The Pituitary Gland Clinical Case & Discussion Flashcards
Does the pituitary release just one hormone?
no many
Primary – ________ _____ affected
Secondary – ________
Tertiary – ___________
Primary – endocrine organ affected
Secondary – pituitary
Tertiary – hypothalamus
how is the release of hormones stopped?
through negative feedback
if there is too many hormones then this will stop more hormones being released
what are the 3 different types of pituitary diseases?
hypersecretion (tumours)
hypoecretion (mostly tumours, other causes)
space occupying
what hormones may be released in hypersecretion of pituitary gland and what is that disease called?
GH - acromegaly (gigantism)
ACTH - Cushing’s disease
Prolactin - hyperprolactinaemia
Hyposecretion form the pituitary will cause less of what hormones to be released?
Anterior (FSH/LH, GH, ACTH, TSH)
Posterior (vasopressin)
what can space occupying pituitary disease lead to?
optic chiasmal compression
What is acromegaly?
Acromegaly is a hormonal disorder that results from too much growth hormone (GH) in the body
In acromegaly, the pituitary produces excessive amounts of GH
Usually the excess GH comes from benign, or noncancerous, tumors on the pituitary
What are the clinical features of acromegaly?
Soft tissue overgrowth
- ‘spade like’ hands (rings)
- wide feet (shoes)
- coarse facial features
- thick lips & tongue
- carpal tunnel syndrome
- sweating
what are some complications of acromegaly?
- headache
- chiasmal compression
- diabetes mellitus
- hypertension
- cardiomyopathy
- sleep apnoea
- accelerated OA (osteoarthritis)
- colonic polyps & CA
How do you diagnosis of Acromegaly?
Can GH be suppressed? Give them glucose and this suppresses GH and if it doesn’t then think of acromegaly
is Insulin-like Growth Factor-1 (IGF-1) elevated?
Is the rest of pituitary function normal?
Is there a pituitary tumour on MRI?
Is vision normal?
Diagnosing acromegaly involves 2 key blood tests: a test to check the level of the insulin-like growth factor-1 (IGF-1) and an oral glucose tolerance test (OGTT)
Testing Insulin-like Growth Factor-1 (IGF-1):
GH tells the body to make IGF-1, which in turn causes tissues in your body to grow. In someone without acromegaly, a high IGF-1 level is the body’s signal to stop producing GH. For a person with acromegaly, though, the body continues producing GH, regardless of high IGF-1 levels. IGF-1 levels are much more constant throughout the day than GH levels, so doctors measure IGF-1 levels using a blood test. An elevated IGF-1 level may indicate acromegaly.
Oral Glucose Tolerance Test (OGTT):
Growth hormone levels and blood glucose levels are also connected. In someone without acromegaly, a higher blood glucose level usually causes the body to stop producing GH. Therefore, a doctor will purposely raise your blood glucose level using an OGTT and watch how your GH level responds.
If your GH level doesn’t drop to below 1 ng/mL (ng/mL is the standard measurement used for GH levels) during the OGTT, you have acromegaly. Your GH level should respond to so much glucose by dropping, so if it doesn’t, that tells the doctor that your body isn’t listening to its own signals: The delicate feedback loop of the endocrine system has been disturbed
what is cushing syndrome an excess of?
excess corticosteroids
Cushing’s syndrome is the collection of signs and symptoms due to prolonged exposure to glucocorticoids such as cortisol
is cortisol an aanabolic or catabolic hormone?
catabolic
Cortisol is a catabolic hormone which causes what?
Tissue breakdown - causes weakness of skin, muscle & bone
Sodium retention - may cause hypertension & heart failure
Insulin antagonism - may cause diabetes mellitus
what are high value symptoms and signs of cushings syndrome?
- skin atrophy
- spontaneous purpura
- proximal myopathy
- osteoporosis
- growth arrest in children
what are intermediate symptoms and signs of cushings syndrome?
- pink striae
- facial mooning & hirsutism
- oedema
what are non-specific signs and symptoms of cushings syndrome?
- central obesity
- hypertension
are all cases of cushings syndrome due to a pituitary tumour?
no
in cushing syndrome, what are the 2 different types?
