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Year 2- Endocrine System > Clinical Calcium Homeostasis > Flashcards

Clinical Calcium Homeostasis Flashcards

1
Q

LIST SOME DIETARY SOURCES OF CALCIUM WHOOOOOOOOOOOOOOOOOO GO GIRL GO

A

Milk, cheese, dairy
Green leafy veg
Soya beans
Tofu
Nuts
Fish w bones e.g sardines and pilchards.
Anything w fortified flour

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2
Q

List the functions of calcium.

A

Bone formation
Cell division and growth
Muscle contraction
Neurotransmitter release

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3
Q

80% approx. of calcium consumed through diet is not absorbed. Why?

A

Forms insoluble salts e.g. calcium phosphate or calcium oxalate which cannot be absorbed by the body

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4
Q

Where is the majority of the body’s calcium kept and stored?

A

Bone

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5
Q

What proportion of calcium in the plasma is bound?

A

40% bound to plasma proteins
15% non-ionised or bound to complexes
45% free/ionised

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6
Q

What is normal plasma calcium range?

A

2.2-2.6 mmol/l

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7
Q

If there is increased albumin, what does this tell us about free calcium levels?

A

Decreased

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8
Q

If there is decreased albumin, what does this tell us about free calcium levels?

A

Increased

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9
Q

Acidosis increases ionised calcium. What can this predispose to?

A

Hypercalcaemia

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10
Q

In which conditions would there be low albumin?

A

Malnutrition
Nephropathy

-> conditions in which patients lose a lot of protein in their urine

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11
Q

Food sources of vitamin D?

A

Oily fish
Fortified fat spreads
Eggs
Fortified breakfast cereals

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12
Q

What is the best source of vitamin D?

A

The sun

-> the body must be exposed sufficiently to strong sunlight in order to get vitamin D

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13
Q

Which groups of people are at higher risk of a vitamin D deficiency?

A

Pregnant
Children
Those in care
Those who don’t get much sunlight
Those with darker skin tone

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14
Q

How many parathyroid glands do we have?

A

4

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15
Q

Parathyroid glands contain chief cells. What do these cells secrete?

A

PTH

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16
Q

When calcium levels increase, what happens to PTH level?

A

Decease

-> and vice versa

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17
Q

How does PTH increase calcium levels?

A

Promotes calcium reabsorption from renal tubules and bone

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18
Q

Which form of vitamin D is primary obstained?

A

Vitamin D3

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19
Q

What happens to vitamin D3?

A

Hydroxylated in the liver to form 25-hydroxyvitamin D which is an inactive form of vitamin D

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20
Q

What is inactive vitamin D then activated into?

A

1,25- dihydroxyvitamin D

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21
Q

List some of the acute neuromuscular features of hypocalcaemia.

A

Paraesthesia
Muscle twitching
Seizures
Laryngospasm
Bronchospasm
Trosseau’s sign
Chovtek’s sign

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22
Q

Trousseau’s sign is associated with hypocalcaemia, what is it?

A

A sign of latent tetany used to determine hypocalcaemia

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23
Q

What is Chvostek’s sign?

A

Twitch of facial muscles that occurs when gently tapping an individual’s cheek, it indicates hypocalcaemia

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24
Q

What are some of the cardiac features of acute hypocalcaemia?

A

Prolonged QT interval
Hypotension
Heart failure
Arrhythmia
Papilledema

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25
Q

What are some of the features of chronic hypocalcaemia?

A

Ectopic calcification
Parkinsonism
Dementia
Dry skin
Abnormal dentition
Subcapsular cataracts

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26
Q

At which level of calcium do the features of hypocalcaemia tend to arise?

A

If calcium levels drop below 1.9mm/l

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27
Q

List some of the causes of hypocalcaemia.

A

Disruption of parathyroid gland, usually due to total thyroidectomy
Severe vitamin D deficiency
Magnesium deficiency
Cytotoxic drug-related hypocalcaemia
Pancreatitis
Large volume blood transfusions

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28
Q

Which drug can cause magnesium deficiency?

A

Omeprazole

29
Q

Which investigations would be carried out if you suspected hypocalcaemia?

A

ECG
Serum calcium
Albumin levels
Phosphate levels
PTH
U&Es
Vitamin D
Magnesium

30
Q

What is th first thing to check in someone with hypocalcaemia?

A

PTH

->can be low or high in hypocalcaemia

31
Q

What is the appropriate level of PTH is response to hypocalcaemia?

A

PTH levels should be high

32
Q

List some of the causes of hypocalcaemia in which PTH levels would be low.

A

Genetic disorders
Post-surgical
Autoimmune

33
Q

List some of the causes of hypocalcaemia in which PTH levels would be high.

A

Vitamin D deficiency
Renal disease
Acute pancreatitis
Acute respiratory alkalosis
Pseudohypoparathyroidism

34
Q

If someone has hypocalcaemia and low PTH levels, what would you check next?

A

Magnesium levels

35
Q

If someone has hypocalcaemia and high PTH levels, what would you check next?

