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Yr 2 LCRS - Endo > 1 - Hyposecretion of Anterior Pituitary Hormones > Flashcards

1 - Hyposecretion of Anterior Pituitary Hormones Flashcards

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1
Q

What are the two constituent parts of the pituitary gland?

A

Anterior Pituitary = Adenohypophysis

Posterior Pituitary = Neurohypophysis

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2
Q

What 6 hormones does the APG secrete?

A
  • TSH (Thyroid Stimulating Hormone)
  • LH (Lutenizing Hormone)
  • FSH (Follicle Stimulating Hormone)
  • GH (Growth Hormone)
  • Prolactin
  • ACTH (Adrenocorticotropic Hormone)
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3
Q

What is the group name for FSH and LH?

A

Gonadotrophins

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4
Q

Where does the adenohypophysial axis start?

A

At the hypothalamus

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5
Q

What role does the hypothalamus play in the adenohypophysial axis?

A

It makes releasing or inhibitory hormones (releasing hormones are more likely)

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6
Q

What defines a primary endocrine disease?

A

The gland at the end of the axis is functioning incorrectly.

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7
Q

What defines a secondary endocrine disease?

A

The pituitary gland itself is not functioning correctly.

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8
Q

Would TSH levels be high or low in primary hypothyroidism?

A

TSH would be high because the pituitary is functioning, but the gland at the end of the axis is not.

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9
Q

Would TSH levels be high or low in secondary hypothyroidism?

A

TSH would be low because the pituitary is not functioning.

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10
Q

Name some examples of endocrine glands.

A

Thyroid, Adrenal Cortex, Gonads

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11
Q

Explain the adenohypophysial axis.

A

Hypothalamus

APG

Endocrine Gland

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12
Q

Define Hypopituitarism

A

Decreased production of all anterior pituitary hormones or of specific hormones

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13
Q

What is panhypopituitarism and how does it differ from decreased production of just some pituitary hormones?

A

Panhypopituitarism is decreased production of all APG hormones rather than just some specific hormones.

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14
Q

Which is more rare of the causes of hypopituitarism?

A

Congenital reasons are more rare than Acquired reasons.

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15
Q

Describe why Congential Panhypopituitarism occurs

A
  • rare
  • usually due to transcription factor genes mutations needed for normal APG development
  • therefore, gland does not develop properly
  • e.g. PROP1 mutation - deficient
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16
Q

What hormones are people with Congential Panhypopituitarism are deficient in?

A

Growth Hormone and at least one more APG hormone

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17
Q

What features are typical of people with Congential Panhypopituitarism?

A
  • short stature
  • hypoplastic (underdeveloped) APG on MRI
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18
Q

What causes are there for Acquired Panhypopituitarism?

A

Tumours

Radiation

Infection

Traumatic Brain Injury

Infiltrative Disease

Inflammatory (Hypophysitis)

Pituitary Apoplexy

Peri-partum infarction (Sheehan’s Syndrome)

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19
Q

What are the different types of tumours that can cause Acquired Panhypopituitarism?

A

HYPOTHALAMIC

  • Craniopharyngiomas

PITUITARY

  • Adenomas (benign bc not cancer but still have bad effects in body)
  • Metastases
  • Cysts
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20
Q

How can radiation cause Acquired Panhypopituitarism?

A

Radiation for cancer can cause hypothalamic/pituitary damage accidentally.

Growth Hormone is most vulnerable TSH is relatively resistant and it takes a long time to lose TSH after radiotherapy.

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21
Q

Give an example of an infection that can cause Acquired Panhypopituitarism

A

Meningitis

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22
Q

Give an example of an infiltrative disease that can cause Acquired Panhypopituitarism

A

Neurosarcoidosis (condition of unknown cause featuring granulomas in various tissues, involving the central nervous system).

These infiltrative diseases often involve the pituitary stalk.

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23
Q

What is pituitary apoplexy and how can it cause Acquired Panhypopituitarism?

A

Pituitary apoplexy is bleeding into or impaired blood supply of the pituitary gland. It’s typically a haemorrhage, although it is sometimes an infarction.

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24
Q

What is another name for Panhypopituitarism?