ACTH-dependent and ACTH-independent
What is ACTH-dependent cushings syndrome
Pituitary tumour (Cushing’s disease)
Ectopic ACTH secretion (eg lung carcinoid)
What is ACTH-independent cushings syndrome?
Adrenal tumour (adenoma or carcinoma)
Corticosteroid therapy (eg for asthma, IBD)
what are some clinical manifestations of hyperprolactinaemia?
Galactorrhea is a milky nipple discharge unrelated to the normal milk production of breast-feeding
what are the causes and pathologies of hyperprolactinaemia?
Physiological - Pregnancy, lactation, stress
Pharmacological - DA depleting and DA antagonist drugs
Pathological - Primary hypothyroidism, Pituitary lesions (prolactinoma or pituitary ‘stalk pressure’)
prolactin is controlled by what?
dopamine
What are drugs which may cause hyperprolactinaemia?
Dopamine antagonists - neuroleptics (eg chlorpromazine), anti-emetics (eg metoclopramide)
DA-depleting agents
Oestrogens (not in OCP dosage)
Some antidepressants
* Don’t forget to ask about homeopathic or herbal remedies!
Clinical features of hypopituitarism in adults?
Tiredness, weight gain, depression, reduced libido, impotence, menstrual problems
Skin pallor
Reduced body hair
what are the clinical features of hypopitutarism in children?
Reduced linear growth
Delayed puberty
What is Cranial Diabetes Insipidus?
Cranial diabetes insipidus is a condition in which the hypothalamus does not produce enough anti-diuretic hormone
Cranial Diabetes Insipidus: differential diagnosis?
- Idiopathic (autoimmune hypophysitis?)
- Post-trauma (including pituitary surgery)
- Metastatic carcinoma
- Craniopharyngioma
- Other brain tumours: eg. germinoma
- Rare causes: eg. sarcoidosis
space occupation in the pituitary region normally goes what direction?
up but can go sideways
How does a space occupying lesion in the pituitary area affect vision?
Bitemporal hemianopia
Loss of side field vision
Compresses nasal fibres
Management of pituitary tumours causing hypersecretion?
dopamine agonists (prolactinoma)
somatostatin analogues (acromegaly)
GH receptor antagonist (acromegaly)
What does somatostatin inhibit?
Somatostatin from the hypothalamus inhibits the pituitary gland’s secretion of growth hormone and thyroid stimulating hormone. In addition, somatostatin is produced in the pancreas and inhibits the secretion of other pancreatic hormones such as insulin and glucagon
Management of pituitary tumours causing hyporsecretion (of the normal pituitary)?
cortisol, T4, sex steroids, GH
desmopressin
Management of pituitary tumours?
surgery (mostly transsphenoidal)
radiotherapy
how is pituitary surgery normall done?
through the nose
What are the beneficial effects of somatostatin analogues in acromegaly?
Improve soft tissue overgrowth, sweating, headache, sleep apnoea in most patients
Normalise GH and IGF-1 levels in over 50% patients
Induce tumour shrinkage in the majority
Reduce morbidity & mortality from acromegaly
(pictures show the somatostatin analogues used)
What are some adverse effects of
somatostatin analogues?
Nausea, cramps, diarrhoea, flatulence (often transient)
Cholesterol gallstones occur in 20-30% (mostly asymptomatic)
Slow-release preparations require monthly IM/SC injections
High cost (£6-12,000 annually)
What is a Microprolactinoma?
a benign tumor (adenoma) of the pituitary gland that produces a hormone called prolactin
it is the most common type of functioning pituitary tumor
<10mm
Most shrink
What is the treatment of Microprolactinoma?
Treatment with dopamine agonists
What does Microprolactinoma cause?
Usually women with galactorrhoea, amenorrhoea, infertility & serum PRL <5000 mU/l (N<500)
With cabergoline normoprolactinaemia, ovulatory cycles & fertility restored in 70-90%
What is a microprolactinomas typical responses to a dopamine agonist?
- Rapid fall in serum PRL (hours)
- Tumour shrinkage (days/weeks)
- Visual improvement (often within days)
- Often recovery of pituitary function
80-90% tumours show these responses & most will shrink by at least one half
