Disease Profiles: Pituitary Disorders Flashcards
Define a pituitary macro-adenoma
Adenomas >1cm
Describe the use of GH antagonists in the management of acromegaly
SC injection, blocks GH activity with an 85% response rate (but tumour size does not decrease)
Last line as very expensive
Describe the clinical presentation of hypopituitarism
Depend on the specific hormone deficiency, age of onset, the rate at which hypopituitarism develops, and the underlying cause of hypopituitarism
If caused by intra/parasellar masses (e.g. pituitary macroadenomas, craniopharyngiomas) can present with headaches and visual field defects (bitemporal hemianopia)
Is pituitary adenoma which produces ACTH more likely to be a micro or macroadenoma?
Microadenoma (Cushing’s, bilateral adrenocortical hyperplasia)
Craniopharyngiomas are derived from the remnants of _______ pouch
Rathke’s
Define a pituitary micro-adenoma
Adenomas <1cm
Describe the findings in a GTT suppression test which would indicate acromegaly
GH unchanged/no suppression or paradoxical rise following oral glucose challenge (normally GH suppresses after glucose)
Name the hormone replacement for TSH deficiency
Levothyroxine
A subset of pituitary adenomas behave aggressively and enlarge more rapidly. Name two features which indicate an aggressive lesion.
Lots of mitotic figures and p53 mutations
Name the Ur/serum osmol ratio which would indicate diabetes insipidus
< 2
Describe the management of diabetes insipidus
Desmospray (nasally) or desmopressin oral tablets
Desmopressin IM injection - generally reserved for emergency or post pituitary surgery
Describe the clinical presentation of GH excess
Giant (before epiphyseal fusion)
Thickened soft tissues - skin, large jaw, sweaty, large hands
Snoring/sleep apnoea (thickened nasopharynx)
Hypertension, cardiac failure
Headaches (vascular)
Diabetes mellitus
Local pituitary effects - visual fields, hypopituitarism
Define hypopituitarism
Inadequate production of one or more pituitary hormone as a result of damage to the pituitary gland and/or hypothalamus
Name 4 pathological causes of hyperprolactinaemia
Hypothyroidism, stalk compression e.g. due to pituitary adenoma, damage to stalk, prolactinoma
How is a water deprivation test to investigate diabetes insipidus performed?
Patients stop drinking water for 2–3 hours before the first measurement
Check serum and urine osmolarities hourly for 8hr, then 4hr after giving DDAVP
What would be the consequence of ↓ TSH production (hypopituitarism)?
Secondary hypothyroidism
How would you investigate a prolactinoma (pituitary adenoma producing prolactin)?
Serum prolactin (raised)
MRI pituitary
Visual fields - bitemporal hemianopia
Other pituitary hormone tests to assess whether other hormones are being affected
Name the dynamic test used to assess the adrenal axis
Synacthen test
What are the two classes of diabetes insipidus?
Cranial (central) and nephrogeneic
Describe the management of a craniopharyngioma
Usually resection + radiotherapy
Describe the principle of management for hypopituitarism
Hormone replacement and treatment of underlying cause
What does growth hormone (GH) stimulate?
Skeletal and soft tissue growth
What would be the consequence of ↓ LH/FSH production (hypopituitarism)?
Hypogonadism
Hyper__________ may cause galactorrhoea and hypogonadism, including amenorrhoea
Hyperprolactinaemia
Name the hormone replacement for diabetes insipidus (ADH deficiency)
Desmospray (nasal) or desmopressin tablets
Pituitary macroadenomas can cause pressure _______ of normal surrounding cell tissue
Atrophy
Name 4 physiological causes of hyperprolactinaemia
Breastfeeding, pregnancy, stress, sleep
Name the most common causes of panhypopituitarism
Most commonly caused by pituitary tumours, surgery or radiotherapy
What would be the consequence of ↓ ADH production (hypopituitarism)?
