Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MSK > Metabolic Bone Disease > Flashcards

Metabolic Bone Disease Flashcards

1
Q

Pre-osteoclasts are formed from what type of progenitor cell?

A

Myeloid progenitor cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Pre-osteoblasts are formed from what type of progenitor cell?

A

Mesenchymal progenitor cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Many Factors Stimulate Osteoblast Expression of RANK Ligand, name 3.

A
  • Osteoblasts appear to be controlling cell of bone turnover
  • Vitamin D
  • Glucocorticoids
  • IL-1, IL-11
  • RANK ligand required for activated osteoclast
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where does vitamin D come from?

A
  • Sunshine

* Diet - oily fish, egg yolk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What reaction occurs when UV rays hit the skin?

A

7DHC (hydrocholesterol) is transformed into a precursor of Vit D which circulates protein bound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What stage of Vit D pathway occurs at the liver?

A

Conversion of the Vit D precursor to 25(OH)vit D - MAIN STORAGE FORM OF VITAMIN D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What stage of Vit D pathway occurs at the kidney?

A

Conversion of 25(OH)vit D to 1,25(OH)2 vit D - ACTIVE FORM OF VITAMIN D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the main function of vit D?

A

•Absorption of calcium from the gut

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is another role of vit D?

A

•Works with parathyroid to move calcium in and out of tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What test is used to measure vit D status?

A

25-hydroxy vit D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What can caused vit D deficiency?

A
  • Kidney and liver disease
  • Darker skin - melanocytes competing for the UV radiation and prevent first reaction
  • Older people have less 7DHC in skin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why is regulation of calcium metabolism so important?

A

To maintain Ca2+ levels in the ECF (at expense of bon calcium)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does parathyroid hormone do?

A

Regulates calcium levels (stimulates active vit d production etc.)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is Paget’s disease?

A
  • LOCALISED disorder of bone turnover

* Increased bone resorption followed by increased bone formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the bone features of Paget’s?

A
  • Disorganised bone
  • Bigger
  • Less compact
  • More vascular
  • More susceptible to deformity and fracture
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the aetiology of Paget’s?

A
  • Relatively common
  • Strong genetic component - 15-30% are familial
  • Loci of SQSTMI
  • Restricted geographic distribution - those of Anglo-Saxon origins
  • Environmental trigger - possibility of chronic viral infection within Osteoclast (in youth)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the symptoms of Paget’s?

A
  • > 40s
  • Bone pain
  • Occasionally presents with bone deformity
  • excessive heat over affected (Pagetic) bone
  • Neurological complications such as deafness
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the clinical signs of Paget’s?

A
  • Isolated elevation of serum alkaline phosphatase - do not treat on this alone (incidental finding)
  • Occasionally the development of osteosarcoma in the affected bone
  • Do x-ray then isotope bone scan (for metabolic activity)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the treatment of Paget’s?

A
  • No evidence to treat if asymptomatic unless in skull or an areas requiring surgical intervention
  • Intravenous bisphosphonate therapy - one-off zoledronic acid infusion, oral option is also available

ZOLEDRONIC ACID

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are rickets and osteomalacia?

A
  • Severe nutritional vit D or calcium deficiency causing insufficient mineralisation
  • 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
  • Rickets - in growing child
  • Osteomalacia - in adult when the epiphyseal lines are closed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How does rickets present?

A
  • Stunted growth
  • Large forehead
  • Odd-shaped legs
  • Odd-shaped ribs and breast bones
  • Wide joint at elbow, wrist and ankle
  • Odd curve to spine or back
  • Wide bones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How does osteomalacia present?

A
  • Particularly in elderly - housebound/institutionalised
  • Bone pain
  • Muscle weakness
  • Increased falls risk
  • More common in POC
  • May see micro-fractures on x-rays
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How are rickets and osteomalacia treated?

A

•Vit D and calcium supplementation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is osteogenesis imperfecta?

A
  • Genetic disorder of connective tissue characterised by fragile bones from mild trauma and even acts of daily life
  • Defect in type 1 collagen
25
Q

Which of the 28 types of type 1 collagen defect are most common?

A

1-4

26
Q

How is type 1 characterised?

A

Milder form-when child starts to walk and can present in adults

27
Q

How is type 2 characterised?

A

Lethal by age 1

28
Q

How is type 3 characterised?

A

Progressive deforming with severe bone dysplasia and poor growth

29
Q

How is type 4 characterised?

A

Similar to type 1 but more severe

30
Q

What are other clinical features of osteogenesis imperfecta?

A
  • Growth deficiency
  • Defective tooth formation (dentigenesis imperfecta)
  • Hearing loss
  • BLUE SCLERA
  • Scoliosis/Barrel Chest
  • Ligamentous laxity - HYPERMOBILTIY (Beighton score)
  • Easy bruising
31
Q

How if OI treated?

A
  • Surgical - treat fractures
  • Medical - IV bisphophonates (to prevent fracture)
  • Social - educational and social adaptations
  • Genetic - genetic counselling for parent and next generation
32
Q

What is osteoporosis?

A
  • 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
33
Q

What are risk factors for fractures in osteoporosis?

A
  • Age
  • BMD - bone mineral density
  • Falls
  • Bone turnover
34
Q

What is FRAX?

