Hyposecretion of anterior pituitary hormones Flashcards
What are the 5 types of hormones released from the adenohypohysis
What is primary endocrine gland disease?
FSH/LH, ACTH, TSH, PROLACTIN, SOMATROPHIN (GH)
When it caused by disorder of the endocrine
gland
What is secondary endocrine gland disease?
When it is caused by disorder of the anterior pituitary
What is panhypopituitarism?
Decreased production of all anterior pituitary hormones
How can panhypopituitarism be acquired? (6)
Tumours- hypothalamic (craniopharyngiomas) and pituitary (adenomas)
Radiation-damage (GH most vuln, TSH resistant)
Infection- meningitis
Traumatic brain injury
Infiltrative disease- often involves pituitary stalk
Inflammatory-hypophysitis
Pituitary apoplexy– haemorrhage or less commonly infarction
Peri-partum infarction-sheehan’s syndrome
How else can panhypopituitarism be caused?
Congenital (rare)
Due to mutation of transcription factor genes needed for adenohypophysis development.
Deficient GH and at least 1 more adenhypophysis hormone
Panhypopituitarism also known as
simmond’s disease
Sheehan’s syndrome
what happens to pituitary
Post partum hypopituitarism
- secondary to hypotension (post partum haemorrhage-leads to pituitary infarction)
- Less common in developed countries
Anterior pituitary enlarges in pregnancy- lactotroph hyperplasia in preparation
However haemorrhage reduces blood supply to the enlarged pituitary
Gland dies off- adenohypophysis infarction
easy to miss as common symptoms
- lethargy, anorexia,weight loss
- Inability to produce milk
- Secondary ammenhorea usual after postpartum
Pituitary apoplexy caused by
Can be precipitated by
presentation in patients
Intra-pituitary haemorrhage or less commonly infarction
Anticoagulants
May be first presentation of a pituitary adenoma
- severe sudden onset
- visual field defect- compressed optic chiasm, bitemporal hemianopia
- Cavernous sinus involvement may lead to diplopia (IV,VI), ptosis. (III)
What are the symptoms of Simmond’s mainly due to?
Loss of deficient hormones -FSH/LH, ACTH, TSH
What are the symptoms of Simmond’s?
Secondary hypogonadism Secondary amenorrhoea Impotence Loss of libido Secondary hypoadrenalism (cortisol def) Tiredness Secondary hypothyroidism
What is different about Sheehan’s compared to the other two?
It is specific to women
How do you diagnose hypopituitarism?
You can’t measure hypothalamic hormones so you measure basal values of the plasma for pituitary or target endocrine gland hormones
Why will a single measurement not suffice?
Hypothalamic hormones are released in pulses
What test can you use to find out if a person is producing hormones at a normal level?
3 E.G
Another method for diagnosing Hypopituitiarism
Stimulation test
1) Inducing release of ACTH and GH
-Stress hormones
-Insulin Induce Hypoglycaemia stimulates:
GH Release
ACTH Release (Cortisol measured)
2) Inject TRH- Stimulates TSH release
3) Inject GnRH stimulates FSH and LH release
Radiological diagnosis
-Pituitary MRI
reveal pituitary pathology e.g haemorrage–> apoplexy, adenoma, empty sella
What does a lack of somatotrophin cause in children and adults?
Pituitary dwarfism in children
Effects uncertain in adults
What are other causes of short stature in children? (6)
Genetic- Down’s, Turner’s, Prader Willi
Malnutrition
Emotional deprivation
Systemic disease-C.F, Rheumatoid arthritis
Malabsorption-Coeliac
Endocrine disorders- Cushing’s, hypothyroidism, GH deficiency, poorly controlled T1DM
Skeletal dysplasia- OI
What controls GH at a hypothalamic level?
GHRH and somatostatin
What does GH (somatotrophin) stimulate the production of in the liver?
IGF-1 (insulin like growth factor) (liver is main source but is produced in many places)
IGF-2 (foetal growth)
What does IGF-1 do?
Mediate growth effects
What is laron dwarfism due to?
GH receptor defect
What is pituitary dwarfism due to
Lack of GH
Prader Willi
Dwarfism
Mutation in?
Pituitary dwarfism
Laron Dwarfism
-Can be treated by?
GH deficiency secondary to hypothalamic dysfunction
Achondroplasia
FGF3- Fibroblast Growth Factor Receptor 3
Abnormality in growth plate chondrocytes- impaired linear growth
-normal trunk, short arms and legs
-Childhood GH deficiency
-High incidence in village in Ecuador
IGF-1 treatment in childhood can increase height
Causes of acquired GH deficiency in adults
Trauma
Pituitary tumour pituitary surgery
Cranial radiotherapy
What other condition leads to hypogonadism and is a hypothalamic defect?
Prader Willi
GH provocation test
- GHRH+ARGININE (i.v) in combination more effective
- INSULIN (i.v) via hypoglycaemia
- GLUCAGON (i.m)-stimulates ant. pit. to make ACTH and GH –> patients vomit: stress dires out ACTH and GH
- EXERCISE e.g 10 mins step climbing
Measure GH before and after
Growth Hormone therapy
- preparation
- administration
-Human recombinant GH:SOMATOTROPHIN
Daily, subcutaneous injection
Monitor clinical response & adjust dose to IGF-1
GH deficiency in adults:signs and symptoms
Reduced lean mass increased adiposity, increased waist:hip ratio
Reduced muscle strength & bulk –> reduced exercise performance
Decreased plasma HDL- cholesterol and raised LDL cholesterol (bad)
Impaired psychological well being and quality of life
What is a common problem with GH therapy in adults
Increased susceptibility to cancer - no data to support this currently
Expensive
Potential benefits of GH therapy
Improved body composition- decreased waist:hip, less visceral fat
Improved muscle strength and exercise capacity
More favourable lipid profile higher HDL and reduced LDL
Increased bone mineral density
Improved psychological well being and quality of life
When is GH administered?
Daily- In the afternoon as levels are normally high at night anyway
What is the half life of GH like?
Short- 20 mins
What does GH work on hence what is its action duration like?
Protein synthesis so long
What are the adverse effects of GH?
Lipoatrophy at site of injection
Intracranial hypertension- headaches
Increased risk of cancer
What are the signs and symptoms of GH deficiency in adults?
Reduced lean mass Increased adiposity Increased waist:hip ratio Reduced muscle strength and bulk Decreased HDL and increased LDL Impaired psychological wellbeing
