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The Endocrine System > Growth Hormone and Acromegaly > Flashcards

Growth Hormone and Acromegaly Flashcards

1
Q

Which hormone can inhibit release of growth hormone from the anterior pituitary?

A

Somatostatin

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2
Q

What impact does growth hormone have on the liver?

A
  1. Increases liver gluconeogenesis
  2. Insulin growth factors (IGF-1) are released
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3
Q

How is glucose uptake affected by growth hormone

a) In the brain
b) In muscle cells

A

a) Increased
b) Decreased

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4
Q

Growth hormone has an impact on lipolysis

True or false?

A

True

It increases it allowing for more free energy sources in the body

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5
Q

IGF-1 is responsible for which two types of growth?

A
  1. Soft tissue
  2. Bone
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6
Q

What are the main anabolic effects of growth hormone on the body?

A
  1. Increases free glucose and fatty acids
  2. Increases protein synthesis
  3. Decreases fat storage
  4. Increases soft tissue growth (IGF-1)
  5. Increases bone growth (IGF-1)
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7
Q

Which physical changes can excess growth hormone have on the body?

A
  1. Prominent brow
  2. Large nose and jaw
  3. Pronounced cheek bones
  4. Skin changes
  5. Oral manifestations (difficulty eating/swallowing/dental pain/interdental separation)
  6. Large hands
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8
Q

How does excess growth hormone affect the hands and feet?

A
  1. Increase in size
  2. Spade-like hands

(it is a good idea to ask about shoes size changes)

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9
Q

How does excess growth hormone affect the skin?

A
  1. Thicker
  2. Excessive sweating
  3. Acne
  4. Greasier skin
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10
Q

How does excess growth hormone affect the face?

A
  1. Prominent supraorbital ridge (brow)
  2. Increased size and pronouncement of jaw (prognathism)
  3. Coarsening of facial features
  4. Enlarged tongue
  5. Tissue swelling in larynx
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11
Q

How does excess growth hormone affect the dentition?

A
  1. Interdental separation (mandible increases in size)
  2. Damage to teeth (due to overbite wear and tear)
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12
Q

How does excess growth hormone affect behaviour?

A
  1. Polyuria
  2. Polydipsia
  3. Lethargic (lack of sleep)
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13
Q

How does excess growth hormone affect sleep patterns?

A
  1. Causes obstructive sleep apnoea (tongue and larynx increase in size, snoring)
  2. Increased tissue growth in larynx can deepen /coarsen the voice
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14
Q

Which other conditions may occur as a complication of growth hormone excess?

A
  1. Diabetes (T2DM)
  2. Hypertension
  3. Carpal tunnel syndrome
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15
Q

Why can diabetes occur as a complication of growth hormone excess?

A
  1. Chronically raised plasma glucose
  2. Insulin sensitivity reduces
  3. Classic symptoms follow (polyuria, polydipsia, glucosuria, lethargy)
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16
Q

Why does hypertension occur as a complication of growth hormone excess?

A
  1. Increases lipolysis of fats occurs
  2. Increases fatty plaque production in arteries
  3. Hypertension follows
17
Q

Why do people with growth hormone excess suffer from oily skin?

A
  1. Increase in lipolysis
  2. Plasma free fatty acids increase
  3. Oily skin develops as a result
18
Q

Why does carpal tunnel syndrome occur as a complication of growth hormone excess?

A
  1. Increased growth of soft tissues in hands and forearms
  2. Compression of median nerve
19
Q

Which hormones are produced by the hypothalamus that can have an impact on the production of growth hormone by the anterior pituitary?

A
  1. Growth hormone releasing hormone (GHRH)
  2. Somatostatin
20
Q

What impact does IGF-1 have on

a) Anterior pituitary
b) Hypothalamus

A

a) Inhibits growth hormone production
b) Stimulates somatostatin production

21
Q

What is the most likely cause for growth hormone hypersecretion?

A

Pituitary tumour

(may be ectopic carcinoid tumour, yet this is rarer)

22
Q

Which two type of pituitary tumour can cause growth hormone hypersecretion?

A
  1. Microadenoma (<1cm)
  2. Macroadenoma (>1cm)
23
Q

Why does giantism occur?

A

Excess IGF-1 acts on epiphyseal growth plates which have not yet fused causing growth

24
Q

What may be the main complications of a pituitary macroadenoma versus a microadenoma?

A
  1. Headaches (due to compression)
  2. Compression of optic chiasm causing bitemporal hemianopia
  3. 1/3rd of cases are associated with hypersecretion of prolactin
  4. Compression can suppress other hormone production causing hypopituitarism
25
Q

Why do growth hormone levels vary greatly throughout the day?

A

GHRH is released in a pulsatile manner

26
Q

At which time in life does growth hormone usually peak?

A

Puberty

27
Q

GH levels are _____ in pregnancy

A

GH levels are low in pregnancy

28
Q

What is the definitive test for GH excess?

A

OGTT

29
Q

Why does an OGTT work for determining growth hormone excess?

A

Normally high glucose levels inhibit growth hormone production

Failure to drop to undetectable levels shows there is autonomous secretion of GH

30
Q

Describe the steps for an OGTT for GH excess

A
  1. Fast overnight
  2. At 9am take 300ml fluid with 75g of sugar
  3. Record plasma glucose levelsevery 30mins for 2 hours
31
Q

What are the cut off values in an OGTT for excess growth hormone?

A
  1. No acromegaly GH is suppressed to <1mcg/L
  2. Acromegaly GH remains >1mcg/L
32
Q

Levels of IGF-1 reflect ____ levels of GH

A

Levels of IGF-1 reflect 24hr levels of GH

33
Q

Why are pituitary function tests essential in a patient with suspected acromegaly?

A

To determine if there is associated hypopituitarism

34
Q

What are the treatment options for a pituitary tumour?

A
  1. Trans-sphenoidal surgery
  2. Radiotherapy
  3. Dopamine agonists
  4. Somatostatin receptor agonists
  5. Growth hormone antagonists
35
Q

What are the downsides to using radiotherapy for a pituitary tumour?

A
  1. It may take a long time (10 years) to have an effect
  2. It may induce hypopituitarism
36
Q

Which specific dopamine agonists can be used to treat acromegaly and what are their key benefits?

A

Bromocriptine, cabergoline

  1. Useful if the tumour also secretes prolactin
  2. Can reduce tumour size
  3. Prolactin release suppressed
37
Q

Which specific somatostatin receptor agonists can be used to treat acromegaly and what are their key benefits?

A

Octreotide, Lanreotide

  1. Somatostatin analogues suppress GH release
  2. Can act quickly
38
Q

Which specific growth hormone receptor antagonist can be used to treat acromegaly and what are the key benefits?

A

Pegvisomant

  1. Acts on GH receptors in cells in the body
  2. Can normalise IGF-1 levels

The Endocrine System (35 decks)

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