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Semester 1 (YEAR 3) - Lecture Notes > Week 7 - Osteoporosis and Parathyroid > Flashcards

Week 7 - Osteoporosis and Parathyroid Flashcards

1
Q

What is osteoprosis

A

Thinning of the bone (low bone mass) and deterioration in bone archeticture
= more susceptible to fractures esp. hip, spine and wrist

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2
Q

How does osteoprosis occur

A
  1. ↓ osteoblasts activity
  2. ↑ osteoclasts actvity
  3. Low peak bone mass
    • bone mass ↑ until reach approx. 25-30 then it peaks off before beginning to decline from age 40-50
    • drops quicker in women due to menopause (sudden ↓ in oestrogen)

Bone is constantly turned over / remodelled

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3
Q

Whats the difference between osteblasts and osteoclast

A

OsteoBlasts - Build new Bone
Osteoclasts - break down old bone (reabsorbed) causing Calcium to be released into blood

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4
Q

Why is osteoporosis a healthcare concern in the UK

A

It is a growing healthcare problem
- affects 1 in 2 women and 1 in 5 men

AIM: ↓ risk of fracture

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5
Q

What factors can influence bone turnover

A
  1. Hormones
  2. Calcium and Vitamin D
  3. Weight bearing exercise
  4. Smoking
  5. Alcohol
  6. Medicines (esp. corticosteroids)
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6
Q

How does hormones affect bone turnover

inc. Oestrogen, Testosterone, Parathyroid, Calcitonin

A
  1. Oestrogen
    • has protective effect on bone
    • ↓ levels causes the rate of bone remodelling to ↑ and reabsortpion ↑ (more than bone formation)
    • menopausal women
  2. Testosterone
    • has protective effecxt on bone
    • ↓ levels = ↑ osteoporosis risk
  3. Parathyroid hormone (PTH)
    • PTH works on kidneys to conserve calcium
    • stimulates calcitrol
    • PTH stimulates osteoclasts = bone reabsorption / bone breakdowm stimulated = Ca2+ released into blood
  4. Calcitonin
    • works on kidneys to excrete calcium (inihibts calcitrol)
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7
Q

List 6 risk factors for developing osteoporosis

A
  • Smoking
  • Alcohol (if drinking > 14 units a week)
  • Low body weight
  • Increasing age
  • History of fracture / family history of fracture
  • Female
  • Oestrogen deficiency
  • Use corticosteroids
  • Low calcium intake
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8
Q

What lifestyle advice should be given to prevent and treat osteoporosis

A
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9
Q

What is the role of Bisphosphonates in managing Osteoprosis

1st Line Treatment = oral bisphosphonates

A

MUST take on EMPTY STOMACH or else bisphosphonates will bind to calcium in food
- need to swallow with water to prevent GI upset or irritation
Have weekly or daily preparations (have diff. licensing)
Check to see if drug is

Oral:
- need to ensure patient has adequate calcium and vitamin D intake
- Used in all patients (if menopausal HRT can be cosndiered too)

IV:
- only used if can’t tolerate oral or having adherence issues

Side Effects:
- GI upset
- Oesophageal irritation

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10
Q

What is the role of Strontium in managing Osteoprosis

2nd line

A

Used ONLY in POSTMENOPAUSAL women with NO CVD
Take at bedtime 2 hrs after food

  • Has similar structure to calcium
    - ↑ bone production (osteoblasts) + reduces reabsorption
  • Can be used separetly or added to bisphosphonate
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11
Q

What is the role of SERMs (raloxifene) in managing Osteoprosis

2nd line | SERM = selective oestrogen receptor modulator

A

Used ONLY in POSTMENOPAUSAL women with NO contraindications
Used in women unresponsive to bisphosphonates
CAN’T USE HRT alongside

  • 2nd line
  • Selective agonist (builds bone ~ osteoblast) + antagonist (reduce bone reabsorption ~ osteoclast) action on oestrogen receptors
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12
Q

What is the role of denosumab in managing Osteoprosis

3rd line | 2nd line in men

A

In men + post-menopausal women (with CVD / other contraindications)
Given as SC injection 2x a year

  • Is a mAb which binds to receptor causing inhibition
    - inhibtion blocks osteoclast action = stops bone being broken down + reabsorbed
    -
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13
Q

What is the role of HRT in managing Osteoprosis

A

Synthetic PTH - ↑ intestinal absorption of Ca2+, ↑ reabsorption of Ca2+ and phosphates from kidneys
- a SC injection
- very expensive
- specialist use ONLY - have to refer to NICE guidelines

HRT - used to treat post-menopausal symtoms

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14
Q

What hormone is secreted from parathyroid gland + what is its role
(note: when have low levels of Ca2+)

A

PTH (parathyroid hormone)

-↑calcium + phosphate re-absorption in kidneys
-↑calcium absorption from intestines
- stimulates osteoclasts (bone reabsorption = Ca2+ is released)

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15
Q

What hormone is secreted from thyroid gland
(note: when have high Ca2+ levels)

A

Calcitonin

-↓ re-absorption of calcium + phosphates in kidney
-↓absorption of calcium in intestines / gut
- inhibits osteoclast activity
Has affects on kidney, gut and bones

NOTE: Calcitrol↑intestinal absorption of calcium

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16
Q

What is Calcitrol and its role

A

It is a hormone AND active form of vitamin D

  • affects how much calcium is absorbed in gut
  • vitamin D from food / produced from sunlight needs to be hydroxylated in both the liver and kidneys
    - if have severe renal or hepatic impairment can become vitamin D deficient (no hydroxylation would occur)
    - causes imbalance in calcium homeostasis = osteoporosis
17
Q

How does lifestyle factors (i.e. smoking, alcohol and exercise) effect bone turnover

A
  1. Smoking
    - nicotine inhibits osteoblasts
    - inhibits intestinal absorption + kidney reabsorption
    - induces enzymes = ↓PTH and oestrogen
    - women who smoke experience earlier menopause
    - ↓appetite = weight loss = low bone mass = ↑ risk
  2. Alcohol
    - inhibits osteoblasts
    - impairs parathyroid gland = no PTH secreted in response to low Ca2+ levels of
  3. Exercise
    - puts mechanical stress on bone
    - if obese less risk of osteoporosis as muscles grow to support weight = less likely to fracture
18
Q

How does some medicines (e.g. corticosteroids) affect bone turnover

A

They↓ bone density =↑risk of osteoporosis

  1. Corticosteroids
    - BIGGEST PROBLEM
    - inhibits osteoblasts + stimulates osteoclasts
    = reabsorption / break down of bone is more than building new bone
    - ↓intestinal absorption of calcium + ↑ calcium excretion via kidneys
  2. Aromatase Inhibitors
    - used in breast cancer, oestrogen blockers = bind to OR
    - ↓oestrogen levels = no protective effects
  3. Cytotoxics
    - traditional chemo treatment kills sex steroid hormones / inhibits their production e.g. testosterone and oestrogen
    - ↓protective effects
  4. Heparin and warfarin
    - inhibits osteoblasts

Semester 1 (YEAR 3) - Lecture Notes (25 decks)

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