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Y2 LCRS1 Endocrinology > Hypersecretion of Anterior Pituitary Hormones > Flashcards

Hypersecretion of Anterior Pituitary Hormones Flashcards

1
Q

What is the usual cause of hypersecretion of anterior pituitary hormones?

A

Pituitary adenoma but can be ectopic (i.e. from non-endocrine tissue)

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2
Q

What visual defect is associated with pituitary adenoma?

A

Bitemporal hemianopia

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3
Q

What is the cause of bilateral hemianopia? How is it assessed?

A
  • At the optic chiasm, fibres from the nasal retinae cross.
  • Light from outer (temporal) aspects of visual field strikes the nasal aspect of the retina
  • Compression of these crossing fibres at the optic chiasm means that there is loss of vision from the outer temporal visual fields.

Assessment: Diagram below is constructed from a visual fields test. Every time the patient sees a flash they have to press a button. Shows a loss of temporal field.

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4
Q

State the disease resulting from hypersecretion of:

  • a. Corticotrophin
  • b. Thyrotrophin
  • c. Gonadotrophin
  • d. Prolactin
  • e. Somatotrophin
A

a. Cortictrophin - Cushing’s disease
b. Thyrotrophin - Thyrotoxicosis
c. Gonadotrophins - Precocious puberty in children
d. Prolactin - Hyperprolactinaemia
e. Somatotrophin - Gigantism/Acromegaly

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5
Q

State two physiological causes of hyperprolactinaemia.

A

Pregnancy

Breast feeding

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6
Q

What is the usual pathological cause of hyperprolactinaemia?

A

Prolactinoma (most commonly microadenomas (< 10 mm)) = most common functioning pituitary tumrour.

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7
Q

What is the effect of high prolactin on GnRH?

A

GnRH pusatility is suppressed by high prolactin

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8
Q

State the symptoms of hyperprolactinaemia in men and women.

A
  • Loss of libido (in both)
  • Infertility (in both)
  • Galactorrhoea (rarely occurs in males since appropriate steroid background usually inadequate)
  • Oligomenorrhoea/amenorrhoea (in women)
  • Impotence (in men)
  • Erectile dysfunction (in men)
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9
Q

How is prolactin secretion regulated? How can we expolid this pharamceutically?

A
  • Release of prolactin from anterior pituitary lactotrophs can be regulated by dopamine
  • Dopamine from hypothalamic dopaminergic neurons binds to D2 receptors on the lactotrophs
  • This stops the release of prolactin

D2 receptor agonsists can be used in hyperprolactinaemia to:

  • decrease prolactin secretion
  • reduce tumour size
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10
Q

What is used to treat hyperprolactinaemia? What is the ROA?

A

Dopamine (D2) agonists – bromocriptine and cabergoline

ROA: oral administration

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11
Q

Describe the side-effects of dopamine receptor agonists.

A
  • Nausea/vomiting
  • Postural hypotension
  • Dyskinesias
  • Depression - must tell patients about this as it could otherwise result in a lawsuit
  • Pathological gambling - doctors ask patients to tell a friend to inform their doctor of any strange behaviour
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12
Q

What does excess growth hormone cause in children and in adults? What is the USUAL cause?

A

Children – gigantism

Adults – acromegaly

CAUSE: benign growth hormone secreting pituitary adenoma

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13
Q

What are the most common causes of death in excess GH?

A

Excess GH –> increased morbidity and mortality:

  • Cardiovascular problems (60%)
  • Respiratory problems (25%)
  • Cancer (15%)
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14
Q

What grows in acromegaly?

A
  • periosteal bone
  • cartilage
  • fibrous tissue
  • connective tissue
  • internal organs (cardiomegaly, splenomegaly, hepatomegaly, etc.)
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15
Q

State some common clinical features of acromegaly.

