Year 2: Hyposecretion of anterior pituitary gland Flashcards
What are primary endocrine disorders?
Problem sits at site of the endocrine gland (producing target hormone)
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What are secondary endocrine disorders?
Problem is at the site of signalind molecules (e.g. pituitary)
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How do you call a decreased production of all anterior pituitary hormones?
Panhypopituitarism
What is the usual cause for a congenial panhypopituitarism?
How common ist it
Rare
Normally due to missing of transcription factor genees needed for normal development
What are the characteristics of congenial panhypopituitarism?
- Deficient in GH and at least 1 more anterior pituitary hormone
- Short stature
- Hypoplastic anterior pituitary gland on MRI
Name possible causes for an aquired panhypopituitarism
Tumours
- hypothalamic - craniopharyngiomas
- pituitary – adenomas, metastases, cysts
Radiation (secondary e.g. after cancer treatment)
- hypothalamic/pituitary damage
- GH most vulnerable, TSH relatively resistant
Infection eg meningitis
Traumatic brain injury
Infiltrative disease – often involves pituitary stalk
- eg neurosarcoidosis
Inflammatory (hypophysitis) (autiommune)
Pituitary apoplexy
- haemorrhage (or less commonly infarction)
Peri-partum infarction (Sheehan’s syndrome)
What is Sheehan’s syndrome?
Hypopituitarism after post partum haemorrhage
- In Pregnancy: Lactotroph hyperplasia (+ more blood supply)
- When haemorrhage in/ after birth: BP drops
- less perfusion of the Pituitary –> Pituitary infarction
- Tissue death
What is Simmond’s disease?
PANHYPOPITUITARISM
What are the signs and symptoms of panhypopituitarism?
Always depends on the deficient hormones e.g.
FSH/LH
- Secondary hypogonadism (including too little production of sex hormones)
- Reduced libido
- Secondary amenorrhoea
- Erectile dysfunction
ACTH
- Secondary hypoadrenalism (cortisol deficiency)
- Fatigue
TSH
- Secondary hypothyroidism
- Fatigue
What are the signs and symptoms for Sheehan’s Syndrome?
- •Lethargy, anorexia, weight loss – TSH/ACTH/(GH) deficiency
- •Failure of lactation – PRL deficiency
- •Failure to resume menses post-delivery
- •Posterior pituitary usually not affected
–> Difficult to pick up because all are not uncommon after pregnancy!
What is a pituitary appolplex?
How does it present?
Intra-pituitary haemorrhage or (less common) infacrction
Patients present with
- severe, sudden headache
- at later state: bitemporal hemianopia
- Cavernous sinus involvement may lead to diplopia (double vision) (IV, VI), ptosis (III) (hanging eyelid )
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Explain a bitemporal hemianopia?
What is it? Why?
Loss of temporal (lateral) vision field on both eyes
- Temporal visual information enters retinal on medial aspect of eye
- Medial fibres cross contralaterally at the optic chiasm
- Compression of the fibres at the optic chiasm might lead to bitemporal hemianopia
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Which biochemical test can you run to diagnose hypopituitarism?
May be difficult to interprete because of fluxuating hormone levels e.g.
- Cortisol- during the day
- LH/FSH - during the cycle
- GH pulsatile
- high half life T4 about 6 days
So you do a Stimulated (‘Dynamic’) Pituitary Function Tests
- Stress the body by inducing hypoglycaemia (<2.2mM)
- –> Normal function: ACTH and GH should rise + increase Glucose levels
- Additionally: Give TRH to trigger TSH production and GnRH to trigger FSH/LH production
Which radiological diagnosis could you run to diagnose a hypopituitarism?
Pituitary MRI (and MRI only)
- May reveal specific pituitary pathology
- eg haemorrhage (apoplexy), adenoma
- Empty sella – thin rim of pituitary tissue
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How would you replace GH in hypopituitarism and which check ups would you run?
Replacement: Growth hormone
Check ups:
- Check for IGF1
- and Growth charts (in children)
What are non-endocrine reasons for short stature?
- Genetic (downs syndrome, prader willis syndrome etc.
- Malnutrition
- Malabsorbtion (e..g. Cealiac disease)
- Emotional deprivation –> stress
- Systemic disease (e.g. Cystic Fibrosis)
- Skeletal dysplasia (e.g. osteogenesis imperfecta)
What are endocrine reasons for short stature?
- Cushing’s syndrome
- Hypothyroidism
- GH deficiency
- poorly controlled T1DM
What are causes of aquired GH deficiency in adults?
- TRAUMA
- PITUITARY TUMOUR PITUITARY SURGERY
- CRANIAL RADIOTHERAPY
Which test would you perform to diagnose GH deficiency?
Basically : Stress the body
- GHRH and Argninge (i.v.) (in combination more effective than each alone)
- INSULIN (i.v.) – via hypoglycaemia
- GLUCAGON (i.m.)
- EXERCISE (e.g. 10 min step climbing; when appropriate)
–> All should increase GH levels physiologically
Measure plasma GH at specific time-points (before and after)
–> If levels don’t reach a certain threshold: GH replacement
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What are symptoms of GH deficiency in adults?
- Body composition: reduced lean mass, increased adipose tissue, increased waste hip ratio
- Reduced exercise perfomance because of reduced muscle strength and bulk
- Decreased HDL, increased LDL
- Impaired ‘psychological well being’ and reduced quality of life
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What are the effects of Growthhormone replacement 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
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What are the risks and disadvantages of GH replacement in adults?
Cancer?
–> No current data to support this
Very expensive treatment
What are the effects of GH deficiancy in children?
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What is Laron Dwarfism?
Explain its origin
Dwarfism caused ba a
- Mutation in GH receptor
IGF-1 treatment in childhood can increase height
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How would you diagnose a child with short stature?
Via growth chart
- Mid-parental and predicted height can be calculated
- Then percentile curves are used to watch developments and see if they are normal or abnormal
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What are different types of dwarfism on hte hypothalamo/pituitary/organ axis?
- Prader-Willi-Syndrome: GH deficiency at the hypothalamic axis
- Pituitary dwarfism: GH deficiency (no pit. production)
- Lawrence dwarfism: GH receptor mutation
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