Hyposecretion of Anterior Pituitary Hormones Flashcards
What are the 5 types of anterior pituitary hormone and what are the specific hormones?
Gonadotrophins - LH/FSH Lactotropin - Prolactin Somatotrophin - GH (growth hormone) Thyrotrophin - TSH Corticotrophin - ACTH
What are the 3 steps in primary hormone (from endocrine gland) release, starting from the hypothalamus and why is this important?
- Hypothalamus releases releasing/inhibiting hormone to anterior pituitary
- Anterior pituitary produces an anterior pituitary hormone
- Anterior pituitary hormone signals to endocrine gland which produces primary hormone
Endocrine gland disease type is defined by which step has disorder
Which step in primary hormone release is impaired in PRIMARY endocrine gland disease?
Endocrine gland itself, no problem with signalling hormones to the gland but the gland is defective
Which step in primary hormone release is impaired in SECONDARY endocrine gland disease?
Anterior pituitary, production of signalling hormone is impaired, endocrine gland (e.g. thyroid) still operational but thyroid stimulating hormone is low
Which step in primary hormone release is impaired in TERTIARY endocrine gland disease?
Hypothalamus so whole process interrupted as it doesn’t communicate with the anterior pituitary
What is hypopituitarism?
Decreased production of all (panhypopituitarism) or specific anterior pituitary hormones
What are the two types of pan/hypopituitarism?
Congenital (rare)
Acquired
It’s very uncommon to have congenital panhypopituitarism. Why does it occur, what is its definition in terms of hormone deficiency, what physiological symptoms does it cause, and what would you see on an MRI?
- Usually due to underdeveloped ant. pituitary, mutations in transcription factor genes needed for normal ant. pituitary development
- Deficient in GH and at least 1 more ant. pituitary hormone
- Short stature
- Hypoplastic (underdeveloped) ant. pituitary gland on MRI
It’s much more common that something happens to the ant. pituitary gland rather than to be born with problems. What are the 8 causes of acquired hypopituitarism?
Tumours
- hypothalamic
- pituitary
Radiation
- hypothalamic/pituitary damage
- GH most vulnerable, TSH relatively resistant
Infection
Traumatic brain injury
Infiltrative disease
- Often involves pituitary stalk e.g. neurosarcoidosis
Inflammation
- Hypophysitis, autoimmune damage to pituitary gland
Pituitary apoplexy
- haemorrhage or infarction
Peri-partum infarction (Sheehan’s syndrome)
What is panhypopituitarism, what is it sometimes called instead of panhypopituitarism, and what are the symptoms of each case dependent on?
Deficiency of GH and at least 1 more ant. pituitary hormone
- Sometimes called Simmond’s disease
Symptoms are dependent upon deficient hormones. Mainly due to decreased thyroidal, gonadal and adrenal function.
FSH/LH can be deficient in panhypopituitarism. What is the name of the condition where FSH/LH are deficient and what are the symptoms?
Secondary hypogonadism
- Reduced libido
- Secondary amenorrhea
- Erectile dysfunction
ACTH can be deficient in panhypopituitarism. What is the name of the condition where ACTH is deficient and what are the symptoms?
Secondary hypoadrenalism
- Cortisol deficiency
- Fatigue
TSH can be deficient in panhypopituitarism. What is the name of the condition where TSH is deficient and what are the symptoms?
Secondary hypothyroidism
- Fatigue
Where are blood vessels vulnerable in the pituitary gland?
Pituitary stalk between hypothalamus and pituitary gland
What is Sheehan’s syndrome and why does it occur?
Post-partum hypopituitarism secondary to hypotension
- Pituitary is enlarged in pregnancy due to more prolactin production and requires more blood supply
- If the mother has a post-partum haemorrhage (PPH) then she becomes hypotensive resulting in insufficient blood reaching the pituitary gland
- The pituitary gland then infarcts and dies off due to lack of blood supply
Sheehan’s syndrome is insidious in its onset due to the mother feeling lethargic and tired after having a baby. How does Sheehan’s syndrome present and which deficiencies are responsible for each symptom?
Lethargy, anorexia, weight loss - TSH/ACTH/GH deficiency
Failure of lactation (KEY SYMPTOM) - Prolactin deficiency
Failure to resume menstruation post-delivery (difficult to tell due to taking several months to normally resume)
What is pituitary apoplexy?
Intro-pituitary haemorrhage or infarction (bleed inside the pituitary)
What can pituitary apoplexy present when there’s a pre-existing pituitary tumour (adenoma) and what does this mean relating to the adenoma?
- Dramatic presentation in presence of pre-existing adenoma
- May be the first sign of an adenoma even being there as they’re fairly common in the population with no symptoms
What is the presentation of pituitary apoplexy?
- Severe sudden onset headache
- Visual field defect - optic chiasm lies just above pituitary so can become compressed (bitemporal hemianopia)
- Cavernous sinus involvement may lead to interference with cranial nerves, may cause diplopia (double vision, CN IV, VI) and ptosis (droopy eyelid, CN III)
What are some problems with measuring of basal plasma concentrations of pituitary or target endocrine gland hormones in terms of trying to make a diagnosis?
Interpretation may be limited as many hormones are pulsatile (levels go up and down)
- checking cortisol levels depends on time of day e.g. might be low because its naturally low at that time of day
- T4 has a long half-life (6 days) such that you might have hypothyroidism but you wouldn’t be able to tell
- FSH/LH are cyclical and GH/ACTH are pulsatile so their levels naturally fluctuate
What is the method used to diagnosis endocrine problems that also solves the problems with basal measurement?
Stimulated (‘dynamic’) Pituitary Function Tests
How does the stimulatory pituitary test work?
ACTH and GH are hormones released in times of ‘stress’ such as in hypoglycaemia
- Insulin is injected to induce hypoglycaemia and GH/ACTH (measured as cortisol) release is measured
- TRH is injected to assess TSH release
- GnRH is injected to assess FSH/LH release
Using tests for diagnosis that involve hormone levels are what kind of tests and what are tests involving MRI called?
- Biochemical diagnosis
- Radiological diagnosis
What radiological diagnosis method is used for pituitary disorder and what might it show?
Pituitary MRI
- May reveal specific pituitary pathology e.g. haemorrhage (apoplexy) or an adenoma
- May reveal an empty sella - basically that there’s no pituitary there at all, thin rim of pituitary tissue