A

Simmond’s Disease

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25
How does Panhypopituitarism clinically present?
LACK OF FSH/LH (secondary hypogonadism) * reduced libido * secondary amenorrhea (absence of period in someone who has had it before but it has stopped) * erectile dysfunction LACK OF ACTH (secondary hypoadrenalism) * cortisol deficiency * fatigue because cortisol is normally low at night, so the body thinks it is always night LACK OF TSH (secondary hypothyroidism) * fatigue
26
What is Sheehan's Syndrome?
It is a condition which describes postpartum hypopituitarism secondary to hypotension. [as a result of PPH). PPH leads to pituitary infarction. Less common in developed countries
27
What happens to the APG during pregnancy?
It enlarges. - LACTOTROPH HYPERPLASIA
28
Describe the mechanism behind Sheehan's Syndrome
1. Lactotroph Hyperplasia 2. APG grows 3. PPH during delivery 4. Blood pressure decrease 5. Hypotension 6. APG gets deprived of a sufficient blood supply 7. APG doesn't work properly 8. APG infarcts
29
What is the clinical presentation of Sheehan's Syndrome?
**TSH/ACTH/GH Deficiency** * Lethargy * Anorexia * Weight loss **Prolactin Deficiency** * Failure of lactation **FSH/LH Deficiency** * Failure of menses post-delivery
30
What happens to the PPG in Sheehan's Syndrome?
Typically, the PPG is not affected.
31
Why is Sheehan's Syndrome sometimes difficult to notice clinically?
Because: women can miss periods for quite some time postpartum women can fail to lactate weight loss/lethargy can be common post partum
32
Why can Pituitary Apoplexy presentation be quite dramatic?
This is because it is often due to an already existing adenoma. However, the intra-pituitary haemorrhage or infraction causing the apoplexy can be the first presentation of the adenoma.
33
What can precipitate a Pituitary Apoplexy?
Anti-coagulants
34
Why can a Pituitary Apoplexy affect eye-sight?
This is because the bleed is around the optic chiasm, so you lose the lateral sides of the field of vision.
35
What does a Pituitary Apoplexy look like on an MRI?
It looks like a white ring around the gap between the pituitary gland and the optic chiasm. The white is fresh blood.
36
How does a pituitary apoplexy commonly present?
* severe sudden onset headache * visual field deficit due to compressed optic chiasm (BITEMPORAL HEMIANOPIA) * cavernous sinus involvement may lead to diplopia (IV, VI), ptosis (III)
37
# Define the following: * bitemporal hemianopia * diplopia * ptosis
Bitemporal Hemianopia = a type of partial blindness where vision is missing in the outer half of both the right and left visual field. Diplopia = a technical term for double vision. Ptosis = a drooping or falling of the upper eyelid.
38
Name the 2 ways in which you could carry out biochemical diagnosis of Hypopituitarism
1) Basal plasma concentrations of pituitary/target endocrine gland hormones 2) Stimulated ('Dynamic') Pituitary Function Tests
39
What are the problems with measuring basal plasma concentrations of pituitary/target endocrine gland hormones to diagnose hypopituitarism?
- interpretation may be limited due to varying amounts of hormones in individuals at different times of day - cortisol can be undetectable at certain times of day - FSH/LH are cyclical - GH/ACTH are pulsatile **HOWEVER:** T4 is good because it has a circulating half life of 6 days
40
How do you carry out a Stimulated ('Dynamic') Pituitary Function Test to diagnose hypopituitarism?
- Render the subject hypoglycaemic via an injection of insulin and TRH (and sometimes GnRH) - Should increase ACTH and GH (the 'stress' hormones) - Cortisol is used to measure ACTH - Hypoglycaemia is \<2.2mM Insulin = should stimulate GH and ACTH TRH = should stimulate TSH GnRH = should stimulate LH/FSH
41
How can you diagnose hypopituitarism via radiography?
Pituitary MRI - may show apoplexy, no gland, adenoma etc
42
Why is hormone replacement not always 100% effective?
Because it cannot mimic natural biology entirely and prolactin can't be replaced.
43
If untreated, what can low ACTH cause?
Secondary adrenal failure
44
What therapeutic replacements can you use for the hormones of the APG?
ACTH - hydrocortisone TSH - thyroxine LH/FSH in women - HRT (E2 plus progestogen) LH/FSH in men - Testosterone GH - GH No replacement for prolactin