A

Urea and creatine

-> if high, renal failure. If normal, check vitamin D

36
Q

What are the levels of the following in a vitamin D deficiency?
1. Calcium
2. Phosphate
3. PTH

A
  1. Low
  2. Low
  3. High
37
Q

What are the levels of the following in hypoparathyroidism?
1. Calcium
2. Phosphate
3. PTH

A
  1. Low
  2. High
  3. Low
38
Q

Hypoparrathyroidism?

A

Inappropriately low PTH in the context of hypocalcaemia

39
Q

What are some of the causes of hypoparathyroidism?

A

Post surgery
Autoimmune

40
Q

Pseudohypoparathyroidism?

A

Group of heterogenous disorders defined by target organs (bone and kidney) having unresponsiveness to PTH

41
Q

In pseudohypoparathyroidism, what are PTH levels like?

A

Elevated

42
Q

What is the classical clinical feature of pseudohypoparathyroidism?

A

Shortening of the fourth and fifth metacarpals

43
Q

What is the treatment for mild hypocalcaemia?

(asymptomatic, >1.9mmol/l)

A

Oral calcium tablets
If vit D deficient, start tablets
If low Mg, replace Mg

44
Q

What is the treatment of severe hypocalcaemia?

(symptomatic or <1.9mm/l)

A

IV calcium gluconate
Initial bolus
Initial bolus repeated until patient is asymptomatic or levels significantly increased

This is a medical emergency

45
Q

What does the Scottish government recommend the public do regarding vitamin D?

A

Those five and above should consider taking a daily vit.D supplement of 10mg, particularly during Oct-Mar.

46
Q

What can be said about a calcium level <3.0mmol/l?

A

Patient has hypercalcaemia. Often asymptomatic at this stage but usually requires urgent correction

47
Q

What can be said about a calcium level 3.0-3.5mmol/l?

A

Patient has hypercalcaemia.
May be well tolerated if risen slowly.
May be symptomatic and prompt treatment usually indicated.

48
Q

What can be said about a calcium level >3.5mmol/l?

A

The patient has hypercalcaemia.
Requires urgent correction due to risk of dysrhythmia and coma

49
Q

What are some of the more common causes of hypercalcaemia?

A

Primary hyperparathyroidism
Hypercalcaemia of malignancy

50
Q

Which medications can cause hypercalcaemia?

A

Thiazide diuretics
Very high calcium and vit.D supplements

51
Q

What are some of the renal features of hypercalcaemia?

A

Polyuria
Polydipsia
Nephrolithiasis-kidney stones

52
Q

What are some of the GI features of hypercalcaemia?

A

Anorexia
Nausea and vomiting
Constipation
Pancreatitis

53
Q

What are some of the MSK features of hypercalcaemia?

A

Muscle weakness
Bone pain
Potentially osteoporosis

-> the overall symptoms can be described as ‘bones, stones and psychic moans’.

54
Q

In hypercalcaemia, what is the appropriate response to PTH?

A

PTH low

55
Q

Who is more likely to get primary hyperparathyroidism?

A

Female > male
Incidence peak 50-60 yrs

56
Q

What are the symptoms of primary hyperparathyroidism?

A

Bit of a trick question as usually asymptomatic at diagnosis

57
Q

Which investigations are used to confirm the diagnosis of primary hyperparathyroidism?

A

Ca, PTH
U&Es
Abdominal imaging to check renal calculi
DEXA to check for osteoporosis
Spot urinary calcium/creatine ratio
24hr urinary calcium
Vitamin D

58
Q

Parathyroid imaging is not done to make a diagnosis but helps to localise adenoma so surgeons can have a targeted approach.
In those <65, which two imaging techniques are carried out?

A

Ultrasound of parathyroid glands
Sestamibi scan (nuclear)

59
Q

In those over 65, what would be the imaging of choice in primary hyperparathyroidism to look for an adenoma?

A

CT scan

60
Q

List some features that would be indicative for parathyroid surgery.

A

Any presence of symptoms
A serum calcium >0.25mmol/l above upper limit of normal
History pf osteoporosis or vertebral fractures
Renal dysfunction
<50yrs

61
Q

What is the medical management of primary hyperparathyroidism?

A

Generous fluid intake
Vitamin D replacement
Cincalcet (mimics effect of calcium on the calcium sensing receptor in chief cells leading to a fall in PTH and subsequently calcium levels).

62
Q

FFH (familial hypocalciuric hypercalcaemia)?

A

Autosomal dominant disorder of the calcium sensing receptor

63
Q

What is the treatment of FFH?

A

No treatment required usually as only mild hypercalcaemia

64
Q

What is MEN type 1?

A

Hereditary condition associated with tumours of the endocrine glands

65
Q

Which type of tumours may MEN 1 encompass?

A

Primary hyperparathyroidism
Pancreatic
Pituitary

66
Q

Which type of cancer does MEN type 2A typically present with?

A

Medullary thyroid cancer

67
Q

What is involved in the management of hypercalcaemia?

A

Rehydration
IV bisphosphonates

68
Q

List some of the potential second line treatments for hypercalcaemia.

A

Glucocorticoids
Calcitonin
Calimemetrics
Parathyroidectomy

69
Q
A

Year 2- Endocrine System (27 decks)

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