Pituitary Flashcards
What is acromegaly?
excess growth hormone
Causes of acromegaly?
secondary to a pituitary adenoma in over 95% of cases. A minority of cases are caused by ectopic GHRH or GH production by tumours e.g. pancreatic.
Symptoms of acromegaly?
coarse facial appearance, spade-like hands, increase in shoe size
large tongue, prognathism, interdental spaces
What causes excessive sweating and oily skin in acromegaly?
Sweat gland hypertrophy?
What are features of pituitary tumour?
hypopituitarism, headaches, bitemporal hemianopia
What is a common hormone imbalance with acromegaly?
raised prolactin in 1/3 of cases → galactorrhoea
Which genetic disorder is a ssoc with acromegaly?
6% of patients have MEN-1
Complications of acromegaly?
hypertension
diabetes (>10%)
cardiomyopathy
colorectal cancer
Growth hormone (GH) levels diagnostic of acromegaly
false
Acromegaly first line test?
Serum IGF-1 levels
Acromegaly diagnostic tx?
oral glucose tolerance test (OGTT) with serial GH measurements
The OGTT test is recommended to confirm the diagnosis if IGF-1 levels are raised.
suppression of GH to < 1 μg/L following documented hyperglycemia during an oral glucose load.
Acromegaly - what can be used to monitor disease?
Serum IGF-1 may also be used to monitor disease
Describe results of Oral glucose tolerance test in normal vs acromegaly?
in normal patients GH is suppressed to < 2 mu/L with hyperglycaemia
in acromegaly there is no suppression of GH
may also demonstrate impaired glucose tolerance which is associated with acromegaly
A pituitary MRI may demonstrate a pituitary tumour in acromegaly
true
first line mx acromegaly?
Trans-sphenoidal surgery is the first-line treatment for acromegaly in the majority of patients.
second line mx acromegaly?
If a pituitary tumour is inoperable or surgery unsuccessful then medication may be indicated
medications used in acromegaly?
somatostatin analogue
pegvisomant
dopamine agonists
Mechanism of somatostatin analogue
directly inhibits the release of growth hormone
Example of somatostatin analogue
octreotide
How effective is somatostatin analogue in acromegaly?
effective in 50-70% of patients
Mechanism of pegvisomant
GH receptor antagonist - prevents dimerization of the GH receptor
How effective is pegvisomant in acromegaly?
very effective - decreases IGF-1 levels in 90% of patients to normal
doesn’t reduce tumour volume therefore surgery still needed if mass effect
How is pegvisomant administered?
once daily s/c administration
Pegvisomant reduces tumour volume in acromegaly
false
doesn’t reduce tumour volume therefore surgery still needed if mass effect
Example of dopamine agonists?
for example bromocriptine, ropinirole, cabergoline, apomorphine
How effectuve are dopamine agonists in acromegaly?
effective only in a minority of patients
dopamine agonists are the first effective medical treatment for acromegaly, however now superseded by somatostatin analogues
true
When is external irradiation used in acromegaly?
External irradiation is sometimes used for older patients or following failed surgical/medical treatment
ergot-derived dopamine receptor agonists (bromocriptine, cabergoline, ) have been associated with
pulmonary, retroperitoneal and cardiac fibrosis
ESR, creatinine and chest x-ray should be obtained prior to treatment and patients should be closely monitored
Adverse side effects of dopamine receptor agonists?
nausea/vomiting
postural hypotension
hallucinations
daytime somnolence
What is Prolactinoma?
Prolactinomas are a type of pituitary adenoma, a benign tumour of the pituitary gland.
Prolactinoma can be classified according to:
size
hormonal status
Prolactinoma size classification
a microadenoma is <1cm and a macroadenoma is >1cm
Prolactinoma hormonal status?
a secretory/functioning adenoma produces and excess of a particular hormone and a non-secretory/functioning adenoma does not produce a hormone to excess
What is the commonest type of pituitary adenoma?
Prolactinoma
Features of excess prolactin
men: impotence, loss of libido, galactorrhoea
women: amenorrhoea, infertility, galactorrhoea, osteoporosis
Diagnosis of Prolactinoma?
