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Endocrinology > Parathyroid > Flashcards

Parathyroid Flashcards

1
Q

Where is the parathyroid?

A

4 small glands posterior to the thyroid

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2
Q

What does the parathyroid do?

A

Control levels of calcium and phosphate in the blood

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3
Q

Which needs to be more tightly:

  • calcium
  • phosphate?
A

Calcium

Phosphate levels can vary 2-3x the normal levels without causing major problems

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4
Q

What is the role of calcium in the body?

A

Contraction of skeletal, cardiac, smooth muscle

Blood clotting

Nerve impulses

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5
Q

What is the effect on the nervous system of:

  • raised calcium
  • low calcium?
A

Raised = depression of nervous system

Low = excitation of nervous system

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6
Q

Histological structure of parathyroid?

A

Chief cells that secrete PTH

Oxyphil cells: unknown function

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7
Q

What does PTH do?

A

Raise blood calcium

Lower blood phosphate

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8
Q

How does PTH raise serum calcium?

A

Indirectly stimulates osteoclasts to break down bone releasing Ca into blood

Increasing Ca reabsorption in kidney

Increasing Ca absorption in s. intestine

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9
Q

Which bone cells does PTH act on?

A

Indirectly stimulates osteoclasts to break down bone releasing Ca

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10
Q

What happens if PTH is raised for a long time?

A

It will cause proliferation of osteoclasts and greater activation of the osteoclasts already present.

This will increase breakdown of bone, and increase serum calcium and phosphates

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11
Q

How does PTH reduce serum phosphate?

A

Increased excretion from kidneys

Increased absorption of phosphate from gut and bone

BUT a net loss of phosphate

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12
Q

Reasons why serum calcium could be raised?

A

Increased dietary intake of Ca or vitamin D

Excess bone absorption, due to tumour, inactivity, hyperparathyroidism

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13
Q

Which hormone counteracts PTH? Where does it come from?

A

Calcitonin, from the C cells in thyroid

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14
Q

What does calcitonin do?

A

Lowers serum calcium if levels are raised

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15
Q

Which is more important in the regulation of calcium:

  • calcitonin
  • PTH?
A

PTH

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16
Q

Primary hyperparathyroidism:

  1. what will PTH levels be like?
  2. what will Ca levels be like?
  3. causes?
A
  1. High/normal PTH levels
  2. High calcium
  3. adenoma or hyperplasia of one of the parathyroid glands
17
Q

Clinical features of primary hyperparathyroidism?

A

Asymptomatic

Bones
Stones
Abdominal groans
Psychic moans

18
Q

What’s meant by psychic moans?

A

Due to effects on CNS, so depression, lethargy, psychosis

Things that might cause moans?

19
Q

Investigations of primary hyperparathyroidism?

A

Bloods: hypercalcaemia

MRI of neck may show mass?

20
Q

Management of primary hyperparathyroidism?

A

Removal of adenoma

21
Q

Secondary hyperparathyroidism:

  1. what will PTH levels be like?
  2. what will Ca levels be like?
  3. causes?
A
  1. high PTH
  2. low Ca
  3. a result of hypocalcaemia, the parathyroid tries to compensate by releasing more PTH, it becomes hyperplastic
22
Q

Reasons why serum calcium could be low?

A

Calcium or Vitamin D deficiency

Excess Mg2+

Hypoparathyroid

Renal disease, CKD

23
Q

Clinical features of secondary hyperparathyroidism?

A

Kidney disease

Skeletal or CVS complications

24
Q

Investigations of secondary hyperparathyroidism?

A

Bloods: low serum calcium

Evidence of underlying cause, e.g. renal failure

25
Q

Management of secondary hyperparathyroidism?

A

Correct low calcium, to prevent parathyroid having to work extra hard

Treat underlying cause

26
Q

Tertiary hyperparathyroidism:

  1. what will PTH levels be like?
  2. what will Ca levels be like?
  3. causes?
A
  1. high PTH
  2. high Ca
  3. occurs after years of secondary hyperparathyroidism
    produce PTH even after the correction of Ca deficiency
27
Q

Clinical features of tertiary hyperparathyroidism?

A

Bones
Stones
Abdominal groans
Psychic moans

28
Q

Investigations of tertiary hyperparathyroidism?

A

Blood:

  • raised calcium
  • raised PTH
29
Q

Management of tertiary hyperparathyroidism?

A

Cinacalet: lowers serum calcium

Total or subtotal thyroidectomy

30
Q

What will happen to blood concentrations of ions after Parathyroidectomy?

A

Transient hypocalcaemia

31
Q

What is hypoparathyroidisim?

A

Low levels of PTH made by the parathyroid glands

Very rare, sometimes caused by neck surgery

32
Q

Blood test results you would see in hypoparathyrodism?

A

Hypocalcaemia
Hyperphosphataemia

Low or normal levels of PTH

33
Q

What is pseudohypoparathyroidism?

A

Hypocalcaemia
Hyperphosphataemia

BUT high levels of PTH

The problem is caused by resistance to PTH

34
Q

Clinical features of hypoparathyrodism?

A

Signs of low calcium and high phosphate

Increased excitability of nerves
Numbness around the mouth/extremities

Cramps, tetany, convulsions

35
Q

Management of hypoparathyrodism?

A

Acutely: raise serum calcium

Persistent: Alfacalcidiol

Endocrinology (19 decks)

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