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PM3B: Autumn > Metabolic Bone Disorders: Osteoporosis > Flashcards

Metabolic Bone Disorders: Osteoporosis Flashcards

1
Q

What is osteoporosis

A

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

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2
Q

What is the most common complication of osteoporosis

A

Hip fractures

Fracture of wrists, vertebrate and humerus

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3
Q

How is osteoporosis classified

A

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

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4
Q

What are the risk factors of osteoporosis

A

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

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5
Q

How do you prevent osteoporosis

A

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

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6
Q

How do you diagnose osteoporosis

A

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

Previous fracture and over 75

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7
Q

When do you take a patient in for a DEXA scan

A

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

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8
Q

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

A

BISPHOSPHONATES

Example:
ALDEDRONIC ACID
RISEDRONATE SODIUM

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9
Q

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

A

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)

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10
Q

What is the role and mechanism of action of bisphosphonates

A

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)

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11
Q

What are the side effects of bisphosphonates

A

Gastrointestinal side effects

Severe oesophageal reaction and stricture

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12
Q

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

A

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

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13
Q

What is found in patients given bisphosphonates via IV

A

Osteonecrosis of jaws- death of jawbone

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14
Q

What is the dose of bisphosphonates in men and women

A

Women: 10mg or 70mg ONCE daily

Men: 10mg ONCE daily

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15
Q

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

A

Oestrogen

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

Risk: cancer

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16
Q

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

A

RALOXIFENE

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

Risk: increased risk of venous thromboembolism

17
Q

When can strontium ranelate be used and its mechanism of action

A

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
Q

What is the mechanism of action of calcitonin and its role

A

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
Q

What is role of PTH (parathyroid hormone)

A

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

20
Q

Give an example of PTH

A

Teriparatide

21
Q

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

A

Glucocorticoids- cortisol

Mineralocorticoids- aldosterone

22
Q

How do corticosteroids induce osteoporosis

A

Use of excessive pharmacological concentrations inhibits bone formation by inhibiting OSTEOBLASTS

Also may stimulate OSTEOCLAST action

23
Q

How do you reduce risk of corticosteroid induced osteoporosis

A

DOSE: Low as possible and shortest course of treatment

Take calcium or vitamin D supplements

24
Q

What is Calcitriol

A

Vitamin D3 analogue

25
Q

What is Paget’s disease of bone

A

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

Bones enlarge, become structurally abnormal and weaker than normal

26
Q

What are the symptoms of Paget’s disease

A

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
Q

How do you treat paget’s disease

A

Bisphosphonates:
Risedronate sodium- 30mg daily for 2 months

Calcitonin: 50 units THREE times a week

NSAIDS for pain

28
Q

How does rickets occur in children

A

Lack of sunlight exposure

Lack of vitamin D in diet

29
Q

How does Osteomalacia occur in adults

A

Vitamin D deficiency

30
Q

What can vitamin D deficiency lead to

A

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
Q

What is the role of vitamin D

A

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
Q

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

A

Vitamin D2- diet

Vitamin D3- colecalcifediol- sunlight

33
Q

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

A
  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
Q

What are the symptoms of osteomalacia and rickets

A

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
Q

What are the causes of osteomalacia or rickets

A

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
Q

How do you treat rickets or osteomalacia

A

Calcium and vitamin D supplements

PM3B: Autumn (19 decks)

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