A
  • Hyperhydrosis - excessive sweating
  • Headache
  • Enlargement of supraorbital ridges, nose, hands and feet, thickening of lips and general coarseness of features
  • Macroglossia - enlarged tongue
  • Proganthism - mandible grows causing protrusion of lower jaw
  • Carpal tunnel syndrome - due to median nerve compression
  • Barrel chest, kyphosis
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16
Q

Describe the onset of acromegaly.

A

Insidious in onset - signs and symptoms progress gradually. Patients can bring old photos to help diagnose.

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17
Q

What are the metabolic effects of acromegaly?

A

Excess GH –>

Increased endogenous glucose production, decreased muscle glucose uptake –>

increased insulin production=increased insulin resistance –>

impaired glucose tolerance –> diabetes mellitus (in 10%)

18
Q

What are the complications in acromegaly?

A

Obstructive sleep apnoea - Bone and soft-tissue changes surrounding the upper airway lead to narrowing and subsequent collapse during sleep

Hypertension - Direct effects of GH &/or IGF-1 on vascular tree; GH mediated renal sodium reabsorption

Cardiomyopathy - Hypertension, DM, direct toxic effects of excess GH on myocardium

Increased risk of cancer - Colonic polyps, regular screening with colonoscopy

19
Q

What type of cancer is more common in acromegaly?

What systemic disease are people with acromegaly likely to have?

A

Colonic cancer - polyps

Hypertension

20
Q

What type of test is used to diagnose a hyperpituitary disorder?

A

Suppression test

21
Q

What test is used to diagnose acromegaly and how are the results interpreted?

A

Glucose-induced suppression of growth hormone secretion

  • Giving glucose should cause a decrease in growth hormone release in a normal individual
  • In someone with acromegaly, giving glucose will cause a paradoxical rise in growth hormone release

Serum IGF-1 - elevated

Serum GH - unhelpful because pulsatile

22
Q

Apart from GH, what would be elevated in the serum in acromegaly?

A

IGF-1

23
Q

What is the FIRST line treatment of acomegaly?

A

Trans-sphenoidal surgey

24
Q

State some of the treatments for acromegaly.

A

Transsphenoidal hypophysectomy

Radiotherapy

Chemotherapy:

  • Octreotide (somatostatin analogue)
  • Cabergoline (dopamine receptor agonists)
25
Q

What other hormone is often high in acromegaly? What does this show?

A

Prolactin - often high in acromegaly; may reflect the tumour secreting GH and prolactin.

26
Q

What are the secondary effects of hyperprolactinaemia?

A

Hyperprolactinaemia will cause secondary hypogonadism (NB: prolactin is co-secreted with GH in acromegaly)

27
Q

Why are dopamine antagonists useful in the treatment of acromegaly?

A

GH secreting pituitary tumours frequently express D2 receptors

28
Q

Name a somatostatin analogue used in the treatment of acromegaly. What are they sometimes called?

A

Octreotide

“Endocrine cyanide”

29
Q

What are the clinical uses of somatostatin analogues e.g. octreotide?

A
  • Reduces GH secretion and tumour size
  • Pre-treatment before surgery may make resection easier
  • Use post-operatively if not cured or whilst waiting for radiotherapy to take effect (slow)
30
Q

Describe the administration and DOA of somatostatin analogues.

A

Administered by injection SC (short acting) or monthly depot

31
Q

State some of the side effects of somatostatin analogues.

A

GI side effect are common (because somatostatin is produced by the small intestine as well) e.g.

  • Nausea
  • Diarrhoea
  • Rarely gallstones (due to less CCK)
32
Q

Summarise briefly the regulation of GH secretion.

