause
• Selective oEstrogen Receptor Modulator (SERMS)
o Raloxifene
o No effect on non-vertebral fracture rates
o Hot flushes if taken close to menopause
o Increased clotting risks
o Lack of protection at hip site
discuss bisphosphonate use in osteoporosis
• Main Tx option • Oral generally first line • Adequate renal function required • Adequate calcium and vit D • Good dental health and hygiene advised o Notify dentist o Encourage regular check-ups/well-fitting dentures • Side effects o Oesophagitis o Iritis/uveitis o Not safe when eGFR <30 mls/min o ONJ (osteonecrosis of jaw) o Atypical femoral shaft fractures • Drug holiday for 1-2 years usually after 10 years use
describe denosumab in osteoporosis
• Monoclonal antibody against RANKL • Reduces osteoclastic bone resorption • SC injection every 6 months • Safer in patients with significant renal impairment than bisphosphonates • Side effects o Allergy/rash o Symptomatic hypocalcaemia if given when vitamin D deplete o ?ONJ o ?atypical femoral shaft fractures
SE of teriparatide
o Injection site irritation
o Rarely hypercalcaemia
o Allergy
o cost