A

WHO fracture risk assessment tool

35
Q

Q fracture is another risk assessment tool for fracture risk which was developed in the UK. What variables does it take into account?

A
  • CV risk
  • Falls
  • TCA (tricyclic antidepressants)
  • Does not have the ability to add BMD
36
Q

When should a patient be referred for a DXA scan?

A
  • When risk assessment score is greater than 10%
  • When they are on oral steroids
  • When they have had a previous scan
37
Q

What does a DXA scan measure?

A
  • BMD
  • T-score - compares patient to young adult (only age is not the same)
  • Z-score - compares patient to absolute peer group
38
Q

Who is at risk of osteoporosis?

A
  • I in 2 women over 50 will have an osteoporotic fracture before they die
  • I in 5 men over 50 will suffer and osteoporotic fracture
  • A 50 year old woman has a lifetime risk of 17% of a hip fracture
  • If you suffer 1 vertebral fracture you are 5 times more likely to have another and twice as likely to have hip fracture than if you had no vertebral fractures
39
Q

What are the endocrine causes of osteoporosis (7)?

A
  • Thyrotoxicosis - hyperthyroidism
  • Hyper and Hypoparathyroidim
  • Cushings (hypercortisolism)
  • Hyperprolactinaemia
  • Hypopituitarism
  • Low sex hormone levels
40
Q

What are the rheumatic causes of osteoporosis (3)?

A
  • Rheumatoid arthritis
  • Ankylosing Spondylitis
  • Polymyalgia Rheumatica
41
Q

What are the gastroenterological causes of osteoporosis (3)?

A
  • Inflammatory diseases - UC and crohns
  • Liver diseases - PBC, CAH, Alcoholic cirrhosis, Viral cirrhosis (Hep C)
  • Malabsorption - Cystic Fibrosis, chronic pancreatitis, coeliac disease, whipples disease, short gut syndromes and ischaemic bowel
42
Q

Which medications cause osteoporosis?

A
  • Steroids
  • PPI
  • Enzyme inducting antiepileptic medications
  • Aromatase inhibitors - post-menopausal women
  • GnRH inhibitors
  • Warfarin
43
Q

How does our bone mass change with time?

A
  • Increases to ~30y
  • Decreases >40y
  • Accelerated loss after menopause
44
Q

How do we prevent osteoporotic fractures?

A
  • Minimise risk factors
  • Ensure good calcium and Vitamin D status
  • Falls prevention strategies
  • Medications - HRT
45
Q

What are the side effects of HRT?

A
  • 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, would not start if 2-3 years have passed
  • Increased risk of prostate cancer in men
  • No HRT after 60 years
46
Q

What are SERMs?

A
  • Selective oEstrogen Receptor Modulators
  • Raloxifene - reduce vertebral fracture rate but no effect on other bones
  • Reduce breast cancer risk

RALOXIFENE

47
Q

Negative effects of SERMs?

A
  • Hot flushes if taken close to menopause
  • Increased clotting risks
  • Lack of protection at hip site
48
Q

What is the main osteoporosis treatment?

A
  • Bisphosphonates
  • Oral Bisphosphonates generally the first line of treatment
  • Adequate Renal function required
  • Adequate Calcium and Vitamin D status
  • Good Dental Health and Hygiene advised - Notify dentist on Bisphosphonates, Encourage regular check ups/well fitting dentures
49
Q

How do bisphophonates work?

A
  • Bisphosphonate binds to bone mineral
  • When the osteoclast breaks down the bone, it takes the bisphosphonate too
  • The bisphosphonate poisons the osteoclast
  • The osteoclast becomes aware it is damaged at carries out apoptosis
  • The bisphophonate and the bone it was secured to are both regurgitated by the osteoclast back onto the bone surface
50
Q

What are the side effects of bisphosphonates?

A
  • Oesophagitis
  • Iritis/uveitis
  • Not safe when eGFR<30 mls/min

Extremely rare:
•ONJ - osteonecrosis of the jaw
•Atypical femoral shaft fractures

51
Q

When is a drug holiday taken from bisphosphonates?

A
  • Drug Holiday for 1-2 years
  • Usually after 10 years Oral Bisphosphonates
  • 5 year course very safe
52
Q

What is denosumab?

A
  • Monoclonal antibody against RANKL
  • Prevents any osteoclastic stimulation
  • Reduces osteoclastic bone resorption
53
Q

How is denosumab administered?

A
  • Subcutaneous injection every 6 months

* Allows bone to break down

54
Q

Why is denosumab beneficial?

A
  • Safer in patients with significant renal impairment then bisphosphonates
  • Reduce risk of hip fracture
  • Use in older individual
55
Q

What are the side effects of denosumab?

A
  • Allergy/rash
  • Symptomatic hypocalcaemia if given when vitamin D depleted
  • Rebound fracture risk when treatment stopped
  • ?ONJ
  • ? Atypical femoral shaft fractures
56
Q

What is teriparatide?

A
  • Intermittent human parathyroid hormone (IHPT)

* Used in people having vertebral fractures despite other therapies

57
Q

How is teriparatide administered?

A

•Daily injection

58
Q

What are the side effects of teriparatide?

A 
•Injection site irritation
•Rarely hypercalcaemia
•Allergy
•Limited to one course due to osteosarcoma risk - seen in rats
COST

MSK (28 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions