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Year 3 > bones > Flashcards

bones Flashcards

1
Q

Hormones that increase calcium + how are they made?

A

PTH (parathyroid glands)

Calcitriol = activated Vit D = 1,25-hydroxy vitamin D (skin + UV light)

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2
Q

Hormone that decrease calcium + how is it made?

A

Calcitonin

Produced in parafollicular cells within thyroid)

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3
Q

Explain the steps of active Vit D synthesis

A

SKIN, INTESTINES
diet + UV -> vit D

LIVER
25-hydroxylase converts to 25-hydroxy vit D

KIDNEYS
1a-hydroxylase converts to calcitriol

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4
Q

Causes of raised prolactin - the 6 p’s

A 
pregnancy
prolactinoma
physiological
polycystic ovarian syndrome
primary hypothyroidism
phenothiazines, metoclopramide, domperidone
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5
Q

Compare the effects of PTH and calcitriol on calcium and phosphate

A

PTH:
↑ Calcium
↓ ↓ Phosphate (phosphate trashing)

CALCITRIOL:
↑ ↑ Calcium
↑ Phosphate

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6
Q

State 3 organs affected by PTH and the outcome for each

A 
KIDNEYS- 
- 1α-hydroxylase stimulation
- ↑ calcium reabsorption 
- ↑ phosphate excretion
BONE- 
- ↑ bone reabsorption

SMALL INTESTINE

  • ↑ calcium absorption
  • (↑ phosphate absorption)
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7
Q

State 3 organs affected by calcitriol and the outcome for each

A 
KIDNEYS- 
- ↑ calcium reabsorption 
-(↑ phosphate reabsorption)
BONE- 
- ↑ bone reabsorption

SMALL INTESTINE

  • ↑ calcium absorption
  • ↑ phosphate absorption
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8
Q

Which hormone decreases blood calcium levels?

A

Calcitonin

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9
Q

Which hormone, out of PTH and calcitriol, raises blood calcium levels the most?

A

Calcitriol

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10
Q

Which enzyme does PTH activate in the kidneys?

A

1α-hydroxylase

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11
Q

Which hormone increases urinary phosphate excretion?

A

PTH (=phosphate trashing hormone)

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12
Q

briefly explain the parathyroid axis

A
  • decreased calcium
  • parathyroid glands produce PTH
  • PTH stimulates 1-a hydroxylase to produce more calcitriol
    calcitirol + PTH increase calcium
  • negative feedback on parathyroid glands
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13
Q

State 2 causes of primary hyperparathyroidism

A

Parathyroid adenoma

Parathyroid hyperplasia

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14
Q

State 2 causes of secondary hyperparathyroidism

A

Vitamin D deficiency
CKD
Liver disease

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15
Q

What is another term used for secondary hyperparathyroidism?

A

osteomalacia

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16
Q

What are calcium and phosphate levels in:

  • Primary hyperPTH
  • Secondary hyperPTH
  • Tertiary hyperPTH
A

Primary hyperPTH

  • ↑ calcium
  • ↓ phosphate

Secondary hyperPTH

  • ↓ calcium
  • ↓ phosphate (unless CKD = ↑ phosphate)

Tertiary hyperPTH (autonomous PTH secretion)

  • ↑ calcium
  • ↑ phosphate
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17
Q

Which two forms of hyperPTH show a high phosphate?

A

Chronic kidney disease:

  • Secondary hyperPTH
  • Tertiray hyperPTH

Kidneys cannot excrete phosphate

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18
Q

What causes tertiary hyperPTH?

A

CKD

develops from secondary hyperPTH

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19
Q

Causes of high calcium?

A

HIGH PTH CAUSES

  • Primary hyperPTH
  • Tertiary hyperPTH

LOW PTH CAUSES

Malignancy:
- Bone metastases
- Haem (multiple myeloma)
- Paraneoplastic e.g. lung
SCC

Sarcoidosis

Thiazide diuretics

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20
Q

Symptoms of hypercalcaemia

A

“stones, bones, thrones, abdominal groans and psychiatric moans”

  • Renal stones
  • Fractures, bones
  • Polyuria, polydipsia
  • Abdo- nausea, constipation, pancreatitis
  • Depression, anxiety
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21
Q

Causes of low calcium?

A

HIGH PTH CAUSES

  • Secondary hyperPTH
  • aka osteomalacia
  • aka vit D deficiency

LOW PTH CAUSES

  • surgical complications- post thyroidectomy for Grave’s
  • autoimmune hypoparathyroidism (rare)
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22
Q

Symptoms of hypocalcaemia

‘Cats go numb’

A

Convulsions
Arrhythmias (eg prolonged QT)
Tetany
Parasthesia (hands, mouth, feet, lips)

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23
Q

2 clinical signs of hypocalcaemia

A

Trousseau’s sign (carpopedal spasm caused by inflating BP cuff above SBP)
Chvostek’s sign (twitching of the facial muscles in response to tapping over facial nerve)

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24
Q

Which is more likely to be found in a pancreatitis patient: hypercalcaemia or hypocalcaemia?

A

Hypocalcaemia- due to saponification

Damage to pancreas leads to autodigestion of pancreas (autolysis)

Calcium binds to digestive ‘gunk’ + this draws out of blood

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25
Q

Will bone cancer cause high PTH or low PTH

A

Low PTH (due to negative feedback)

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26
Q

Risk factors for PT gland hyperplasia

A

MEN-1 or MEN-2

Hypertension

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27
Q

Which conditions come up in:
MEN-1 (PPP)
MEN-2 (PTP)

A

MEN-1:

  • PT hyperplasia
  • Pituitary tumours
  • Pancreatic tumours

MEN-2:

  • PT hyperplasia
  • medullary Thyroid cancer
  • Phaeochromocytoma
28
Q

signs and symptoms of hyperPTH

A

Often asymptomatic

Hypercalcaemia:
”Stones, bones, thrones, abdominal moans, psychiatric overtones”

29
Q

Define secondary hyperPTN

A

disorder of bone mineralisation

30
Q

Causes of secondary hyperPTH

A 
Vitamin D deficiency
- Poor dietary intake
- Poor sunlight
- Malabsorption
Chronic kidney disease
Liver disease
31
Q

Signs and symptoms of secondary hyperPTH

A 
ADULTS
Fractures/bone pain
Proximal myopathy
Fatigue
Hypocalcaemia:”CATs go numb”

CHILDREN (Rickets)
Bowed legs
Knock knees

32
Q

3 endocrine causes of proximal myopathy (COT)

A

Cushing’s
Osteomalacia
Thyrotoxicosis

33
Q

Investigations for hyperparathyroidism

A 
Physical examination (cardio/resp/abdo/neuro)
Basic observations

Bloods

  • (FBC, CRP)
  • U&E
  • LFTs - ALP
  • Calcium
  • Phosphate
  • PTH

Imaging

  • X-rays/CT (extent of bone disease)
  • Cervical U/S (before surgery, adenoma)
34
Q 
State the level of:
Calcium
Phosphate
PTH
ALP
in primary hyperPTH
A

Calcium ↑
Phosphate ↓
PTH ↑ (or ↔)
ALP ↔

35
Q 
State the level of:
Calcium
Phosphate
PTH
ALP
in secondary hyperPTH (osteomalacia)
A

Calcium ↓
Phosphate ↓
PTH ↑ (↓ in CKD)
ALP ↑

36
Q

What 3 signs might you see of primary hyperPTH on xray?

A
  • Subperiosteal bone resorption (usually radial)
  • Acro-osteolysis (resorption of distal phalanges)
  • Pepper pot skull (resorption by PTH)
37
Q

What do you see in x-rays of children with secondary hyperPTH?

A

Rachitic rosary = nodularity at costochondral junctions

38
Q

What do you see in x-rays of adults with secondary hyperPTH?

A

Looser’s pseudofractures
Wide, transverse lucencies with sclerotic borders traversing partway through a bone, usually perpendicular to the involved cortex

39
Q

Management of acute hypercalcaemia

A

IV fluids

Bisphosphonates (if calcium remains high)

40
Q

Management of primary hyperPTH (associated risk)

A

Total parathyroidectomy
- risk of recurrent laryngeal nerve damage (hoarseness)

If unsuitable for surgery

  • Cinacalcet
  • calcimemetic- acts to negatively feedback on PTH axis
41
Q

Management of secondary hyperPTH

A

IV calcium infusion (calcium gluconate)

also used to treat hyperkalaemia

42
Q

Management of acute hypocalcaemia

A

Medical:

  • Calcium
  • Inactive vitamin D (ergocalciferol)
  • Active vitamin D (alfacalcidol) in CKD as cannot complete second hydroxylation step
43
Q

Which hyperPTH is ALP high?

A

secondary

44
Q

Define Paget’s

A

disorder of bone remodelling (i.e. formation and resorption) – genetic factors play a role

45
Q

3 phases of Paget’s

A

LYTIC PHASE- hyperactive osteoclasts > resorption
SCLEROTIC PHASE- compensation by osteoblasts
MIXED PHASE- hyperactive osteoblasts > formation
(woven bone, not lamellar)

So you get lots of immature bone leading to pain, fragility fractures

46
Q

RF for Paget’s

A

Elderly

FHx

47
Q

Number of bones affected by Paget’s

A

25% of cases: monostotic

75% of cases: polyostotic

48
Q

Symptoms of Paget’s

A

Often asymptomatic

  • Fragility fractures
  • Bone pain (insidious onset)- skull, pelvis, femur

Nerve compression- due to narrowing of foramina

  • Hearing loss (sensorineural- vestibulococular nerve)
  • Sciatica
49
Q

Signs of Paget’s

A

Bone enlargement/bossing

Warm skin over painful area (high metabolic activity)

50
Q

Investigations for Paget’s

A

Bloods

  • (FBC, CRP)
  • U&E
  • LFTs (ALP)
  • Calcium
  • Phosphate
  • PTH
  • Serum CTX (bone resorption marker)
  • Serum P1NP (bone formation marker)

Imaging
- X-rays
- Bone scan- a type of nuclear medicine imaging test- using Tech99 tracer
Looks at areas of increased metabolic activity

51
Q 
State the level of:
Calcium
Phosphate
PTH
ALP
in Paget's
A

Calcium ↔
Phosphate ↔
PTH ↔
ALP ↑↑

52
Q

define osteoporosis

A

low BMD

53
Q

RF for osteoporosis (primary and secondary causes)

A

PRIMARY
Post-menopausal
Elderly

SECONDARY
Drugs – steroids, thyroxine, alcohol
Endo – Cushing’s disease, hyperPTH, hyperT
GI – coeliac disease, IBD (malabsorption > low vitD)

54
Q

Signs and symptoms of osteoporosis

A

Often asymptomatic

Fragility fractures
Back pain

55
Q

Classic fractures in osteoporosis

A

Hip – neck of femur (NOF)
Wrist – Colles’ fractures
Lumbar spine - vertebral wedge fractures (these can be asymptomatic- explain why older people ‘shrink’)
Shoulder - neck of humerus

56
Q 
State the level of:
Calcium
Phosphate
PTH
ALP
in osteoporosis
A

EVERYTHING NORMAL

57
Q

Investigations for osteoporosis

A 
Bloods
(FBC, CRP)
U&E
LFTs (ALP)
Calcium
Phosphate
PTH

Imaging

  • X-rays
  • DEXA scan
58
Q

2 scores used to diagnose osteoporosis. Which one is more useful?

A

T-score: Patient’s BMD compared to young, healthy adult
Z-score: Patient’s BMD compared to age-matched BMD

T-score is used more often:
>-1.0 = normal
-1.0 and -2.5 = osteopaenia

59
Q

What is T score used to calculate?

A

FRAX score:
10 year risk of developing fragility fractures
Which can help decide if Tx is required

60
Q

A 42 year old Pakistani woman attends her GP appointment. She has been experiencing non-specific pain in her legs alongside muscle weakness for a month. Her X-ray shows Looser’s pseudofractures

What is the most appropriate treatment option?

A Increase calcium intake in diet
B Bisphosphonates 
C Calcium and vitamin D supplements
D Total parathyroidectomy
E Recombinant PTH
A

Calcium and vitamin D supplements

diagnosis = osteomalacia
“Pakistani/Arabic women” is a common buzzword for vitamin D deficiency (due to the unfair generalisation that these women will be wearing hijabs and thus will not produce enough vitamin D from sunlight)

61
Q

Treatment of osteoporosis/pagets

A

bisphosphonates (alendronic acid)

62
Q

A 58 year old post-menopausal woman was diagnosed with a fragility fracture. Her past medical history includes a myocardial infarction at the age of 47, and rheumatoid arthritis for which she is taking prednisolone. Her blood results are normal

What is the most likely underlying diagnosis?

A Osteomalacia
B Primary hyperparathyroidism
C Paget’s disease
D Tertiary hyperparathyroidism
E Osteoporosis
A

osteoprosis- RF:
Steroids can cause osteoporosis
Menopause can cause osteoporosis (since oestrogen is protective of bones)

63
Q

In which 2 bone conditions is calcium normal?

A

osteoporosis

Pagets

64
Q

In which bone condition is calcium low?

A

osteomalacia / secondary hyperPTH

65
Q

In which bone conditions is calcium high?

A

primary/tertiary hyperPTH, malignancy

Year 3 (38 decks)

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