Metabolic Bone Disorders: Osteoporosis

Question 1

What is osteoporosis

Answer 1

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

Question 2

What is the most common complication of osteoporosis

Answer 2

Hip fractures

Fracture of wrists, vertebrate and humerus

Question 3

How is osteoporosis classified

Answer 3

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

Question 4

What are the risk factors of osteoporosis

Answer 4

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

Question 5

How do you prevent osteoporosis

Answer 5

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

Question 6

How do you diagnose osteoporosis

Answer 6

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

Previous fracture and over 75

Question 7

When do you take a patient in for a DEXA scan

Answer 7

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

Question 8

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

Answer 8

BISPHOSPHONATES

Example:
ALDEDRONIC ACID
RISEDRONATE SODIUM

Question 9

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

Answer 9

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)

Question 10

What is the role and mechanism of action of bisphosphonates

Answer 10

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)

Question 11

What are the side effects of bisphosphonates

Answer 11

Gastrointestinal side effects

Severe oesophageal reaction and stricture

Question 12

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

Answer 12

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

Question 13

What is found in patients given bisphosphonates via IV

Answer 13

Osteonecrosis of jaws- death of jawbone

Question 14

What is the dose of bisphosphonates in men and women

Answer 14

Women: 10mg or 70mg ONCE daily

Men: 10mg ONCE daily

Question 15

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

Answer 15

Oestrogen

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

Risk: cancer

Question 16

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

Answer 16

RALOXIFENE

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

Risk: increased risk of venous thromboembolism

Question 17

When can strontium ranelate be used and its mechanism of action

Answer 17

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

Question 18

What is the mechanism of action of calcitonin and its role

Answer 18

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

Question 19

What is role of PTH (parathyroid hormone)

Answer 19

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

Question 20

Give an example of PTH

Answer 20

Teriparatide

Question 21

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

Answer 21

Glucocorticoids- cortisol

Mineralocorticoids- aldosterone

Question 22

How do corticosteroids induce osteoporosis

Answer 22

Use of excessive pharmacological concentrations inhibits bone formation by inhibiting OSTEOBLASTS

Also may stimulate OSTEOCLAST action

Question 23

How do you reduce risk of corticosteroid induced osteoporosis

Answer 23

DOSE: Low as possible and shortest course of treatment

Take calcium or vitamin D supplements

Question 24

What is Calcitriol

Answer 24

Vitamin D3 analogue

Question 25

What is Paget's disease of bone

Answer 25

Areas of bone undergoing accelerated bone remodelling due to hyperactivity of osteoblasts and osteoclasts Bones enlarge, become structurally abnormal and weaker than normal

Question 26

What are the symptoms of Paget's disease

Answer 26

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

Question 27

How do you treat paget's disease

Answer 27

Bisphosphonates: Risedronate sodium- 30mg daily for 2 months Calcitonin: 50 units THREE times a week NSAIDS for pain

Question 28

How does rickets occur in children

Answer 28

Lack of sunlight exposure Lack of vitamin D in diet

Question 29

How does Osteomalacia occur in adults

Answer 29

Vitamin D deficiency

Question 30

What can vitamin D deficiency lead to

Answer 30

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)

Question 31

What is the role of vitamin D

Answer 31

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

Question 32

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

Answer 32

Vitamin D2- diet Vitamin D3- colecalcifediol- sunlight

Question 33

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

Answer 33

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+

Question 34

What are the symptoms of osteomalacia and rickets

Answer 34

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

Question 35

What are the causes of osteomalacia or rickets

Answer 35

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

Question 36

How do you treat rickets or osteomalacia

Answer 36

Calcium and vitamin D supplements