A

GHRH –> GH –> liver –> somatomedin production e.g. IGF-1

SS = somatostatin aka growth hormone inhibiting hormone

33
Q

Polypeptide/protein hormones…?

a) include growth hormone
b) are well absorbed when given orally
c) normally have a duration of action of more than 24h
d) show no species variation
e) act on membrane-bound receptors

A

Polypeptide/protein hormones: include growth hormone = True

are well absorbed when given orally = False

normally have a duration of action of more than 24h = False

show no species variation = False

act on membrane-bound receptors = True

34
Q

A tumour in the pituitary:

a) most commonly presents with thyroid hormone deficiency
b) can be associated with the loss of peripheral vision (bitemporal hemianopia)
c) is usually a microadenoma
d) may be associated with the symptoms of diabetes mellitus
e) is often a cause of hypertension

A
  • A tumour in the pituitary: most commonly presents with thyroid hormone deficiency = False
  • can be associated with the loss of peripheral vision (bitemporal hemianopia) = True
  • is usually a microadenoma = True
  • may be associated with the symptoms of diabetes mellitus = True
  • is often a cause of hypertension = False
35
Q

Panhypopituitarism:

a. is a condition which develops following a prolonged raised circulating cortisol concentration
b. is usually caused by a hypothalamic tumour
c. can be a consequence of post-partum haemorrhage
d. is treated with replacement hypothalamic releasing hormone therapy
e. is naturally associated with the aging process

A
  • Panhypopituitarism: is a condition which develops following a prolonged raised circulating cortisol concentration = False
  • is usually caused by a hypothalamic tumour = False
  • can be a consequence of post-partum haemorrhage = True
  • is treated with replacement hypothalamic releasing hormone therapy =False
  • is naturally associated with the aging process = False
36
Q

The lack of circulating growth hormone (somatotrophin):

a. in children is a cause of short stature
b. can result in symptoms associated with diabetes mellitus
c. is associated with raised circulating IGF levels
d. generally requires replacement therapy in adults
e. can be successfully treated with a somatostatin agonist

A
  • The lack of circulating growth hormone (somatotrophin): in children is a cause of short stature =True
  • can result in symptoms associated with diabetes mellitus =False
  • is associated with raised circulating IGF levels = False
  • generally requires replacement therapy in adults =False
  • can be successfully treated with a somatostatin agonist =False
37
Q

Prolactinomas:

a. are described as macroadenomas if they are less than 1 cm in diameter
b. may cause infertility
c. may cause galactorrhoea in men
d. are sometimes diagnosed following initial presentation with visual defects
e. can be treated with cabergoline

A
  • Prolactinomas: are described as macroadenomas if they are less than 1 cm in diameter = False
  • may cause infertility = True
  • may cause galactorrhoea in men =True
  • are sometimes diagnosed following initial presentation with visual defects =True
  • can be treated with cabergoline = True
38
Q

Excess production of growth hormone (somatotrophin) in adults:

  1. is usually associated with a pituitary tumour
  2. can be diagnosed using an oral glucose tolerance test
  3. is often indicated by an increase in linear growth
  4. can be the cause of hypoglycaemic episodes
  5. can be treated with a somatostatin analogue
A
  • Excess production of growth hormone (somatotrophin) in adults: is usually associated with a pituitary tumour = True
  • can be diagnosed using an oral glucose tolerance test = True
  • is often indicated by an increase in linear growth = False
  • can be the cause of hypoglycaemic episodes =False
  • can be treated with a somatostatin analogue = True
39
Q

Dopamine receptor agonists:

a. are the drugs of choice in the treatment of acromegaly
b. inhibit prolactin secretion
c. are normally polypeptides
d. induce nausea
e. cause Parkinson-like movement disorders

A
  • Dopamine receptor agonists: are the drugs of choice in the treatment of acromegaly = False
  • inhibit prolactin secretion = True
  • are normally polypeptides =False
  • induce nausea = True
  • cause Parkinson-like movement disorders = False
40
Q

Irregular periods, galactorrhoea, very high prolactin =?

A

Small tumour producing prolactin

41
Q

What is the difference between prolactinoma and non functioning adenoma?

A

Dopamine supresses prolactin

Pituitary tumours = harmless, very common….

Y2 LCRS1 Endocrinology (18 decks)

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