Hypersecretion of Anterior Pituitary Hormones Flashcards

1
Q

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

A

Pituitary adenoma

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2
Q

What visual defect is associated with pituitary adenoma?

A

Bitemporal hemianopia

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3
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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4
Q

What is the usual cause of hyperprolactinaemia?

A

Prolactinoma

Most commonly microadenomas (< 10 mm)

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5
Q

State the symptoms of hyperprolactinaemia.

A

Loss of libido
Infertility
Galactorrhoea (rarely occurs in males as well) Oligomenorrhoea/amenorrhoea Impotence (in men)

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6
Q

State two physiological causes of hyperprolactinaemia.

A

Pregnancy

Breast feeding

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7
Q

What does excess growth hormone cause in children and in adults?

A

Children – gigantism

Adults – acromegaly

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8
Q

What are the most serious complications of excess growth hormone?

A
Cardiovascular problems (majority) and respiratory problems  
This is mainly due to organ growth
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9
Q

State some common clinical manifestations of acromegaly.

A
Prognathism 
Enlarged supraorbital ridges  
Enlarged soft tissue  
Hyperhydrosis  
Carpal tunnel syndrome (due to excessive cartilaginous growth) 
General coarseness of features 
Hypertension
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10
Q

What are the metabolic effects of acromegaly?

A

Increased insulin response to oral glucose leading to insulin resistance
This causes impaired glucose tolerance (in 50%) and diabetes mellitus (in 10%

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11
Q

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

A

Suppression test

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12
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

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13
Q

State some of the treatments for acromegaly.

A
Transsphenoidal Hypophysectomy 
Radiotherapy 
Chemotherapy: 
 Octreotide (somatostatin analogue)
 Bromocriptine and Cabergoline (dopamine receptor agonists)
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14
Q

What are the clinical uses of octreotide?

A

It can be used short-term before surgery to shrink the size of the pituitary adenoma
It can be used long-term if it can’t be controlled by other means
It is used as a treatment for other neuroendocrine tumours e.g. carcinoid tumours

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15
Q

Describe the administration, distribution and metabolism of octreotide.

A

Octreotide is administered SC or IM 3/day
It is retained in extracellular fluid
Half-life = 2-4 hours

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16
Q

State some of the side effects of octreotide.

A

GI tract disturbance (because somatostatin is produced by the small intestine as well)
Initial reduction in insulin secretion causing hyperglycaemia (octreotide inhibits the production of insulin by the beta cells)
Rarely gallstones

17
Q

What is used to treat hyperprolactinaemia?

A

Dopamine agonists – bromocriptine and cabergoline

18
Q

Describe the pharmacokinetics and side-effects of bromocriptine.

A
Administered orally 1/day 
Heavily plasma protein bound  
Half-life = 7 hours (hepatic metabolism) 
Side effects: 
 Nausea/vomiting/abdominal cramps 
 Dyskinesias
 Psychomotor excitation 
 Postural hypotension 
 Vasospasm in fingers and toes
19
Q

State some other uses of bromocriptine.

A

Suppression of lactation
Cyclical benign breast tumours (and cyclic breast pain)
Also used in acromegaly but doesn’t have the same beneficial effect on tumour size
Parkinson’s disease

20
Q

Describe the pharmacokinetics and side-effects of cabergoline.

A

Taken orally 1-2/week
Half-life = > 45 hours
Side effect: same as bromocriptine but less pronounced