Hypersecretion of Anterior Pituitary Hormones Flashcards
Most common reason for hyperpituitarism?
Usually due to isolated tumours in the pituitary.
If not due to a pituitary tumour, what is the other common reason for hyperpituitarism, give an example?
Ectopic production of hormones from tumours, vasopressin producing lung tumours
What defect is hyper pituitarism from pituitary tumour associated with and why
Visual field defects and the tumour can grow up and squash the optic chiasm
What Visual field defect can a pituitary tumour cause
Bilateral hemianopia
How does a ptuitary tumour cause Bilateral hemianopia
At the optic chiasm, the fibres from the inner (nasal) part of both retinae (corresponding to the outer visual field) cross.
Light from the left visual field will hit the right part of the retina and vice versa
Because of the crossing over, all the light from the left visual field is detected by the right side of the brain.
A pituitary tumour could protrude out of the sella turcica and disrupt the fibres coming from the nasal parts of the retinae by compressing the optic chiasm where the optic nerves cross.
What is bilateral hemianopia
loss of the temporal/outer part of the visual field.
loss of the temporal/outer part of the visual field is known as….
bilateral hemianopia
What disease is excess corticotrophin by a pituitary tumour known as …
Cushings disease
Cushings disease is caused by …
excess corticotrophin (ACTH) by a pituitary adenoma
What disease is excess ACTH by a pituitary tumour known as …
Cushings disease
What is excess ACTH known as …
Cushings syndrome
What is Cushings syndrome
Excess ACTH in the blood
What does excess thyrotrophin result in …
thyroxicosis
What does excess gonadotrophins result in … (2)
Precocious puberty in children and a large ovary in women
Precocious puberty in children is caused by …
Gonadotrophins
What does excess prolactin result in …
Hyperprolactinaemia
What does excess somatotrophins result in … (2)
Gigantism in children, acromegaly in adults
Gigantism is caused by ….
Excess somatotrophin
Acromegaly is caused by…
Excess somatotrophin
a large ovary in women is caused by ….
excess oestrogen through excess gonadotrophins
Hyperprolactinaemia is defined as… (think about physiological hyperprolactinaemia)
Excess circulating prolactin when not due to a physiological cause such as pregnancy or breast-feeding
How serious is hypoprolactinaemia
HYPOprolactinaemia isn’t really a problem because the absence of prolactin doesn’t really have any serious physiological consequences
Most common type of prolactinoma?
Microadenoma, (a prolactinoma)
Symptoms of hyperprolactinaemia due to Prolactinoma in women? (4)
Galactorrhoea
Secondary amenorrhoea (or oligomenorrhoea)
Loss of libido
Infertility
Symptoms of hyperprolactinaemia due to Prolactinoma in men? (4)
Galactorrhoea uncommon
Importence
Loss of libido
Infertility
What effect does High levels of prolactin have on the reproductive axis
High prolactin suppresses GnRH pulsatility from the hypothalamus.
and so It decreases LH and FSH
How does High levels of prolactin cause secondary amenorrhoea
High prolactin suppresses GnRH pulsatility from the hypothalamus.
and so It decreases LH and FSH leading to secondary amenorrhea
why is Galactorrhoea in men very uncommon
Uncommon as you need oestrogen to prime the breast but men don’t have much oestrogen circulating in their bodies.
How does hyperprolactinaemia cause loss of libido, impotence and infertility
High prolactin suppresses GnRH pulsatility from the hypothalamus.
and so It decreases LH and FSH leading to loss of libido, impotence and infertility
What receptor is on lactotrophs
D2
What hormone regulates prolactin secretion
Dopamine
How does dopamine regulate prolactin secretion
Dopamine binds to D2 receptors on lactotrophs and inhibits prolactin secretion, and a lower level of dopamine means that the inhibition is lifted allowing the secretion of prolactin
What is different for first line treatment of hyperprolactinaemia compared to other tumours
MEDICAL TREATMENT IS FIRST LINE. ALL OTHER TUMOURS ARE USUALLY TREATED SURGICALLY FIRST.
What is used to treat hyperprolactinaemia
Dopamine receptor (D2) agonists are used. This decreases prolactin secretion and reduces tumour size.
