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

Hyposecretion of Anterior Pituitary Hormones Flashcards

07.10.2019

1
Q

What is the tissue type of the anterior and posterior pituitary?

A

AP: glandular tissue (upward growth from buccal cavity)
PP: neural tissue (downward growth from the base of the brain)

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2
Q

What are the anterior pituitary hormones and cell types?

A 
FSH/LH (gonadotrophs)
PROLACTIN (lactotrophs)
GH = somatotrophin (somatotrophs)
TSH (thyrotrophs)
ACTH (corticotrophs)
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3
Q

What is a secondary endocrine gland disease?

A

The problem lies within the anterior pituitary

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4
Q

What is a primary endocrine gland disease?

A

The problem lies within the endocrine gland itself, e.g. thyroid, adrenal cortex, gonads…

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5
Q

Hypopituitarism

A

DECREASED PRODUCTION OF ALL ANTERIOR PITUITARY HORMONES (PANHYPOPITUITARISM) OR: OF SPECIFIC HORMONES

-> CONGENITAL (rare) or ACQUIRED

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6
Q

What is a decreased production of all AP hormones called?

A

Panhypopituitarism

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7
Q

Congenital panhypopituitarism

A
  • rare
  • usually due to a mutation of TF genes needed for normal AP development
  • deficient in GH and at least one other AP hormone
  • short stature
  • hypoplastic pituitary gland on MRI
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8
Q

What is a mutation that can cause congenital panhypopituitarism?

A

PROP 1 -> the expression of PROP1 leads to ontogenesis of pituitary gonadotropes as well as somatotropes, lactotropes and caudomedial thyrotropes.

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9
Q

“Ontogenesis”

A

The development of an individual organism or anatomical or behavioural feature from the earliest stage to maturity.

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10
Q

Acquired Panhypopituitaruism (Causes)

A
  • Tumors (hypothalamic: craniopharyngioma; pituitary: adenomas, metastases, cysts)
  • Radiation (-> hypothalamic/pituitary dmagage; GH is most vulnerable, TSH is relatively resistant)
  • Infection (e.g. meningitis)
  • Traumatic Brain Injury
  • Infiltrative diseases (-> often involve the pituitary stalk e.g. neurosarcoidosis)
  • Inflammatory (hypophysitis)
  • Pituitary Apoplexy (haemorrhage or less common infarction)
  • Peri-partum infarction (Sheehan’s Syndrome)
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11
Q

How does Panhypopituitarism present?

A

FSH/LH: Secondary hypogonadism

  - > Reduced libido
  - > Secondary amenorrhoea
  - > Erectile dysfunction

ACTH: Secondary hypoadrenalism (cortisol deficiency)
-> Fatigue

TSH : Secondary hypothyroidism
-> Fatigue

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12
Q

Simmond’s disease

A

Panhypopituitarism is occasionally called this.

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13
Q

What part of the pituitary is affected in Sheehan’s syndrome?

A

Only the anterior pituitary.

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14
Q

Sheehan’s Syndrome

A
  • Post-partum hypopituitarism secondary to hypotension. PPH (post partum haemorrhage) leads to pituitary infarction.
  • less common in developed countries
  • pituitary increases in size in pregnancy due to lactotroph hyperplasia
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15
Q

How does Sheehan’s syndrome present?

A
  • Lethargy, anorexia, weight loss – TSH/ACTH/(GH) deficiency
  • Failure of lactation – PRL deficiency
  • Failure to resume menses post-delivery
  • Posterior pituitary usually not affected
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16
Q

Pituitary Apoplexy

A
  • Intra-pituitary haemorrhage or (less commonly) infarction
  • Often dramatic presentation in patients with pre-existing pituitary tumours (adenomas)
  • May be first presentation of a pituitary adenoma
  • Can be precipitated by anti-coagulants
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17
Q

Diplopia

A

Double vision

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18
Q

Ptosis

A

Droopy upper eyelid

19
Q

How does pituitary apoplexy present?

A
  • SEVERE sudden onset headache
  • Visual field defect – compressed optic chiasm, bitemporal hemianopia
  • Cavernous sinus involvement may lead to diplopia (IV, VI), ptosis (III)
20
Q

How can you diagnose hypopituitarism? (simple)

A
  • biochemical tests (basal plasma levels or dynamic tests)

- radiology (pituitary MRI)

21
Q

Biochemical methods to diagnose hypopituitarism

A
  1. Basal plasma concentrations of pituitary or target endocrine gland hormones;
    HOWEVER:
    • interpretation may be limited
    • undetectable cortisol – what time of day?)
    • T4 – circulating t1/2 6 days
    • FSH/LH – cyclical
    • GH/ACTH - pulsatile
  2. Stimulated (‘Dynamic’) Pituitary Function Tests
    • ACTH & GH = ‘stress’ hormones
      -> Hypoglycaemia (<2.2mM) = ‘stress’
      -> Insulin-induced hypoglycaemia stimulates
      • GH release
      • ACTH release (cortisol measured)
    • TRH stimulates TSH release
    • GnRH stimulates FSH & LH release
22
Q

Radiological methods to diagnose hypopituitarism

A

Pituitary MRI
- May reveal specific pituitary pathology (eg haemorrhage (apoplexy), adenoma)

  - Empty sella – thin rim of pituitary tissue
23
Q

How do you treat Hypopituitarism?