Diabetes insipidus
Define hyperprolactinaemia
Abnormally high levels of prolactin in the blood
GH deficiency in children leads to ______ _______
Growth retardation
How can a pituitary macroadenoma cause visual field defects?
Compression of the optic chiasma
Name a long term side effect of somatostatin analogues in the management of acromegaly
Gallstones (inhibit gallbladder contraction)
What would be the consequence of ↓ ACTH production (hypopituitarism)?
Hypoadrenal
Define nephrogenic diabetes insipidus
Characterised by renal resistance to ADH
Describe the aquired causes of cranial (central) diabetes insipidus
Idiopathic (often autoimmune), tumours, trauma, infiltrations (sarcoidosis), infections
What is the consequence of a functioning pituitary adenoma which produces GH in an adult?
Acromegaly
Define panhypopituitarism
Refers to deficiency of all anterior pituitary hormones
Hypo_______ causes weight gain, slowness of thought and action, dry skin, cold intolerance, constipation and potentially bradycardia and hyperthermia
Hypothyroidism
How can a pituitary macroadenoma cause panhypopituitarism?
Can cause infarction
Define cranial (central) diabetes insipidus
Occurs when there is insufficient levels of circulating ADH
Describe the use of somatostatin analogues in the management of acromegaly
Monthly injections which selectively act on somatostatin receptor subtypes (highly expressed on GH-secreting tumours)
Shrink tumour (reexpands after stopping treatment)
Can be used before surgery to relieve symptoms or after surgery if GH levels fail to be normalised
What is a craniopharyngioma?
Benign tumour which typically arises in the sellar/suprasella region
In hypopituitarism, what percentage of pituitary cells must be damaged before the patient becomes symptomatic?
>80%
How could you identify cranial diabetes insipidus from a water deprivation test?
If Ur/serum osmol ratio is low and improves after DDAVP then it is due to cranial DI (not nephrogenic)
Name the condition that results from GH excess in children (before epiphyseal fusion)
Gigantism
Name 2 consequences caused by secondary hypothyroidism, hypoadrenalism, hypogonadism and GH deficiency
Tiredness/general malaise, reduced quality of life
Why might you consider GH replacement for adults with hypopituitarism?
Improve work capacity and psychological well-being
How would you investigate a craniopharyngioma?
CT/MRI
Describe the use of dopamine agonists in the management of acromegaly
PO, act on D2 receptors, work on 10-15% of patients, increased efficacy if co-secreting prolactin
How would you investigate diabetes insipidus?
Obtain baseline values then perform a water deprivation test
What would be the consequence of ↓ GH production (hypopituitarism)?
Growth failure
Describe the typical presentation of a female with hyperprolactinaemia
Generally present early with features of hyperprolactinamia:
- Galactorrhoea (30-80%)
- Menstrual irregulatity (25%)
- Decreased libido
- Ammenorrhoea
- Infertility
Describe the clinical presentation of posterior hypopituitarism
Diabetes insipidus - polyuria, polydipsia
Define diabetes insipidus
Kidneys are unable to concentrate urine
How does a functioning pituitary adenoma present?
Depends on hormone produced, prolactin is most common but can also produce FSH/LH, GH and ACTH
Name the visual field defect caused by a pituitary adenoma compressing on the optic chiasma
Bitemporal hemianopia
Name the dynamic test used to assess the adrenal and GH axes
Insulin Tolerance Test (glucagon stimulation test if ITT contraindicated)
Describe the growth of a craniopharyngioma
Slow growing, often cystic, may calcify
Name the hormone replacement for ACTH deficiency
Hydrocortisone
How would you investigate hypopituitarism?
Basal tests for relevant axis of the hypothalamo-pituitary system - LH/FSH, TSH, T4, prolactin, IGF-1 (GH axis), cortisol, Na+
Dynamic tests - synacthen test (adrenal), ITT (adrenal, GH), arginine and GH-releasing hormone (GH)
MRI if a hormone deficiency is identified to identify pituitary adenomas
Describe the clinical presentation of a craniopharyngioma
Headaches and visual disturbances
Can cause pituitary hypofunction → hormonal imbalances
Children may have growth retardation
What is a pituitary adenoma?