Dopamine receptor (D2) agonists are used to treat what hyperpituitary condition
hyperprolactinaemia
and
Acromegaly
What hyperpituitary condition is bromocriptine used for
hyperprolactinaemia
What hyperpituitary condition is cabergoline used for
hyperprolactinaemia
and
Acromegaly
What drugs are used to treat hyperprolactinaemia (name)
bromocriptine and cabergoline
Which drug is first line for hyperprolactinaemia
Cabergoline
Side effects of D2 receptor agonists? (6)
nausea and vomiting, postural hypotension, dyskinesias and depression and pathological gambling
What weird ting do D2 receptor agonists cause
pathological gambling
In what case does hyperprolactinaemia call for a surgery
If there is a large prolactinoma, e.g. one compressing the optic chiasm, then a neurosurgeon is involved straightaway
Excess Somatotrophin In CHILDREN causes …
GIGANTISM
Excess Somatotrophin In adults causes …
Acromegaly
Acromegaly is caused by …
Excess Somatotrophin In adults
Gigantism is caused by …
Excess Somatotrophin In CHILDREN
Onset of acromegaly is described as …
Insidious - signs and symptoms progress very gradually over many years meaning it can go undiagnosed for a while.
If untreated, acromegaly (and gigantism) are associated with what morbidities (3)
increased morbidity and mortality due to cardiovascular (60%), respiratory (25%) and cancerous (15%) complications
What grows in acromegaly (5)
Periosteal bone Cartilage Fibrous tissue Connective tissue Internal organs (cardiomegaly, splenomegaly, hepatomegaly etc.)
What causes the increased demand in the CVS system
increase in organ size
This means that there is increased demand for oxygen and the blood supply must keep up with this extra demand
What are the manifestations of acromegaly? (MANY)
Enlargement of supraorbital ridges
Enlargement of nose, hands and feet
Thickening of lips
General coarseness of features
Hyperhydrosis
Headache
Mandible grows leading to protrusion of the lower jaw (prognathism)
Enlarged tongue – macroglossia.
Carpal Tunnel Syndrome (median nerve compression)
increased cartilaginous growth increasing the pressure on nerves
Spade shaped hands.
Joint pain
Barrel chest, kyphosis
Galactorrhoea (often in women and occasionally in men) -‐ at very high levels, GH has some prolactin like effects
Menstrual abnormalities, decreased libido and impotence
Hypertension -‐ there is a massive strain on the CVS and this is associated with an increase in blood pressure as the body tries to supply blood to the extra tissues
Abnormal glucose tolerance; symptoms of diabetes mellitus
Prognathism
What disease does acromegaly predispose
Diabetes
How does acromegaly predispose to diabetes
excess GH stimulates an increase in blood glucose (through increased endogenous glucose production and decrease muscle glucose uptake). This increase stimulates insulin production which then leads to tissue resistance to insulin
What effect does GH have on blood glucose and how
increase in blood glucose (through increased endogenous glucose production and decrease muscle glucose uptake).
Complications of Acromegaly? (4)
Obstructive sleep apnoea
Hypertension
Cardiomyopathy
Increased cancer risk
How does acromegaly cause Obstructive sleep apnoea
bone and soft-tissue changes surrounding the upper airway lead to narrowing and subsequent collapse during sleep
How does acromegaly cause Hypertension (2)
probs due to GH/IGF-1 effects on vascular tree and GH mediated renal sodium consumption.
How does acromegaly cause Cardiomyopathy (3)
hypertension, diabetes mellitus, direct toxic effects of excess GH on the myocardium
GH is often cosecreted with what
Prolactin
Hyperprolactinaemia will cause what other pituitary associated condition
Hypogonadism
Why is random measurement of GH unhelpful
GH release is pulasatile
What is used to diagnose high GH levels
oral glucose tolerance test
what is the oral glucose tolerance test results in acromegaly
Paradoxical rise in GH levels
what is the oral glucose tolerance test results in a normal person
you should inhibit growth hormone release and growth hormone levels will decrease and then you get an overswing at the end
GH affects on glucose
Increase serum glucose
What is the oral glucose tolerance test used to test
Acromegaly and growth hormone
the main treatment of acromegaly?
Surgery
What surgery is performed for GH
Trans-sphenoidal hypophysectomy
What medicine types are used to treat acromegaly (2)
Somatostatin analogues
Dopamine Agonists
How does dopamine agonists help with acromegaly?
GH secreting pituitary tumours often express D2 receptors
Examples of somatostatin analogues?
Octeotride
Octeotride is a…
somatostatin analogue
Octeotride is used to treat what pituitary condition
Acromegaly
Somatostatins are renowned as being …
endocrine cyanide
Somatostatins effect on GH secretion
Inhibitory
Serum levels of IGF in excess GH secretion?
high
3 treatment options for acromegaly?
Surgery - transphernoidal hypophysectomy
Medicine - somatostatin analogues/D2 agonists
Radiotherapy
Side effects of somatostatin analogues?
‘Endocrine cyanide’ – can interfere with gut functions to e.g. gall stones because CCK is switched off, nausea and diarrhoea.
Neoadjuvant/adjuvant for transphernoidal hypophysectomy?
Somatostatin analogues
