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BDS3 BAMS > Bone disease > Flashcards

Bone disease Flashcards

1
Q

What does Arthritis mean?

A
  • Inflammation of joints
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2
Q

What does Arthrosis mean?

A
  • Non inflammatory joint disease
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3
Q

What does Arthralgia mean?

A
  • Joint pain
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4
Q

What is bone?

A
  • Mineralised connective tissue
  • It is load bearing
  • It is dynamic (continuously changing)
  • It is self repairing
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5
Q

What is the bone turnover cycle?

A
  • Bone removed by osteoclasts
  • Bone Deposited by osteoblasts
  • Osteoclasts eat away at bone matrix
  • Replaced by osteoblasts that deposit osteoid matrix
  • Matrix undergoes collagen formation/mineralisation
  • Bone formation takes 3-6months
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6
Q

What is required in bone turnover cycle?

A
  • Correct amounts of
  • Calcium
  • Phosphate
  • Vitamin D
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7
Q

Why is bone turnover necessary?

A
  • In order to maintain calcium homeostasis to replace hypermineralised foci with younger tougher tissue
  • Restore bone that has become defective through development and propagation of microfractures
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8
Q

How are Bone and Calcium linked?

A
  • Bone forms a store for calcium
  • Some is exchangeable and some isn’t
  • Exchangeable calcium moves from bone to extracellular fluid and calcium absorbed from gut through ECF
  • Calcium lost through gut and urine
  • Bone and ECF work together and parathyroid hormone used to ensure correct level of calcium maintained
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9
Q

Why is it important calcium is maintained at precise level in blood?

A
  • Normal body function
  • Involved in nerve and muscle function
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10
Q

How does low dietary calcium affect the body?

A
  • Reduction in plasma calcium
  • Increased Parathyroid hormone secretion
    1. Increases active vitamin D which increases intestinal calcium absorption
    2. Decreases urinary calcium which increases conservation of dietary calcium
    3. Increases bone loss which increase bone calcium release
  • All lead to restoration of normal plasma calcium levels
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11
Q

What does the parathyroid hormone do?

A
  • Found in parathyroid glands
  • Maintains serum calcium level
  • Raises if calcium levels fall
  • Increases calcium release from bone
  • Decreases renal calcium excretion
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12
Q

What is hypoparathyroidism?

A
  • Low conc of parathyroid hormone
  • Results in low serum calcium
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13
Q

What is hyperparathyroidism?

A

Primary
- Due to gland dysfunction like a tumour
- Results in high serum calcium
- Inappropriate activation of osteoclasts

Secondary
- Occur when low serum calcium
- Increase activation of osteoclasts to maintain appropriate calcium level

  • Both result in increased bone reabsorption (resorption)
  • See radiolucency in radiographs on bone where reabsorption occurs
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14
Q

How is Vitamin D absorbed by body?

A
  • Can be absorbed from UV ray from sun or from 7-dehydrocholestrol in diet
  • Get absorbed as Cholecalciferol in skin
  • Becomes bound Cholecalciferol in blood
  • Becomes 25-hydroxycholecalciferol in liver
  • Becomes 1,25-dihydroxyxolecalciferol in kidneys which is the active component necessary for calcium absorption in the GIT
  • Calcium needed for muscle and bone health
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15
Q

What foods can you get Vitamin D from?

A
  • Orange juice
  • Fish
  • Milk
  • Supplements
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16
Q

What are some vitamin D problems?

A

Low sunlight exposure can be problem
- Housebound
- Dark skinned in Northern country as they absorb sunlight less efficiently
- Diet is more relied upon

Poor GI absorption
- Due to poor nutrition
- Small intestinal disease can lead to malabsorption

Drug interactions
- Some antiepileptic drugs like carbamazepine, Phenytoin can interfere with vit D synthesis

Vit D deficiency is usually a combo of factors

17
Q

What is Osteomalacia?

A
  • Softening of bones typically through vit D or calcium deficiency
  • Normal bone matrix formed but not calcified properly
  • Poorly mineralised osteoid matrix
  • Poorly mineralised cartilage growth plate
  • Normal amount of osteoid but not enough mineralisation so softening occurs
18
Q

What is Osteoporosis?

A
  • Reduced quantity of normally mineralised bone
  • Age related change and is inevitable
  • Weakens bones so very easily breakable
19
Q

What disease occurs when Osteomalacia occurs during bone formation?