A

Hormone replacement and check hormone levels to make sure that the dose is right.

-> see powerpoint cards

24
Q

What does growth hormone deficiency cause?

A

Children: short stature (2SD < mean height of children that same age and sex)

Adults: effects less clear

25
Q

What are genetic causes of short stature?

A

Down Syndrome
Turner syndrome
Prader Willi Syndrome

26
Q

What are the causes for short stature

A
  • genetic
  • emotional deprivation
  • systemic disease (CF, rheumatoid arthritis)
  • Malnutrition
  • Malabsorption (e.g. coeliac disease)
  • endocrine disorders (Cushing’s syndrome, hypothyroidism, GH deficiency, uncontrolled T1DM)
  • skeletal dysplasias ( achondroplasia, osteogenesis imperfecta)
27
Q

What are some endocrine disorders that cause short stature?

A
  • Cushing’s syndrome
  • hypothyroidism
  • GH deficiency
  • poorly controlled T1DM
28
Q

Cushing’s syndrome vs disease

A

S: cause unknown
D: pituitary adenoma

(excessive cortisol)

29
Q

skeletal dysplasia causes for short stature

A
  • Achondroplasia

- Osteogenesis imperfecta

30
Q

What can cause short stature due to malabsorption?

A

Coeliac disease

31
Q

What are IGFI and IGFII?

A

Insulin like growth factors 1 and 2

When GH is secreted it acts on the liver and IGFI and IGFII are set free and act on body tissues.

32
Q

Laron Dwarfism

A
  • due to GH receptor mutation
  • IGF-1 treatment in childhood can increase height
  • High incidence in a specific village in Ecuador – descendants of Spanish Sephardic Jews fleeing Spain during Inquisition
33
Q

Pituitary dwarfism

A

lack of GH

34
Q

Dwarfism (Achondroplasia)

A
  • Mutation in Fibroblast Growth Factor Receptor 3 (FGF3)
  • Abnormality in growth plate chondrocytes - impaired linear growth)
  • Average size trunk
  • Short arms and legs
35
Q

What are causes of acquired GH deficiency in adults?

A
  • TRAUMA
  • PITUITARY TUMOUR PITUITARY SURGERY
  • CRANIAL RADIOTHERAPY
36
Q

How can you diagnose GH deficiency?

A
  • random blood test is of little use as the levels are pulsatile
  • PROVOCATION CHALLENGE (i.e. stimulation test)
37
Q

What are signs of GH deficiency?

A
  • Reduced lean mass, increased adiposity, increased waist:hip ratio
  • Reduced muscle strength & bulk -> reduced exercise performance
  • Decreased plasma HDL-cholesterol & raised LDL-cholesterol
  • Impaired ‘psychological well being’ and reduced quality of life
38
Q

What are the downsides of GH therapy in adults?

A

Increased susceptibility to cancer
– no data to support this currently

Expensive – NICE estimated cost of lifelong GH treatment in adult = £42K

  • Daily injections
39
Q

Potential 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-cholesterol, lower LDL-cholesterol
  • Increased bone mineral density
  • Improved psychological well being and quality of life
40
Q

GH Therapy

A
  • Preparation: Human recombinant GH (approved name: SOMATOTROPIN)
  • Administration: Daily, subcutaneous injection; Monitor clinical response & adjust dose to IGF-1
41
Q

Do patients with Prader Willi Syndrome respond to GH?

A

Yes they do.

The problem with Prader Willi and short stature lies within the hypothalamus.

42
Q

What are some possible GH provocation tests?

A
  • GHRH and Arginine (in marmite) i.v. should increase GH
  • Insulin via hypoglycaemia should cause GH release
  • Glucagon i.m. causes GH and ACTH increase (makes you vomit, so probably through the stress of that)
  • exercise (done in children)

-> measure GH levels before and after

43
Q

Summarise congenital panhypopituitarism

A
  • rare
  • usually due to a mutation in a TF needed for normal AP development.
  • e.g. PROP1 -> deficient in GH and at least one more AP hormone
  • short stature and hypoplastic AP on MRI

Year 2 - LCRS - Endocrinology (18 decks)

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