Metabolic Bone Disease Flashcards by Ellen Stewart

What is Paget’s disease

Disorder of bone turnover

There is increased bone resorption followed by increased bone formation leading to disorganised bone

How well did you know this?

Not at all

Perfectly

What is bone like in Paget’s (4)

Bigger
Less compact
More vascular
More susceptible to deformity and fracture

How well did you know this?

Not at all

Perfectly

What percentage of Paget’ is familial - what is the gene involved

15-30%
Loci of SQSTMI
Anglo-Saxon origins

How well did you know this?

Not at all

Perfectly

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)

How well did you know this?

Not at all

Perfectly

What age group does Paget’s occur in

Over 40s

How well did you know this?

Not at all

Perfectly

What scan is used for Paget’s - what does it show

Isotope bone scan shows area of dense bone

How well did you know this?

Not at all

Perfectly

What bone and liver enzyme is affected by Paget’s and how

Serum alkaline phosphatase is elevated

How well did you know this?

Not at all

Perfectly

differential of Paget’s

metastatic cancer

How well did you know this?

Not at all

Perfectly

When is treatment for Paget’s indicated

If in skull or area requiring surgical intervention - do not treat based on a raised AlkPhos alone

How well did you know this?

Not at all

Perfectly

What medication is used for Paget’s

IV bisphosphonate

How well did you know this?

Not at all

Perfectly

what is a type of bisphosphonate used for Pagets

Zoledronate injection (one off)

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

Clinical presentation of rickets (4)

Stunted growth
Bandy legs (wide)
Large skull (fontanelles do not fuse)
Failure to thrive

How well did you know this?

Not at all

Perfectly

Clinical presentation of osteomalacia (5)

No visible deformity 
Microfractures 
Bone pain 
Muscle weakness
Increased fall risk

How well did you know this?

Not at all

Perfectly

Who is most at risk of osteomalacia

Institutionalised

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

Apart from reduced bone mineralisation, what else in the body is affected by low vitamin D states

Muscle function

How well did you know this?

Not at all

Perfectly

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