45
What can you check in the serum following hormone replacement to ensure that it is working?
ACTH - serum cortisol TSH - serum free T4 FH/LSH (women) - symptom improvement, withdrawal bleeds FH/LSH (men) - symptom improvement, serum testosterone GH - IGF1, growth chart for children
46
How do you treat women with low FSH/LH?
Before 50 - give oestrogen Post 50 - oestrogen and progesterone
47
What are the effects of low growth hormone in adults and children?
Children - Short stature (=2 SDs \< mean height for children of that age and sex) Adults - Effects less clear
48
How does the Growth Axis work?
Hypothalamus * releases GHRH and SS * GHRH is dominant Anterior Pituitary * releases GH * Liver makes somatomedins (esp IGF1) Target tissues * IGF1 causes growth
49
Is all short stature due to low growth hormone?
No, there are many potential cause of short stature
50
List some causes of short stature
Genetic * Down's * Turner's * Prader Willi Emotional Deprivation Systemic Disease * cystic fibrosis * rheumatoid arthiritis Malnutrition Malabsorption * coeliac Disease Endocrine Disorders * cushing's syndrome * hypothyroidism * GH deficiency * T1DM badly controlled Skeletal Dysplasia * achondroplasia * osteogenesis imperfecta
51
Why does Prader-Willi Syndrome result in short stature?
GH deficiency due to secondary hypothalamic dysfunction.
52
Why does achondroplasia result in short stature?
Not due to endocrine causes!!!! Mutation in Fibroblast Growth Factor Receptor 3 (FGF3) Abnormality in growth plate chondrocytes * Impaired linear growth Average size trunk Short arms and legs
53
Why does pituitary dwarfism result in short stature?
Due to childhood GH deficiency as a result of a small, underdeveloped pituitary gland.
54
Why does laron dwarfism result in short stature?
Mutation in GH receptor IGF1 treatment in childhood can increase height
55
How is short stature monitored?
Mid Parental Height = a predicted adult height based on mother's and father's heights Height charts with predicted growth in centimes
56
What are some causes of Acquired GH deficiency in adults?
- Trauma - Pituitary Tumour - Pituitary Surgery - Cranial - Radiotherapy
57
How can GH deficiency be diagnosed?
**Provocative Challenge (Stimulation Test)** IV GHRH + Arginine more effective as a combo or IV Insulin because it makes you hypoglycaemic and therefore causes stress or IM Glucagon (intramuscular) because it makes you sick causes stress or Exercise (if appropriate) Then measure GH at specific time points before and after
58
Why can you not just measure GH levels for diagnosis of GH deficiency?
Because it has a pulsatile release in the body (secreted in a burst-like or episodic manner rather than constantly)
59
How might a person abuse GH?
May use it to gain size/muscle mass.
60
What would happen during a Provocative Challenge for a person with GH deficiency compared to a healthy person?
Healthy * GH would increase in response Deficiency * GH stays the same or may even slightly decrease
61
What is the NICE cut off for healthy GH levels at any one time?
3mcg/L
62
How is GH deficiency treated?
Preparation * human recombinant GH (somatotropin) Administration * daily, subcutaneous injection * monitor clinical response * adjust dose to IGF-1 level
63
What are signs and symptoms of GH deficiency in adults?
Reduced lean mass * Increased adiposity (being severely overweight) * Increased waist:hip ratio Reduced muscle strength and bulk * Reduced exercise performance Decreased plasma HDL-cholesterol level * Raised plasma LDL-cholesterol level Impaired 'psychological well being' * Reduced quality of life
64
What are potential risks of GH therapy in adults?
Increased susceptibility to cancer (although no data to support this currently)
65
What is the estimated cost of lifelong GH treatment in adults?
£42K
66
What are potential benefits of GH therapy in adults?
Improved body composition – decreased waist circumference, less visceral fat Improved muscle strength and exercise capacity More favourable lipid profile - higher HDL-cholesterol, lower LDL-cholesterol Increased bone mineral density Improved psychological well being and quality of life

Yr 2 LCRS - Endo (28 decks)

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