Metabolic Bone Disease Flashcards
What is Paget’s disease
Disorder of bone turnover
There is increased bone resorption followed by increased bone formation leading to disorganised bone
What is bone like in Paget’s (4)
Bigger
Less compact
More vascular
More susceptible to deformity and fracture
What percentage of Paget’ is familial - what is the gene involved
15-30%
Loci of SQSTMI
Anglo-Saxon origins
Presentation of Paget’s (5)
Bone pain - blood gives deep pulsating pain
Bone deformity
Excessive heat over Pagetic bone
Neurological complications - i.e. nerve deafness
Development of osteosarcoma in affected bone (rare)
What age group does Paget’s occur in
Over 40s
What scan is used for Paget’s - what does it show
Isotope bone scan shows area of dense bone
What bone and liver enzyme is affected by Paget’s and how
Serum alkaline phosphatase is elevated
differential of Paget’s
metastatic cancer
When is treatment for Paget’s indicated
If in skull or area requiring surgical intervention - do not treat based on a raised AlkPhos alone
What medication is used for Paget’s
IV bisphosphonate
what is a type of bisphosphonate used for Pagets
Zoledronate injection (one off)
What is the difference between rickets and osteomalacia
Ricket’s is before the epiphyseal plates have fused
Osteomalacia is after the epiphyseal plates have fused
Clinical presentation of rickets (4)
Stunted growth
Bandy legs (wide)
Large skull (fontanelles do not fuse)
Failure to thrive
Clinical presentation of osteomalacia (5)
No visible deformity Microfractures Bone pain Muscle weakness Increased fall risk
Who is most at risk of osteomalacia
Institutionalised
what causes rickets or osteomalacia
Severe nutritional vitamin D or calcium deficiency causes insufficient mineralisation.
Vit D stimulates calcium and phosphate absorption from the gut which then becomes available for bone mineralisation.
So less vit D means less Calcium and phosphate so less bone mineralisation
Apart from reduced bone mineralisation, what else in the body is affected by low vitamin D states
Muscle function
What is osteogenesis imperfecta
Genetic disorder of connective tissue characterised by fragile bones from mild trauma and even acts of daily life
Who does OI affect
Broad range from prenatally fatal to those presenting in 40s with “early osteoporosis
Where is the defect which causes OI
Defects in type I collagen
What are the 4 most common types of OI
T1 - milder form, occurs when child starts to walk, can present in adults
T2 - lethal by age 1
T3 - progressive deforming with severe bone dysplasia and poor growth
T4 - similar to T1 but more severe
Other clinical features of OI (7)
Growth deficiency
Defective tooth formation (dentinogenesis imperfecta)
Hearing loss
Blue sclera
Scoliosis / Barrel chest
Ligamentous laxity (hyper mobility brighten score)
Easy bruising
Management of OI (4)
Surgery to treat fractures
IV Bisphosphonates (to prevent fracture)
Educational and social adaptations
Genetic counselling for parents and next generation
What is osteoporosis
A metabolic bone disease characterised by low bone mass and deterioration of bone tissue resulting in bone fragility and increased fracture risk
What tools are used to assess fracture risks (2) - what do they assess and what are the difference between these tools
Both assess 10 year probability of bone fracture risk
FRAX - uses clinical risk factors and BMD at the femoral neck
Q Fracture - does not have ability to add BMD
If a patient has significant risk of fracture result from FRAX/Q Fracture, what should they be referred for
DEXA scan
risk >10%
Who should be referred for a DEXA scan for osteoporosis regardless of their fracture risk percentage
If on oral steroids
If suffered a low trauma fracture
What does DEXA scan measure
Bone mineral density which is then compared to the BMD of a healthy adult and someone who is same age and sex as patient.
The difference is calculated as a SD and called a T score
What T score is defined as osteoporosis
Below -2.5 SD
What bones are good to scan in DEXA and why
L1-L4 as spine has more cortical bone than trabecular bone so commonly affected by osteoporosis
L1-4 also doesn’t have other bones around it to interfere with the scan
Endocrine causes of osteoporosis (6)
Thyrotoxicosis Hyper and Hypoparathyroidism Cushing's Hyperprolactinaemia Hypopituitarism Low sex hormone levels
Rheumatic causes of osteoporosis (3)
RA
Ankylosing Spondylitis
Polymyalgia Rheumatica (steroids used making bones thin)
GI causes of osteoporosis (11)
IBD Primary biliary cirrhosis Alcoholic cirrhosis Congenital adrenal hyperplasia Viral cirrhosis (hep C) Cystic Fibrosis (causes malabsorption) Chronic pancreatitis Coeliac disease Whipple's disease Short gut syndromes Ischaemic bowel
Medications which cause osteoporosis
Steroids PPI Enzyme inducing anti-epileptic medications Aromatase inhibitors GnRH agonists Warfarin
Non pharmacological ways to prevent osteoporosis
Minimise risk factors
Ensure good calcium and Vitamin D status
Falls prevention strategies
Medications to treat osteoporosis (5)
Oral bisphosphonates (main)
HRT
Selective Oestrogen Receptor Modulator-Raloxifene (SERMS)
Denosumab s/c injection (6m)
Teriparatide (human parathyroid hormone) injection
What needs to be checked for bisphosphonates
Renal function
Calcium and Vit D status
Good dental health and hygiene - notify dentist
Side effects of bisphosphonates (4)
Osteonecrosis of Jaw
Oesophagitis
Iritis / uveitis
Atypical femoral shaft fractures
Side effects of HRT
Blood clots risk
Breast cancer risk increased
Heart disease and stroke risk increased if used after large gap from menopause
Side effects of SERMS
Hot flushes
Increased clotting risks
Leg cramps
What is denosumab and how does it help in osteoporosis
Monoclonal antibody against RANKL
Reduces osteoclastic bone resorption
Safer in patients with significant renal impairment
Side effects of denosumab
Allergy / rash
Symptomatic hypocalcaemia if given when via D depleted
ONJ
Atypical femoral shaft #
Teriparatide side effects
injection site irritation
Hypercalcaemia (rare)
allergy
COST
