Metabolic Bone Disorders: Osteoporosis Flashcards Preview

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Flashcards in Metabolic Bone Disorders: Osteoporosis Deck (36):
1

What is osteoporosis

Low bone mass and derivation of microarchitecture of bone tissue (loss of spongy bone)

2

What is the most common complication of osteoporosis

Hip fractures

Fracture of wrists, vertebrate and humerus

3

How is osteoporosis classified

T score- number of standard deviations that a patients bone mass measurement is from

Normal:
T score > -1

Osteopoenia:
T score -1 to -2.5

Osteoporosis:
T score below -2.5

Established osteoporosis
T score

4

What are the risk factors of osteoporosis

Age- 50

Gender- most case it is women

Slight build, low BMI

Untreated premature menopause
Prolonged amenorrhoea
Male hypogondaism

ALCOHOL

Smoking

Corticosteroid use

Family history- mothers side of the family with hip fracture

Other conditions-
Inflammatory bowel or coeliac disease
Hyperthyroidism
Renal failure

5

How do you prevent osteoporosis

Lifestyle modification:

Regular weight bearing exercise

Stopping smoking before menopause

Maintain adequate levels of calcium and vitamin D (700mg per day)

Reduce alcohol consumption

Maintain BMI >19kg/m2

6

How do you diagnose osteoporosis

DEXA scan- Dual Energy Xray Absorptionmetry
(low energy x rays penetrate less dense bone better)

Previous fracture and over 75

7

When do you take a patient in for a DEXA scan

previous fracture and over 75

Risk factors of osteoporosis

Osteopenia x ray done

Long term steroid use with calcium and vitamin D supplements and over 65

8

What is the first line treatment option available for osteoporosis and give an example of it

BISPHOSPHONATES

Example:
ALDEDRONIC ACID
RISEDRONATE SODIUM

9

What other treatment options other than the first line is available for osteoporosis

Hormone replacement therapy for over 50's

RALOXIFENE- selective oestrogen receptor modulator

Strontium Ranelate- over 75 years with previous condition and low BMD (bone mineral density)

Use of calcitonin

Teriparatide over 65 years (Low BMD)

10

What is the role and mechanism of action of bisphosphonates

Enzyme resistant analogue of pyrophosphate that inhibits bone reabsorption

50% binds at sites of bone mineralisation where they stop the osteoclasts from breaking down the bone (they are ingested instead of bone by osteoclasts)

11

What are the side effects of bisphosphonates

Gastrointestinal side effects

Severe oesophageal reaction and stricture

12

What should you avoid when taking bisphosphonates and what reduces its absorption (drug wise)

Do not take at bed time

Avoid food before and after dose as it impairs absorption- at least 30 minutes

Antacids, calcium salts and iron reduce absorption

13

What is found in patients given bisphosphonates via IV

Osteonecrosis of jaws- death of jawbone

14

What is the dose of bisphosphonates in men and women

Women: 10mg or 70mg ONCE daily

Men: 10mg ONCE daily

15

What is found in hormone replacement therapy, its role and the risk

Oestrogen

Role:
Maintenance of bone integrity by inhibition of cytokines which recruit osteoclasts and opposing bones reabsorption (Ca2+)

Risk: cancer

16

Give an example of a selective oestrogen receptor modulator (SERM), role of action and the risk

RALOXIFENE

Selective agonist activity on bone and cardiovascular system and antagonist activity on mammary tissue and uterus

Risk: increased risk of venous thromboembolism

17

When can strontium ranelate be used and its mechanism of action

Post menopausal osteoporosis or women with high risk fracture (over 75 years)

Inhibition of bone reabsorption
through being adsorbed into hydroxyapatite crystals in bone in exchange for Ca2+ in mineralised bone

18

What is the mechanism of action of calcitonin and its role

Maintaining calcium homeostasis and bone

MoA:
Inhibition of osteoclast action directly via specific receptors
Decreases plasma Ca2+ and decreases reabsorption of Ca2+ and phosphate in kidney

19

What is role of PTH (parathyroid hormone)

Increases osteoclast number
Stimulates their activity
Increases bone mass, integrity and strength
Decrease in osteoblast apoptosis

20

Give an example of PTH

Teriparatide

21

What are the two different types of corticosteroids and what biomarkers do they imitate in the body

Glucocorticoids- cortisol

Mineralocorticoids- aldosterone

22

How do corticosteroids induce osteoporosis

Use of excessive pharmacological concentrations inhibits bone formation by inhibiting OSTEOBLASTS

Also may stimulate OSTEOCLAST action

23

How do you reduce risk of corticosteroid induced osteoporosis

DOSE: Low as possible and shortest course of treatment

Take calcium or vitamin D supplements

24

What is Calcitriol

Vitamin D3 analogue

25

What is Paget's disease of bone

Areas of bone undergoing accelerated bone remodelling due to hyperactivity of osteoblasts and osteoclasts

Bones enlarge, become structurally abnormal and weaker than normal

26

What are the symptoms of Paget's disease

Bone aching- worse at rest or night

Bone enlargement: skull, spine and pelvis

Deformity
Changes in adjacent joint structure leading to osteoarthritis (wear and tear)

Hypercalcaemia:
Increased hypertension, kidney stones, muscle weakness
Increased blood flow- heart failure

27

How do you treat paget's disease

Bisphosphonates:
Risedronate sodium- 30mg daily for 2 months

Calcitonin: 50 units THREE times a week

NSAIDS for pain

28

How does rickets occur in children

Lack of sunlight exposure

Lack of vitamin D in diet

29

How does Osteomalacia occur in adults

Vitamin D deficiency

30

What can vitamin D deficiency lead to

Decreased plasma calcium and phosphate levels (impacts bone)

Increased plasma Ca2+ levels lead to PTH levels increasing and depletion of calcium stores in bone (soft weak bone)

31

What is the role of vitamin D

Maintaining plasma Ca2+ by increasing absorption in intestine and kidney

Mobilising it from bone- increase osteoclast maturation and activity (decrease renal excretion)

Decreases osteoblast synthesis in collagen

32

What are the two forms of vitamin D and where can they be obtained

Vitamin D2- diet

Vitamin D3- colecalcifediol- sunlight

33

What does low vitamin D means for the body in calcium homeostasis

1. Low blood Ca2+ levels

2. Stimulates PTH secretion

3. PTH acts on kidney, large intestine, bone to increase blood Ca2+

4. Increased blood Ca2+

34

What are the symptoms of osteomalacia and rickets

Bone pain and tenderness

Skeletal deformity:
Bow legs
Pigeon Chest
Spinal deformity

Dental deformities

Muscular problems- weakness, cramps

Impaired growth

Low calcium- hands and feet spasms

35

What are the causes of osteomalacia or rickets

Dietary deficiency- dark skin living in northern climates

Age related- vitamin D metabolism decreases with age

Secondary rickets/osteomalacia- liver disease or renal failure

Vitamin D dependent rickets- decreased renal absorption of phosphate

36

How do you treat rickets or osteomalacia

Calcium and vitamin D supplements