Endo 1 - Hyposecretion of APG Hormones Flashcards
Achondroplasia is not an endocrine cause of short stature. But what is it?
Dwarfism caused by mutation in the Fibroblast Growth Factor receptor 4 (FGF3).
Abnormal growth plate chondrocytes which impairs linear growth
Short limbs but average size trunk
What is a chondrocyte?
Cells which secrete cartilage matrix
How can Laron dwarfism be treated?
IGF-1 can be given
Name 3 causes of acquired GH deficiency in adults
Trauma
Pituitary tumour
Cranial radiotherapy
Why is measuring GH randomly not a good idea?
GH release is pulsatile
GH is measured under stress. What are the GH provocation tests?
- Insulin - GH release via hypoglycaemia
- Glucagon (i.m)
- GHRH and Arginine (combined)
- Exercise (children better)
Plasma GH measured at time points before and after
How is Growth hormone administered?
Daily subcutaneous injection given. Clinical response monitored and dose adjusted to IGF-1
What are the signs and symptoms of GH deficiency
- Impaired psychological wellbeing
- Decreased HDLs, more LDLs
- Reduced muscle strength and bulk
- Reduced lean mass, increased waist:hip ratio
- increased adiposity
What are the benefits of taking GH?
Improved body composition, better lipid profile, increased muscle strength and exercise capacity, increased bone mineral density, improved psychological well being
What are the potential risks of GH therapy in adults?
- (Increased susceptibility to cancer but not evidence supported)
- V expensive (42k for lifelong GH treatment)
What are the 5 APG hormones?
- GH
- Prolactin
- TSH
- LH/FSH
- ACTH (used to make cortisol)
Differentiate between 1 and 2 endocrine gland disease?
1 = when the gland at the end of the chain isn't working 2 = problem with secretion of hormone
What are some features of primary hypothyroidism?
High TSH, Low T4
What is panhypopituitarism?
Decreased production of all APG hormones
Hypopituitarism can be a decrease in production of specific hormones also.
t
Describe congenital causes of hypopituitarism?
TF genes are mutated (e.g. PROP1). GH deficient and at least one other APG hormone.
Short stature, hypoplastic APG on MRI
Name the causes of panhypopituitarism
- Tumour (hypothalamic/pituitary)
- Radiation
- Infection
- Traumatic brain injury
- Infiltrative disease
- Inflammatory
- Pituitary apoplexy
- Peri-partum infarction
What are hypothalamic tumours called?
Craniopharyngiomas
What are pituitary tumours called
Adenoma (pituitary)
Which hormone is most resistant to radiation damage?
TSH
Which hormone is most susceptible to radiation damage?
GH
Give an example of an infiltrative disease that can cause panhypopituitarism
Neurosarcoidosis - diseases typically involve pituitary stalk
How can panhypopituitarism present?
- Low FSH/LH = secondary hypogonadism, secondary amenorrhoea, reduced libido, erectile dysfunction
- Low ACTH = secondary hypoadrenalism - fatigue
- Low TSH = secondary hypothyroidism - fatigue
How does Sheehans syndrome arise?
aka peri-partum infarction
- Pregnancy - prolactin produced so lactotrophs grow - APG grows.
- APG has very little blood supply and may cause potential impingement
- Higher risk of haemorrhaging (higher risk in poorer countries).
- Haemorrhaging means APG doesn’t get enough blood so infarcts
How does Sheehans syndrome present?
Lethargy, anorexia, weight loss due to TSH/ACTH/GH deficiency.
MAJORLY, failure to lactate due to prolactin deficiency. Failure to resume menstruation
PPG usually unaffected
What is pituitary apoplexy?
Haemorrhaging of the pituitary gland. May present if patient has pre-existing pituitary tumour
What is often the first presentation of pituitary adenoma?
Pituitary apoplexy which causes severe sudden headache with visual field defect (due to compressed optic chiasm - bitemporal hemianopia). May also cause diplopia (IV, V) or Ptosis (III)
Pituitary apoplexy may be precipitated by what?
Anticoagulants
Why shouldn’t basal concentrations of APG hormones really be measured?
ACTH/GH = pulsatile
FSH/LH = cyclical
Cortisol = time dependent
T4 = long half life (6 days)
How is hypopituitarism biochemically diagnosed?
Insulin injection - BG < 2.2mM -> stimulates GH release and ACTH release (cortisol measured)
TRH given - stimulates TSH
GnRH - FSH and LH release
ACTH deficiency. Treat
Hydrocortisone - check serum cortisol
TSH deficiency. Treat
Give thyroxine - check serum free t4
FSH/LH deficiency in woman. Treat
HRT (E2 and progestogen) - check symptom improvement and withdrawal bleeds
FSH/LH deficiency in man. Treat
Testosterone - check symptom improvement and serum testosterone
GH deficiency. Treat
GH - check IGF-1 and growth chart (if child)
