Hyposecretion of Anterior Pituitary Hormones Flashcards
What is the difference between primary, secondary and tertiary endocrine gland disease?
Primary – problem with the endocrine gland/hormone released
Secondary – problem with the pituitary gland/hormone released
Tertiary – problem with the hypothalamus
What is the term given to decreased secretion of all anterior pituitary hormones?
Panhypopituitarism
What are three main types of panhypopituitarism?
Simmond’s Disease
Sheehan’s Syndrome
Pituitary Apoplexy
Describe the onset of Simmond’s disease
Very slow onset
State the cause of Sheehan’s syndrome
This is specific to WOMEN
It is caused by vasoconstrictor spasm of hypophysial arteries as a result of post-partum haemorrhage
This spasm causes pituitary infarction
What is pituitary apoplexy? Describe its onset.
This is similar to Sheehan’s syndrome but isn’t specific to women
It is caused by intra-pituitary infarction or haemorrhage potentially from a tumour This also has a RAPID presentation
Why is a single measurement of most hypothalamic hormones not useful?
Most hypothalamic hormones tend to be released in pulses
What type of test do you do to test if someone is producing a hormone?
Stimulation/provocation test
What is the name given to the secondary endocrine gland failure that results from a lack of corticotrophin release from the pituitary?
Hypoadrenocorticalism
What are the effects of a lack of somatotrophin in children and in adults?
Children – stunted growth (pituitary dwarfism)
Adults – loss of GH effects are uncertain
State some causes of short stature.
Genetic
Malnutrition
Emotional deprivation
Endocrine disorders
State some acquired causes of GH deficiency in children.
Tumours of the hypothalamus and pituitary Other intracranial tumours nearby (e.g. optic nerve glioma) Irradiation Head injury Infection or inflammation Severe psychosocial deprivation
As well as being its own hormone, GH stimulates the production of other hormones. State one important hormone that is stimulated by GH, its side of production and its effects.
IGF I = insulin-like growth factor I
It is produced in the LIVER
It mediates growth effects
What type of dwarfism is caused by a GH receptor defect?
Laron Dwarfism
Describe the IGF I levels in people with this Laron dwarfism.
LOW IGF I
Because functioning GH receptors are necessary for GH to stimulate the production of IGF I
Why are the Pygmies in Africa naturally short?
Their IGF I doesn’t function properly
Using GnRH as an example. State one example of tertiary hypopituitarism
Prader-Willi Syndrome
What is the gold standard method of testing the ability of the pituitary to release growth hormone?
Insulin-induced hypoglycaemia
Hypoglycaemia is a potent stimulus for growth hormone release
State three other triggers for an increase in GH release.
Arginine
Glucagon
Exercise
Describe how the insulin-induced hypoglycaemia test is used to test GH secretion.
In a normal subject, the insulin-induced hypoglycaemia will give a massive rise in GH secretion
If you have a partial deficiency of GH then your response will be reduced
State some of the effects of growth hormone therapy in children and what groups of children respond better
Increased linear growth
Decease in body fat
Younger children respond better
Obese children respond better
How is the human recombinant GH used in GH therapy administered and how frequently must it be given?
Subcutaneous or Intramuscular
It is given daily or 4/5 times a week
Describe the absorption, metabolism and duration of action of the GH therapy
It has a maximal plasma concentration after 4-6 hours
Metabolism – renal and hepatic with a short half-life (20 mins)
Duration of action – it works on protein synthesis so it’s duration of action is going to be quite long.
IGF I levels peak after around 20 hours
State some adverse effects of GH therapy.
GH is also a cell stimulation hormone so there is an increased risk of tumours
