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LCRS Year 2 - Endocrinology > Hyposecretion of Anterior Pituitary Hormones > Flashcards

Hyposecretion of Anterior Pituitary Hormones Flashcards

1
Q

What are the 5 types of anterior pituitary hormone and what are the specific hormones?

A 
Gonadotrophins - LH/FSH
Lactotropin - Prolactin 
Somatotrophin - GH (growth hormone)
Thyrotrophin - TSH
Corticotrophin - ACTH
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2
Q

What are the 3 steps in primary hormone (from endocrine gland) release, starting from the hypothalamus and why is this important?

A
  • 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

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3
Q

Which step in primary hormone release is impaired in PRIMARY endocrine gland disease?

A

Endocrine gland itself, no problem with signalling hormones to the gland but the gland is defective

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4
Q

Which step in primary hormone release is impaired in SECONDARY endocrine gland disease?

A

Anterior pituitary, production of signalling hormone is impaired, endocrine gland (e.g. thyroid) still operational but thyroid stimulating hormone is low

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5
Q

Which step in primary hormone release is impaired in TERTIARY endocrine gland disease?

A

Hypothalamus so whole process interrupted as it doesn’t communicate with the anterior pituitary

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6
Q

What is hypopituitarism?

A

Decreased production of all (panhypopituitarism) or specific anterior pituitary hormones

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7
Q

What are the two types of pan/hypopituitarism?

A

Congenital (rare)

Acquired

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8
Q

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?

A
  • 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
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9
Q

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?

A

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)

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10
Q

What is panhypopituitarism, what is it sometimes called instead of panhypopituitarism, and what are the symptoms of each case dependent on?

A

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.

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11
Q

FSH/LH can be deficient in panhypopituitarism. What is the name of the condition where FSH/LH are deficient and what are the symptoms?

A

Secondary hypogonadism

  • Reduced libido
  • Secondary amenorrhea
  • Erectile dysfunction
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12
Q

ACTH can be deficient in panhypopituitarism. What is the name of the condition where ACTH is deficient and what are the symptoms?

A

Secondary hypoadrenalism

  • Cortisol deficiency
  • Fatigue
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13
Q

TSH can be deficient in panhypopituitarism. What is the name of the condition where TSH is deficient and what are the symptoms?

A

Secondary hypothyroidism

- Fatigue

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14
Q

Where are blood vessels vulnerable in the pituitary gland?

A

Pituitary stalk between hypothalamus and pituitary gland

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15
Q

What is Sheehan’s syndrome and why does it occur?

A

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
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16
Q

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?

A

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)

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17
Q

What is pituitary apoplexy?

A

Intro-pituitary haemorrhage or infarction (bleed inside the pituitary)

18
Q

What can pituitary apoplexy present when there’s a pre-existing pituitary tumour (adenoma) and what does this mean relating to the adenoma?

A
  • 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

19
Q

What is the presentation of pituitary apoplexy?

A
  • 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)
20
Q

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?

A

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
21
Q

What is the method used to diagnosis endocrine problems that also solves the problems with basal measurement?

A

Stimulated (‘dynamic’) Pituitary Function Tests

22
Q

How does the stimulatory pituitary test work?

A

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
23
Q

Using tests for diagnosis that involve hormone levels are what kind of tests and what are tests involving MRI called?

A
  • Biochemical diagnosis

- Radiological diagnosis

24
Q

What radiological diagnosis method is used for pituitary disorder and what might it show?

A

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
25
Q

Can you or can you not replace prolactin?

A

Cannot

  • The only ant. pituitary hormone that cannot be replaced
  • Permanent loss of ability to lactate
26
Q

What is the principle behind why hormone replacement works in people with hypopituitarism?

A

The main principle is that the endocrine glands themselves and their ability to produce the hormones are not impaired
- Replacing the signalling hormone will restore something close to normal endocrine levels (cannot wholly replicate nature)

27
Q

What is the replacement hormone given and levels check when ACTH is deficient?

A
  • Hydrocortisone

- Serum cortisol

28
Q

What is the replacement hormone given and levels check when TSH is deficient?

A
  • Thyroxine

- Serum free T4

29
Q

What is the replacement hormone given and levels check in women when LH/FSH is deficient?

A
  • Estrogen + Progestogen

- Symptom improvement, withdrawal bleeds

30
Q

What is the replacement hormone given and levels check in men when LH/FSH is deficient?

A
  • Testosterone

- Symptom improvement, serum testosterone

31
Q

What is the replacement hormone given and levels check when GH is deficient?

A
  • GH itself

- IGF1, growth chart in children

32
Q

What are the steps involved in the growth axis?

A
  • Hypothalamus releases somatostatin and growth hormone releasing hormone into the anterior pituitary
  • Anterior pituitary releases somatotrophin (GH) into circulation
  • Liver is stimulated by GH to produce IGF 1/2
  • IGF 1 and GH itself act on target tissues to induce growth
33
Q

Where can problems occur in the growth axis, what is each called, and what is the common symptom seen in all cases?

A

Hypothalamus - Prader Willi syndrome
Pituitary - inability to produce GH, Pituitary Dwarfism
Liver - GH receptor defect, Laron Dwarfism

34
Q

How can each of the 3 growth axis defects be treated and why?

A
  • PWS and Pit. Dwarfism can both be treated with GH replacement as the defect occurs pre-GH release
  • Laron Dwarfism cannot be treated with GH as the defect occurs post-GH release, treatment with IGF-1 in childhood can increase height
35
Q

What is the process of GH deficiency diagnosis in children?

A

Children - Growth chart is based on parents heights and growth tracked relative to the predicted heights at each age. If they fall a certain percentile below that then an investigation takes place sometimes finding GH deficiency to be the cause

36
Q

How is GH deficiency diagnosed in adults?

A

GH provocation tests

  • GHRH + Arginine
  • Insulin (via hypoglycaemia)
  • Glucagon (makes you vomit a lot, vomiting induces the stress rather than glucagon
  • Exercise

Measure GH at specific time intervals
Should see a spike in GH levels

37
Q

What is the drug used in growth hormone therapy, how and when is it administered, how is it monitored, and what is the dose adjusted to?

A
  • Human recombinant GH (somatotropin (no ‘h’)
  • Daily, subcutaneous injection
  • Monitor clinical response
  • Adjust dose to IGF-1 levels (liver response to GH)
38
Q

What are the signs and symptoms of GH deficiency in adults?

A
  • Reduced lean mass, increased adiposity, increased waist:hip ratio
  • Reduced muscle strength and bulk, reduced exercise performance
  • Decreased plasma HDL-cholesterol, raised LDL-cholesterol
  • Impaired ‘psychological well-being’ and reduced quality of life
39
Q

There is very little data actually proving any impact of GH therapy aside from improving psychological well-being. What are the potential (theoretical) benefits of GH therapy in adults?

A
  • Improved body composition - decreased waist circumference, less visceral fat
  • Improved muscle strength and exercise capacity
  • More favourable lipid profile - higher HDL, lower LDL cholesterol
  • Increased bone mineral density
  • Improved psychological well being and quality of life
40
Q

What are the potential risks or problems of GH therapy in adults?

A
  • Increased susceptibility to cancer but NO data to support this
  • Expensive, NICE estimated cost of lifelong GH treatment in adult at £42k

LCRS Year 2 - Endocrinology (21 decks)

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