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Diabetes & Endocrine > Osteoporosis > Flashcards

Osteoporosis Flashcards

1
Q

What molecule reabsorbs bone cells?

A

Osteoclasts

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2
Q

What molecule forms bone cells?

A

Osteoblasts

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3
Q

What are the 3 compounds that control Ca lvls.

A

PTH, Calcitonin, Vitamin D.

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4
Q

What can Hypocalcaemia cause?

A

Increases muscle/nerve excitability, muscles spams of the respiratory muscles.

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5
Q

What can hypercalcaemia cause?

A

Decrease in muscle/nerve excitability, can cause cardiac arythmias.

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6
Q

What does RANKL do?

A

Increases osteoclast differentiation and decreases osteoclast apoptosis -> increasing their number and promoting bone resorption over long term.

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7
Q

What does Osteoprotegrin do?

A

Decoy receptor for RANKL. Decreases osteoclast number and promotes bone deposition over long term.

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8
Q

What effect does PTH have on fast exchange?

A

Rapid efflux of Ca2+ from small labile pool. Increase in cAMP -> movement of Ca2+ into cells from the bone fluid.

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9
Q

What effect does PTH have on slow exchange?

A

Activates osteoblasts to increase RANKL expression. Osteoclats increase bone resportion, which increases plasma [Ca]. Osteoblast building in inhibited.

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10
Q

What effect does PTH have on the kidneys?

A

Promote Ca retnetion (Ca2+ reabsorption occurs). Promotes PO43- excretion (decreases reabsorption). Causes an activation of vitamin D in the kindeys.

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11
Q

What does calcitonin do?

A

Antagonistic hormone to PTH. Secretion increased when there is an increase in [Ca2+]. Acts to decrease lvls of extracellular plasma by decreasing Ca2+ movement from the canaliculi fluid into the plasma. Inhibiting osteoclast activity.

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12
Q

What does vitamin D do?

A

Pre-hormone that increases Ca2+ absorption in the GIT.

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13
Q

Where in the body is Vitamin D activated in the body?

A

An OH group is added in the liver to form Calcifediol which is then stored until required.
Then another OH group is added in the kidney to form Calcitrol which is caused by PTH.

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14
Q

What does activated vitamin D do?

A

Acts as a nuclear receptor which causes transcription factor promoting gene expression. Which causes an increased absorption of Ca2+ in the GIT, increasing plasma Ca2+ and restoring Ca balance.

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15
Q

What is bone remodelling?

A

Where old bone is removed and replaced by new bone.

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16
Q

Osteoblast.

A

Fill in bony cavity with bone matrix & release cytokines to attract osteoclasts.

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17
Q

Osteoclast.

A

Release proteases which dissolve bone mineral matrix and collagen. releases chemical that attract osteoblasts.

18
Q

What molecules control bone remodelling?

A

PTH, Activated vitamin D, IL-1, IL-6, TNF-alpha, GCSF.

19
Q

What can cause bone loss?

A

Low Ca2+ intake, low exposure to sunlight, Alcohol, smoking, thin body type.

20
Q

What is osteoporosis?

A

Common metabolic bone disease characterised by reduction in bone mass per unit volume that occur with increasing age.

21
Q

What can you use to detect osteoporosis?

A

Dual energy X-ray absorptiometry (DEXA). Allows for acurate and reproducible mreasurement of BMD.

22
Q

What is primary osteoporosis?

A

When patient has no other disorders known to cause osteoporosis.

23
Q

Whar is secondary osteoporosis?

A

Osteoporosis due to another medical condition, Anorexia, IBD, Endocrine, RA.
Use of steroid therapy too.

24
Q

What do corticosteroids do?

A

Decrease osteoblast activity.
Decrease Ca absorption from intestine and increase renal Ca loss.

25
Q

most common symptoms of osteoporosis?

A

Fractures at the vertebra, distal radius, neck of femur.

26
Q

People at risk of menopause.

A

Postmenopausal women
Low BMI
Untreated premature menopause
Conditions affecting bone metabolism
Prolonged immonility/sedentary lifestyle.
Alchol & smoking.

27
Q

What are the Guideline groups for osteoporosis?

A

Low - Lifestyle + calcium/Vitamin D
Intermediate Risk - Assess BMD with DEXA scan
High Risk - Consider start treatment without need for BMD assessment.

28
Q

What are the lifestyle changes?

A

Regular exercises
Aim to take 3-4 portions of Ca-rich foods daily.
Vatmin D - exposure to sunlight, dietry intake of 400 units daily.

29
Q

What are the drug treatmenet options for Osteoporosis?

A

Firstline :
Bisphosphonates.

Second line :
Denosumab
Faloxifene
Teriparatide
Strontium
HRT
Romosozumab

30
Q

Name different Bisphosphonates and the dosage.

A

Alendronate - Daily / Weekly
Risedronate - Daily / Weekly
Ibandronate - Oral monthyl, IV 3 monthly.
Zolendronate - Annual IV

31
Q

What are the counselling points for Bisphosphinates?

A

Take on an empty stomach
Swallow whole with full glass of plain water
Remain upright for at least 30 mins
Dont lie down until after eating breakfast

32
Q

What are the side effects of Bisphosphonates?

A

Osteonecrosis of the jaw.
Atypical femoral fractures.
Osteonecrosis of the external auditory canal.

33
Q

Name the drugs given in steroid induced osteoporosis?

A

First line :
Alendronate / Risedronate

Second Line :
Zolendronate
Denosumab
Teriparatide.

34
Q

Treatment of vitamin D deficiency?

A

Colecalciferol - 400 units
Loading dose :
50,000 units once weekly for 6 weeks
40,000 units once weekly for 7 weeks
4000 units daily for 10 weeks
Maintenance dose :
800-2000 units daily to start 1 month after LD completed.

35
Q

What is the MOA of Bisphosphinates?

A

Binds to Ca2+ in bone, released as bone is resorbed, Main action is on osteoclasts. Reduce rate of bone turnover.

36
Q

What is the MOA of Raloxifene?

A

SERM, Mixed agonist/antagonist at oestrogen receptors, Stimulates osteoblasts activity inhibits osteoclast activity. Blocks receptors on mammary and uterine tissues.

37
Q

What is the MOA of denosumab?

A

Monoclonal antibody to RANKL
Inhibits binding of RANKL to RANK.

38
Q

What is the MOA of Calcitonin?

A

Has the same effect as endogenois calcitonin.

39
Q

What is the MOA of Teriparatide?

A

Activate fragments of PTH, Acts at PTH receptors, Paradoxiaclly has opposite effects to PTH.

40
Q

What is the MOA of strontium?

A

Increases the sensitivity of the Ca sensing receptor in the parathyroid cells.
Decreases PTH secretion.

Diabetes & Endocrine (7 decks)

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