A
  • Rickets develops then turns into osteomalacia when bone formation completed
  • Calcium deficiency
  • Serum calcium is preserved in expense of bone mineralisation
  • When calcium in short supply during bone formation can lead to soft bone developing that can bend under pressure
20
Q

What are the effects on bone of Osteomalacia?

A
  • Bones bend under pressure and can be seen as ‘bow legs’ in children
  • Vertebral compression is seen in adults and cause bone aching to touch
21
Q

What are the Hypocalcaemia effects of Osteomalacia?

A
  • Muscle weakness
  • Show signs of Trousseau and Chvostek leading to carpal muscle spasm and facial twitching from CN VII tapping
22
Q

What is Alkaline Phosphatase a measure of?

A
  • Measure of bone turnover
  • Very high when issues with calcium levels
23
Q

What levels in blood are we expecting with Osteomalacia investigations?

A
  • Serum Calcium decreased
  • Serum Phosphate Decreased
  • Alkaline Phosphatase Very high
  • Plasma creatine increased due to renal cause
  • Plasma Parathyroid hormone increased due to secondary hyperparathyroidism
24
Q

How is Osteomalacia managed?

A

Firstly correct the cause

If malnutrition - Control GI disease and get more vit D in diet via supplement
If sunlight exposure - 30mins X 5weekly

25
Q

What are the risk factors for Osteoporosis?

A
  • Age
  • Female higher risk

Endocrine
- Oestrogen and testosterone deficiency increase risk
- Cushings syndrome (increase corticosteroid levels in blood- higher risk)

Genetic
- Family history
- Race (caucasian and asian women)
- Early menopause

Patient factors
- Inactivity
- Smoking
- Excess alcohol use
- Poor dietary calcium

Medical Drug use
- Steroids
- Antiepileptics

26
Q

Why do women have higher risk of developing Osteoporosis?

A
  • Males have higher Peak bone mass
  • Oestrogen withdrawal (during menopause) increases bone mass loss rate in women
  • Takes longer for men to loss enough bone mass to get to osteoporosis
  • Expected peak bone mass of men and women a lot closer than 100years ago due to exercise and women being a lot more active
27
Q

What are the effects of Osteoporosis?

A

Increased bone fracture risk
- Applies to long bones
- Usually first clinical sign is when a patient falls and breaks their wrist easily

Vertebrae can also be affected
- Height loss
- Kyphosis (curvature of spine causing top of back to appear more rounded)
- Scoliosis (Curvature of spine laterally)
- Nerve root can be compressed leading to back pain

28
Q

How can Osteoporosis be prevented?

A
  1. Build maximal Peak bone mass
    - Through exercise and high dietary calcium intake
    - For young adults
    - Gain as much bone mass as poss so effects of osteoporosis take longer to occur
  2. Reduce rate of Bone mass loss
    - Continue exercise and calcium intake
    - Reduce hormone related effects
    - Not clear if Oestrogen hormone replacement therapy is continually beneficial but most effective if early menopause
  3. Reduce drug related effects
    - Useful when patients have family history
    - Consider Osteoporosis prevention drugs (bisphosphonates)
29
Q

What is Hormone Replacement Therapy?

A

Oestrogen only HRT
- Reduces osteoporosis risk
- Increases breast cancer risk
- Increase endometrial cancer risk (patients who haven’t had hysterectomy combine with progestogen to reduce risk)
- May reduce ovarian cancer risk
- Increase DVT risk (Deep vein thrombosis)
- Benefit is lost after HRT stops
- Bone marrow density returns to normal 5years after HRT stops

30
Q

What are the two types of Bisphonates?

A

Non-nitrogenous e.g. Etidronate

Nitrogenous e.g. Ibandronate, Zoledronate (extremely potent)

dronate

31
Q

How do Bisphononates work?

A
  • Act by preventing osteoclast working by poisoning osteoclast and reduces number
  • Reduces osteoclasts then less bone mass removed and preserving bone mass present
32
Q

How effective are Bisphosphonates?

A
  • Extremely effective
  • Reduce vertebral fracture risk by 50%
  • Reduce other fractures by 30-50%
  • Benefit is lost if drug discontinued
  • Can be combined with HRT

BDS3 BAMS (15 decks)

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