Benign tumour derived from cells of anterior pituitary
Name 3 short term side effects of somatostatin analogues in the management of acromegaly
Flatuence, diarrhoea, abdominal pains
Hypo__________ causes mild hypotension, hyponatreamia and CV collapse
Hypoadrenalism
Name the two peaks of incidence for the development of a craniopharyngiomas
5-15 years, 6th-7th decades
Name the most common cause of hypopituitarism in adults
Nonfunctioning pituitary macroadenomas
List 3 side effects of dopamine agonists
Have the least side effects of alternatives
Can cause N+V, low mood/depression, and may cause fibrosis of heart valves/retroperitoneal fibrosis
How would you investigate acromegaly/gigantism?
GF1 - age and sex matched, nearly always raised
Gold standard - GTT suppression test
Others - visual field, imaging to check adenoma size, pituitary function tests for other hormones
Describe the prognosis of a craniopharyngioma
Excellent prognosis (especially if <5cm)
Following radiation, SSC may develop (but rare)
How would you investigate hyperprolactinaemia?
Serum prolactin raised
Excluse physiological and drug causes then investigate pathological ones:
- Visual fields - bitemporal temianopia
- Exclude primary hypothyroidism
- Assess anterior pituitary function
- MRI pituitary
How does a non-functioning pituitary adenoma present?
Mass effects e.g. headache, visual field defects
Describe the management of a pituitary adenoma
Transphenoidal surgery
Replace hormones
Which type of drugs can cause hyperprolactinaemia?
Any drugs which reduce dopamine will reduce inhibition of prolactin so increase prolactin levels - dopamine antagonists, antipsychotics, antidepressants etc.
Pituitary micro-adenomas are much less ________ than macroadenomas
Aggressive
What is the consequence of a functioning pituitary adenoma which produces GH in a child?
Gigantism
Name the condition that results from GH excess in adults
Acromegaly
Name the hormone replacement for sex steroid deficiency
HRT/oest/prog pill for female
Testosterone for males
List 3 causes of nephrogenic diabetes insipidus
Idiopathic, familial and renal disease
Which type of Multiple Endocrine Neoplasia is associated with the formation of pituitary adenomas?
MEN1
What most commonly causes GH excess?
Nearly always due to a GH-secreting pituitary adenoma
Hypo________ leads to loss of libido, loss of secondary sexual hair, amenorrhoea and erectile disfunction, and eventually osteoporosis
Hypogonadism
Describe the management of acromegaly
Excision - transphenoidal approach
Radiotherapy +/- pharmacological treatment indicated when pituitary surgery fails to normalise
Describe the pathophysiology of pituitary carcinoma
Rare, account for <1% of pituitary tumours
Often functional (prolactin or ACTH usually)
Metastasise late after multiple recurrences
Describe the clinical presentation of diabetes insipidus
Polydipsia
Polyuria with dilute urine
Describe the familial causes of cranial (central) diabetes insipidus
Isolated in most cases, can occur as part of DIDMOAD
Describe the clinical presentation of longstanding panhypopituitarism
Gives the classic picture of pallor with hairlessness (‘alabaster skin’)
Name the dynamic test used to assess GH insufficiency
Arginine and growth hormone releasing hormone test
Describe the management of prolactimonas
Dopamine agonists normalise prolactin and shrink tumour in majority of cases - surgery rarely considered because of this
Name the two groups of causes of cranial (central) diabetes insipidus
Familial (rare)
Acquired
Describe the typical presentation of a male with hyperprolactinaemia
Impotence, generally present late with stuctural symptoms from a pituitary tumour - visual loss, headaches, anterior pituitary malfunction
Which form of malignancy is associated with GH excess?
GH excess can result in the formation of colon polyps and colon cancer - may be presenting feature
