hypersecretion of anterior pituitary hormones

Question 1

what is hyperpituitarism

Answer 1

Symptoms associated with excess production of adenohypophysial hormones

Question 2

what is hyperpituitarism usually due to?

Answer 2

Usually due to isolated pituitary tumours but can also be ectopic (i.e. from non-endocrine tissue) in origin

Question 3

what does excess of the following hormones lead to ? 
ACTH
TSH
LH/FSH
Prolactin 
GH

Answer 3

cushings 
thyrotoxicosis 
precocious puberty in children 
hyperprolactinaemia 
gigantism, acromegaly

Question 4

what is hyperprolactinaemia

Answer 4

too much prolacin

Question 5

what are the causes of hyperprolactinaemia

physiological and pathological

Answer 5

Physiological
pregnancy
breastfeeding
Pathological
prolactinoma (often microadenomas < 10mm diameter)
Prolactinoma = most common functioning pituitary tumour
High prolactin suppresses GnRH pulsatility

Question 6

what can hyperprolactinaemia due to pituitary adenoma cause in women?

Answer 6

galactorrhoea (milk production)
secondary amenorrhoea (or oligomenorrhoea)
loss of libido
infertility

Question 7

what can hyperprolactinaemia due to pituitary adenoma cause in men?

Answer 7

galactorrhoea uncommon (since appropriate steroid background usually inadequate)
loss of libido
erectile dysfunction
infertility

Question 8

where is prolactin released from

Answer 8

anterior pituitary lactotroph

Question 9

what does dopamine from hypothalamic dopaminergic neurons bind to and lead to?

Answer 9

dopamine binds to D2 receptors and blocks the release of prolactin

Question 10

what is the treatment for hyperprolactinaemia

-with examples

Answer 10

Medical treatment is 1st line 
Dopamine receptor (D2) agonists
Decrease prolactin secretion
Reduce tumour size
Examples:
BROMOCRIPTINE
CABERGOLINE
Oral administration

Question 11

what are the side effects of dopamine receptor agonists

Answer 11

Nausea and vomiting
Postural hypotension
Dyskinesias
Depression
 pathological gambling

Question 12

excess growth hormone in children and adulthood are called?

Answer 12

child = gigantism
adult = acromegaly

Question 13

what grows in acromegaly

Answer 13

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

Question 14

what are the clinical features of acromegaly

Answer 14

excessive sweating (hyperhidrosis)
headache
enlargement of supraorbital ridges, nose, hands and feet, thickening of lips and general coarseness of features
enlarged tongue (macroglossia)
mandible grows causing protrusion of lower jaw (prognathism)
carpal tunnel syndrome (median nerve compression)
barrel chest, kyphosis

Question 15

what are the metabolic effects of acromegaly

Answer 15

excess growth hormone
leads to increased endogenous glucose production, decreased muscle glucose uptake
leads to increased insulin production = increased insulin resistance
which then leads to impaired glucose tolerance
leading to diabetes mellitus

Question 16

what are the complication of acromegaly?

Answer 16

-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

Question 17

What is other hormone is co-secreted along with GH in acromegaly?

Answer 17

Prolactin is often high in acromegaly – may reflect tumour secreting GH AND prolactin
Hyperprolactinaemia will cause secondary hypogonadism (see clinical features of hyperprolactinaemia)

Question 18

diagnosis of acromegaly -what can you use?

Answer 18

GH pulsatile – so random measurement unhelpful
Elevated serum IGF-1 
Failed suppression (‘paradoxical rise’) of GH following oral glucose load – oral glucose tolerance test

Question 19

draw the graph to show the difference between normal and acromegalic response to glucose induced suppression of growth hormone secretion in acromegaly

Answer 19

acromegalic = increases
normal = decreases

acromegaly= paradoxical rise in GH

Question 20

what is the treatment of acromegaly?

Answer 20

Surgery (trans-sphenoidal) – 1ST LINE
Medical 
Somatostatin analogues
e.g. OCTREOTIDE
Dopamine agonists (GH secreting pituitary tumours frequently express D2 receptors)
e.g. CABERGOLINE
Radiotherapy

Question 21

what do somatostatin analogues do?

what are the side effects

Answer 21

‘Endocrine cyanide’
Injection: sc (short acting) or monthly depot
GI side effects common eg nausea, diarrhoea, gallstones can occur
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)