MRI
Mx of Prolactinoma?
in the majority of cases, symptomatic patients are treated medically with dopamine agonists (e.g. cabergoline, bromocriptine) which inhibit the release of prolactin from the pituitary gland
surgery is performed for patients who cannot tolerate or fail to respond to medical therapy. A trans-sphenoidal approach is generally preferred unless there is a significant extra-pituitary extension
Prolactin is secreted by
anterior pituitary gland
which hormone acts as the primary prolactin releasing inhibitory factor
Dopamine
hence dopamine agonists such as bromocriptine may be used to control galactorrhoea.
Causes of raised prolactin
prolactinoma pregnancy oestrogens physiological: stress, exercise, sleep acromegaly: 1/3 of patients polycystic ovarian syndrome primary hypothyroidism
Why can hypothyroidism cause raised prolactin?
due to thyrotrophin releasing hormone (TRH) stimulating prolactin release
Drug causes of raised prolactin
metoclopramide, domperidone
phenothiazines
haloperidol
very rare: SSRIs, opioids
What is pituitary adenoma?
A pituitary adenoma is a benign tumour of the pituitary gland.
How common is pituitary adenoma?
They are common (10% of all people1) but in most cases will never be found (asymptomatic) or are found as an incidental finding. They account for around 10% of adult brain tumours
Pituitary adenomas can be classified according to:
size (a microadenoma is <1cm and a macroadenoma is >1cm) hormonal status (a secretory/functioning adenoma produces and excess of a particular hormone and a non-secretory/functioning adenoma does not produce a hormone to excess)
After prolactinomas what is common pituitary adenoma?
non-secreting adenomas are the next most common, then GH secreting and then ACTH secreting adenomas.
Pituitary adenomas typically cause symptoms by
excess of a hormone
depletion of a hormone(s) (due to compression of the normal functioning pituitary gland)
stretching of the dura within/around pituitary fossa (causing headaches)##
compression of the optic chiasm (causing a bitemporal hemianopia due to crossing nasal fibers)
pituitary adenomas, particularly microadenomas, can be an incidental finding on neuroimaging and therefore called a
pituitary incidentaloma’.
Investigation for pituitary adenoma
a pituitary blood profile (including: GH, prolactin, ACTH, FH, LSH and TFTs)
formal visual field testing
MRI brain with contrast
Differential diagnoses pituitary adenoma
pituitary hyperplasia craniopharyngioma meningioma brain metastases lymphoma hypophysitis vascular malformation (e.g. aneurysm)
Treatment of pituitary adenoma
hormonal therapy (e.g. bromocriptine is the first line treatment for prolactinomas)
surgery (e.g. transsphenoidal transnasal hypophysectomy) e.g. if progression in size
radiotherapy
MEN 1
Parathyroid (95%): hyperparathyroidism due to parathyroid hyperplasia
Pituitary (70%)
Pancreas (50%): e.g. insulinoma, gastrinoma (leading to recurrent peptic ulceration)
Also: adrenal and thyroid
MEN 2A
Medullary thyroid cancer (70%)
2 P’s
Parathyroid (60%)
Phaeochromocytoma
MEN 2B
Medullary thyroid cancer
1 P
Phaeochromocytoma
Marfanoid body habitus
Neuromas
Cause of Men1
MEN1 gene
MEN 1 presentation most cmmonly
Most common presentation = hypercalcaemia
Cause MEN 2
RET oncogene
HOW is MEN inherited
autosomal dominant
Drug causes of gynaecomastia - commonest drug
spironolactone
Drug causes of gynaecomastia
spironolactone (most common drug cause) cimetidine digoxin cannabis finasteride GnRH agonists e.g. goserelin, buserelin oestrogens, anabolic steroids
Very rare drug causes of gynaecomastia
tricyclics isoniazid calcium channel blockers heroin busulfan methyldopa
Causes of gynaecomastia
physiological: normal in puberty syndromes with androgen deficiency: Kallman's, Klinefelter's testicular failure: e.g. mumps liver disease testicular cancer e.g. seminoma secreting hCG ectopic tumour secretion hyperthyroidism haemodialysis drugs
