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Ageing block > Osteoporosis & metabolic bone disease > Flashcards

Osteoporosis & metabolic bone disease Flashcards

1
Q

What is bone and what are it’s functions

A

-Bone is a living tissue
Functions:
-Mechanical=supports muscle attachment
-Protective=to vital organs and bone marrow
-Metabolic-reserve for calcium& phosphate ions

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2
Q

State the different types of bone

A
  • Flat
  • Long
  • Sesamoid
  • Cortical
  • Trabecular
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3
Q

What is remodelling/turnover

A

-A lifelong process where mature bone tissue is removed from the skeleton (a process called bone RESORPTION) and new bone tissue is formed (a process called OSSIFICATION or new bone formation)

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4
Q

What influences turnover

A
  • Age
  • peak bone mass
  • Hormones
  • Nutrition
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5
Q

State the characteristics of cortical bone

A
  • 85% of skeleton mass
  • Abundant in shaft of long bones
  • Largely affected by hyperparathyroidism and post-menopausal period
  • Controlled by systemic hormones and parathyroid hormones(PTH)
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6
Q

State the characteristics of trabecular bone

A
  • 15% of skeleton mass
  • Has a larger SA
  • Bone remodelling occurs in environment of narrow cells & cytokines
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7
Q

Explain how bone turnover occurs

A
  • OsteoCLASTS= large nucleated cells responsible for bone resorption
  • Under the influence of signals the osteoclasts (receptor activator of nuclear factor kappa B-ligand ((RANKL)), interleukins, PTH,cytokines etc) initiate bone resorption)
  • An acidified micro-environment is created between the osteoclasts and cell surface causing mobilization of mineralized content
  • After osteoclastic resorption and apoptosis, proliferation of osteoblasts occur and finally mineralized bone is formed
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8
Q

How can we classify markers of bone turnover

A
  1. ) Bone resorption markers

2. )Bone formation markers

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9
Q

State the bone resorption markers

A 
Urine:
-Hydroxyproline
-C telopeptide of type I collagen 
-N telopeptide of type I collagen
Serum:
-NTX
-CTX
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10
Q

State the bone formation markers

A

Serum:

  • Bone specific alkaline phosphatase
  • Osteocalcin
  • P1CP
  • P1NP
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11
Q

Around what age bracket does the peak bone mass occur

A

25-40

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12
Q

When does bone mass start to decline

A

For females=menopause

For males & females= after 40

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13
Q

What is DEXA

A
  • Dual energy X-ray absorptiometry
  • A bone density scan using densitometry X-ray measures how much mineral is in the area being measured
  • Results are given as ‘standard deviation’ (the number of units above or below average)
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14
Q

Define osteoporosis

A
  • Systemic skeletal disorder
  • Low bone mass
  • Microarchitectural deterioration of bone tissue
  • Increased risk of fracture
  • A bone mineral densitry (BMD) Below 2.5 SD
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15
Q

Define osteopenia

A
  • A bone density between lower end of normal range and osteoporosis
  • A value of BMD between 1 and -2.5 SD
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16
Q

Define fragility fracture

A

A fracture following a fall from standing height or less, although vertebral fractures may occur spontaneously or as a result of routine activities

17
Q

Why are woman at greater risk of osteoporosis?

A

-Due to the decrease in oestrogen production at the menopause, which accelerates bone loss

18
Q

Outline the modifiable determinants of low bone structure and function

A
  • Smoking
  • Alcohol intake> 14units/week
  • Low BMI<18.5 kg/m2
  • Current or frequent use of glucocorticoid
  • Vit D& calcium homeostasis
19
Q

Outline the non-modifiable determinants of low bone structure and function

A
  • Age: bone density decreases as you get older
  • Gender: women accumulate less peak bone mass and lose more following menopause
  • Ethnicity: caucasians & asians are at higher risk
  • Previous fragility
  • Family history of hip fracture
20
Q

How is diabetes associated with low bone mass

A
  • women with T1DM are 12x more likely to get hip fracture
  • Women with T2DM have a 1.7 fold risk of hip fracture
  • Low bone turnover, reduced anabolic effect of insulin and IGF1
  • Poor vision,neuropathy increase potential of fracture
21
Q

Which diseases are associated with low bone mass

A
  • Diabetes
  • Inflammatory rheumatic disease
  • GI diseases
  • Chronic liver disease
  • Chronic kidney disease
  • CF
  • HIV
  • Epilepsy
  • MS
  • Stroke
22
Q

How can we quantify fracture risk?

