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Flashcards in Metabolic Bone Disease Deck (42):

What causes Rickets and Osteomalacia?

What is the difference between the two?

Severe nutritional vitamin D deficiency causes insufficient mineralisation and thus rickets in a growing child and osteomalacia in the adult when the epiphyseal lines are closed


What are the signs of osteomalacia?

Soft spot on baby's head is slow to close

"Bony necklace" of nodules around ribs

Curved bones

Big, lumpy joints

Bowed legs


What is Paget's disease?

What goes wrong and what does it lead to?

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 deformity and fracture


What are the symptoms of Paget's disease?

When does it present?

Presents in a patient >40 years with bone pain

Occasionally presents with bone deformity, excessive heat over the pagetic bone or by neurological complications (deafness)


Paget's disease effecting the skull can lead to what?



What is the genetic component of the aetiology of Paget's disease?

How does this play into geographic distribution?

Strong genetic component
15-30% are familial

Restricted geographic distribution: those of Anglo-Saxon origins


Possibility of chronic viral infection within osteoclasts may lead to what?

Paget's disease


What blood test will be elevated in the majority of Paget's disease?

Alk Phos

May be an isolated elevation that is picked up by chance (should be looked into)


What may Paget's present with on very rare occasions?

(what very rare complication occurs in Paget's)

Osteosarcoma of affected bone


What is osteogenesis imperfecta?

(broad definition)

Genetic disorder of connective tissue characterised by fragile bones from mild trauma and even acts of daily life


How does osteogenesis imperfecta vary?

Why is this?

Broad clinical range due to 8 different defects in type 1 collagen


What are the 4 most common defects in type 1 collagen that occur in osteogenesis imperfecta?

Type 1:
-Milder form
-When child starts to walk and can present in adults

Type 2:
-Lethal by age 1

Type 3:
-Progressive deforming with severe bone dysplasia and poor growth

Type 4:
-Similar to type 1 but more severe


What are the signs of osteogenesis imperfecta?

Growth deficiency

Defective tooth formation
(dentigenesis imperfecta)

Hearing loss

Blue sclera


Barrel chest

Ligamentous laxity

Easy bruising


How do you treat osteogenesis imperfecta?

Pins put in place in childhood

These support bone and grow with the bone as the child grows


What is the definition of osteoporosis?

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 result on a DXA bone scan would define osteoporosis?


What is a low trauma fracture?

A fracture due to a force equivalent to a fall from standing height or less

You shouldnt break a bone when you fall over. Something is wrong with the bone if you do


What are the 3 classic fractures in osteoporosis?

Wrist, spine and hip


What low trauma fractures do not suggest osteoporosis?

(when seen these wouldnt make you worry about osteoporosis)?

Nose and Skull


What 6 things make people at risk of having thin bones?


Genetic predisposition

Nutritional factors
-Low body weight and poor calcium and Vit D intakes


Diseases which influence bone turnover:
-Inflammatory arthritis

-Aromatase inhibitors
-Diabetic medications


How does bone mass change as we age?

As we grow bone mass increases

At around 20 we stop growing and reach peak bone mass at 30

Accelerated loss begins at menopause

Gradual loss in elderly

(this is all effected by the level of activity of osteoclasts and osteoblasts)


What 4 factors effect peak bone mass?

Genetic factors

Nutritional factors

Exercise (weights)

Influenced by disease processes and by drugs such as corticosteroids


What 5 factors effect age related bone loss?

Loss of sex hormones

Genetic factors

Nutritional factors

Exercise (weights)

Drugs such as corticosteroids and aromatase inhibitors


How do you measure bone mass?

DEXA scan

-Calculate bone mass along with T and Z score


What is T score and Z score?

T score:
-Compares bone mass to that of a younger person
-Same ethnicity and sex

Z score:
-Compares bone mass to peers
-Same age, ethnicity and sex


How do you use T-score to decide when to treat?

(Give score and treatment)

Normal (T score above -1)
-Lifestyle advice

Osteopenia (T score between -1 and -2.5)
-Lifestyle advice
-Treat if previous fracture

Osteoporosis (T score less than -2.5)
-Lifestyle advice
-Offer treatment


What is referral for DEXA scan dependent on?

(how do clinicians decide when to do a DEXA scan?)

Based on FRAX or QFracture score >10% fracture risk at any site over next 10 years


Name some independent risk factors for osteoporosis used in FRAX score

Prior fracture

Family history of fracture

Current smoking

Ever use of corticosteroids

Alcohol (3 or more units a day)

Rhaumatoid arthritis


What are some of the limitations of the FRAX score?

Not all known risk factors included:
-Falls, biochemical markers

Lacls detail on some risk factors:
-Dose of corticosteroids, smoking, prior fracture

Depends on adequacy of epidemiological information

Limited country models available

Model relevant only for untreated patients

Does not replace clinical judgment


What length of steroid use puts someone at risk of steroid induced osteoporosis?

3 or more months


What are the side effects of HRT treatment in osteoporosis?

Increased risk of clotting

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


What does SERM stand for?

Selective oEstrogen Receptor Modulator

Form of HRT used in osteoporosis which reduces the rates of vertebral fracture

(NO effect on non-vertebral fracture rates)


What are the side effects of SERMs?

Hot flushes if taken close to menopause

Increased clotting risks

Lack of protection at hip site


What are the main treatments for osteoporosis?

What do they do?


Potent anti-resorptive agents


Name 3 bisphosphonates



What are the side effects of bisphosphonates?


Iritis/ uveitis

Osteonecrosis of the jaw (ONJ)

Atypical femoral shaft fractures


What is the mechanism of action of strontium ranelate in osteoporosis?

Strontium replaces calcium in bone


What are the side effects of strontium ranelate?

Increased clotting risks

Increased cardiovascular risks

Artificially elevates bone density and can cause misleading results on future DXA scans


What is teriparatide?

Intermittent Human Parathyroid hormone

Reduces fracture rates.
Really is a brilliant drug


What are the problems with teriparatide?

(side effects etc)

Injection site irritation

Rarely hypercalcaemia




What is Denosumab?

(what does it do? how is it given? what is the advantage?)

Monoclonal antibody against RANKL

Reduces osteoclastic bone resorption

Subcutaneous injection every 6 months

Safer in patients with significant renal impairment than bisphosphonates


What are the side effects of denosumab?

Allergy/ rash

Symptomatic hypocalcaemia if given when Vit D deplete
-Ca2+ can drop rapidly risking arrythmia

Atypical femoral shaft fractures