Hypersecretion of anterior pituitary hormones Flashcards
What normally causes hyperpituitarism?
Isolated pituitary tumours or can be ectopic
What defect is hyperpituitarism usually associated with?
Visual field defects eg bitemporal hemianopia due to the descussation of the nerves being at the optic chiasm where the pituitary is
What does an excess of ACTH cause?
Cushing’s disease
What does an excess of TSH cause?
Thyrotoxicosis
What does an excess of LH/FSH cause?
Precocious puberty in children
What does an excess of prolactin cause?
Hyperprolactinaemia
What does an excess of GH cause?
Gigantism, acromegaly
What are physiological causes of hyperprolactinaemia?
Pregnancy and breastfeeding
What are pathological causes of hyperprolactinaemia?
Prolactinoma - a microadenoma of <10mm and the most common functioning pituitary tumour.
What does high prolactin supress
GnRH pulsality
What are signs of hyperprolactinaemia in women
Galactorrhoea, secondary amenorrhoea/oligomenorrhoea, loss of libido, infertility
What are signs of hyperprolactinaemia in men?
Galactorrhoea, erectile dysfunction, loss of libido, infertility
What is the pathophysiology of the treatment for hyperprolactinaemia?
Dopamine from dopaminergic neurones bind to D2 receptors on the lactotrophs and switches off prolactin secretion
What is the treatment for hyperprolactinaemia?
D2 receptor agonists that deliberately inhibit prolactin release - 1st line treatment
What do D2 receptor agonists do to hyperprolactinaemia?
Decrease prolactin secretion and reduce the tumour size
What are examples of D2 receptor agonists?
Bromocriptine, cabergoline
What is the difference between giganistim and acromegaly
Gigantism is in children and acromegaly is in adulthood
What are acromegaly and gigantism usually due to
Benign GH secreting pituitary adenomes
What are possible general complication risks of acromegaly and what are the chances of getting them?
CVS - 60%
Resp complications - 25%
Cancer - 15%
What are clinical features of acromegaly?
excessive sweating (hyperhidrosis), headache, supraorbital ridge enlargement, big nose, big hands and feet, thickened lips, macroglossia, prognathism (protrusion of lower jaw), carpal tunnel syndrome, barrel chest and kyphosis.
What grows in acromegaly?
Periosteal bone, cartilage, fibrous tissue, connective tissue, internal organs ie hepatomegaly
What are complications of acromegaly?
OSA - increased soft tissue growth in throat
Hypertension - effect of GH and/or IGF-1 on vascular tree, GH mediated Na reabsorption
Cardiomyopathy - hypertension, DM, toxic effects of GH on myocardium
Cancer - colonic polyps
What other hormone is often high in acromegaly apart from GH
Prolactin - reflects tumour secreting both GH and prolactin, and the hyperprolactinaemia will cause secondary hypogonadism
How can diabetes mellitus develop in someone with acromegaly?
Excess GH inhibits insulin, increases insulin resistance. This impaires glucose tolerance and causes diabetes mellitus