A
  • FRAX calculated 10year absolute risk of major osteoporotic fracture & hip fracture
  • Hip BMD predicts fracture risk more than spine
  • Bone markers in urine and serum are useful to monitor treatment and not for diagnosis
23
Q

What investigations are useful for osteoporosis and metabolic bone disease?

A
  • Bone profile: corrected calcium, phosphate, alkaline phosphatase, magnesium
  • PTH
  • 25 OH vitamin D
  • Renal functions & LFTs
  • Serum electrophoresis
  • Coeliac screen
  • TFTs
  • Gonadotrophins
  • DEXA
  • x-rays
  • MRI
24
Q

How can we manage osteoporosis ?

A
  1. ) exercise interventions:
    - static and dynamic weight bearing exercises slows down decline of hip and lumbar BMD
  2. ) Diet:
    - adequate calcium in diet to meet the recommendations of 700-1000 mg/day
    - Because of inadequate sunshine hours and diet low in vit D at least 800 IU of vitamin D3 is recommended
25
Q

How do we treat vitamin D deficiency?

A

Oral vitamin D3/cholecalciferol

26
Q

What is the function of vitamin D?

A
  • essential for musculoskeletal health

- Promotes calcium absorption of newly formed osteoid tissue in bone and plays an important role in muscle function

27
Q

Outline the guidelines for serum 25OHD (Vitamine D)

A
  • Serum 25OHD< 30nmol/L=deficient
  • Serum 25OHD of 30-50nmol/L is inadequate
  • Serum 25OHD>50nmol/L is sufficient for almost the whole pop.
28
Q

Outline the pharmacological treatment available for osteoporosis/ metabolic bone disease

A
  1. )Bisphosphates (this is the bone sparing therapy)prevent vertebral, non-vertebral and hip fractures in men& women
    - available as weekly, monthly tablets & yearly infusions
    - treat for a period of 3-5years unless on steroids, >75years of has a previous fracture
    - Long term risk of osteonecrosis of the jaw and atypical fracture
  2. ) HRT in younger post-menopausal women
    - Selective oestrogen receptor modulators (SERMs)
    - Testosterone replacement in some hypogonadal men
    - Denosumab
    - Teriparatide
29
Q

What does BMD stand for (disease)

A

Becker muscular dystrophy

30
Q

Why do we limit the period of time we treat a osteoporosis pt with bisphosphates?

A
  • Bisphosphates generally keep bone turnover low

- So if we don’t limit the time we may end up with a bone that is excessively mineralised but unable to protect itself

31
Q

Outline Paget’s disease of the bone

A
  • Localised disorder of bone remodelling
  • Disorganised mosaic of new bone formation resulting in less compact, more vascular and bone susceptible to deformity & fracture
  • Driven by genetic and environmental factors
  • Can affect 1.5 to 8% of the population, more common in europeans
  • Rare in people younger than 55
  • More common in men (3:2)
  • Presents with bone pain,deformities, fractures or isolated increase in BALP
  • Bisphosphates are the mainstay of treatment
32
Q

Outline the different enzyme disorders

A
  1. )Hypophosphatasia
  2. )Mucopolysacccharidosis
  3. )Homocysteinurea
  4. )Alkaptonuria
33
Q

What is hypophosphatasia

A
  • heritable rickets
  • sub-normal BALP activity
  • depending on severity can present in infantile,childhood or adults
34
Q

What is Mucopolysacccharidosis?

A
  • diminished activity of lysosomal enzymes that degrade glycosaminoglycans
  • accumulation of complex CHO within the bone marrow
35
Q

What is homocysteinurea?

A
  • Autosomal recessive disorder
  • cystathione Beta deficiency
  • Marfanoid habitus
  • Thromboembolism
  • osteoporosis
36
Q

What is alkaptonuria?

A
  • Autosomal recessive disorder
  • Homogentisic acid oxidase deficiency
  • Accumulation homogentisic acid
  • discolouration of urine and CT
37
Q

Outline the affect cancer has on bone

A
  • Bone metastasis occurs in 80% of pts with advanced breast or prostate calcium & 15-30% of thyroid, lung or renal calcium
  • Metastatic cancer cells flourish within the bone microenvironment
  • Present as severe pain, pathological fractures or abnormalities in calcium
  • Accelerated bone loss occurs following therapy for breast and prostate calcium
  • Steroids and/or immunomodulant used for treatment during BMT(bone marrow transplantation) result in bone loss

Ageing block (16 decks)

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