Year 2: Hyposecretion of anterior pituitary gland Flashcards
What are primary endocrine disorders?
Problem sits at site of the endocrine gland (producing target hormone)
What are secondary endocrine disorders?
Problem is at the site of signalind molecules (e.g. pituitary)
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 )
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
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
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)
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
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
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
What are the effects of GH deficiancy in children?
What is Laron Dwarfism?
Explain its origin
Dwarfism caused ba a
- Mutation in GH receptor
IGF-1 treatment in childhood can increase height
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
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
