Hypersecretion of anterior pituitary hormones Flashcards
What is hyperpituitarism?
Excess production of adenohypophysial hormones
What is the most common cause of hyperpituitarism?
Isolated pituitary tumours
What other organ does it often lead to problems with?
Eyes- visual field defects
What is bitemporal hemianopia?
A pituitary tumour projects out of the sella turcica and interferes with the optic chiasm especially the fibres coming from the nasal parts of the retinae which leads to loss of the temporal part of the visual field
What is hyperpituitarism of corticotrophin known as?
Cushing’s
What is hyperprolactinaemia?
Excess circulating prolactin when not due to a physiological cause such as pregnancy and breast feeding
What is the most common type of prolactinoma?
Microadenoma
What is the effect of high prolactin levels on the reproductive axis?
Decreases LH and FSH leading to secondary amenorrhoea, galactorrhea, loss of libido and infertility
What is excess somatotrophin known as in children and adults?
Children= Gigantism Adults= Acromegaly
What is the difference between gigantism and acromegaly?
In adults (acromegaly), the growth plates of the long bones have already fused so there is no longer a possibility of an increase in height but you still get other effects
What is the onset of acromegaly like?
Insidious
If gigantism/acromegaly is untreated, what happens?
Increase in morbidity/mortality due to mainly cardiac and respiratory problems- organ growth=increased demand for oxygen- big struggle for CVS
In acromegaly, what is their increased growth of? (5)
Periosteal bone Cartilage Fibrous tissue Connective tissue Internal organs
What are common clinical manifestations of acromegaly? (13)
Enlargement of supraorbital ridges Enlargement of nose, hands and feet Thickening of lips General coarseness of features Hyperhydrosis Prognathism Carpal tunnel syndrome Joint pain Barrel chest Galactorrhea Menstrual abnormalities, decreased libido and impotence Hypertension Diabetes
What is carpal tunnel syndrome?
When your hands shake due to increased cartilaginous growth increasing the pressure on the nerves
How do you diagnose hyperpituitarism?
Suppression test
In a normal case, what should happen to GH if you give glucose?
Hypoglycaemia is used to stimulate GH release so glucose will inhibit GH release and GH levels will decrease with an eventual increase at the end
In acromegaly, what happens to GH if you give glucose?
There is a paradoxical increase in GH
What is the main treatment of acromegaly?
Surgery- transphenoidal hypophysectomy
What are the other treatments for acromegaly?
Radiotherapy
Chemotherapy
Somatostatin analogues e.g octreotide
Dopamine analogues e.g. bromocriptine and cabergoline
What is the problem with radiotherapy?
If you do it over a long time you will end up becoming hypopituitary
When is octreotide used?
Short term use before surgery (it can reduce the size of the tumour)
How is octreotide administered?
Subcutaneous or intramuscular
What are the side effects of octreotide?
GI tract disturbances
Initial reduction in insulin secretion
Gallstones (rarely)
How is prolactinaemia treated?
Dopamine receptor agonists
What is the effect of dopamine on prolactin?
It inhibits prolactin release
Give two examples of dopamine receptor agonists?
Bromocriptine and cabergoline
How does bromocriptine exist normally in the body?
Highly inactive- 93% is bound to plasma protein
What are the unwanted effects of bromocriptine?
Nausea/vomiting Dyskinesia Psychomotor excitation Postural hypotension Vasospasm in hands and toes
What else is bromocriptine used for?
Suppression of lactation
Cyclical benign breast tumours
Parkinsons
What are the differences between bromocriptine and cabergoline?
Cabergoline- longer half life and side effects less pronounced
