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 production of all anterior pituitary hormones?
Panhypopituitarism
List 3 characteristics of congenital panhypopituitarism
Deficient in GH + at least 1 other anterior pituitary hormone
Short stature
Hypoplastic anterior pituitary on MRI
In what order does loss of secretion occur?
Usually develops in adults with progressive loss of pituitary secretion Gonadotrophins GH Thyrotrophin Adrenocorticotrophin Prolactin
What are 3 main types of panhypopituitarism?
Simmond’s Disease
Sheehan’s Syndrome
Pituitary Apoplexy
Describe the symptoms experienced due to lack of FSH/LH, ACTH and TSH in Simmond’s disease
FSH/LH: Reduced libido, Secondary amenorrhoea, Erectile dysfunction
ACTH: Fatigue
TSH: Fatigue
State the cause of Sheehan’s syndrome and describe its onset.
Specific to postpartum women, secondary to hypotension caused by PPH.
Pituitary enlarges in pregnancy (lactotroph hyperplasia)
PPH reduces blood supply, causes pituitary infarction and thus hypopituitarism
What is pituitary apoplexy? Describe its onset.
Intra-pituitary haemorrhage or infarction.
Dramatic presentation, rapid onset
May be 1st presentation of pituitary adenoma
May be precipitated by anti-coagulants
Why is a single measurement of most hypothalamic hormones not useful?
Most hypothalamic hormones tend to be released in pulses
What do you do to test if someone is producing a hormone?
Stimulated Pituitary Function Test
What are the effects of a lack of somatotrophin in children and in adults?
Children: short stature (2 SDs < mean)
Adults: loss of GH effects are less clear
State 7 causes of short stature.
Genetic Emotional deprivation Endocrine disorders Malnutrition Malabsorption Skeletal dysplasias Systemic disease
Describe 3 causes of short stature, each with their error being in a different part of the growth axis
Hypothalamic dysfunction, lack of GHRH (PWS)
Lack of GH (Pituitary dwarfism)
GH receptor defect (Laron dwarfism)
What are most endocrine-related causes of short statue due to (with reference to the HP axis)?
Decreased production of GHRH
State which other hormones are produced in response to GH stimulation, where they are produced and their effects.
IGF I = insulin-like growth factor I + IGF II
Produced in LIVER
Mediate growth
State 3 characteristics of achondroplasia
Mutation in FGF receptor 3
Average size trunk
Short arms + legs
Name 4 causes of acquired GH deficiency in adults
Trauma
Pituitary tumour
Pituitary surgery
Cranial radiotherapy
What test is primarily used to diagnose GH deficiency?
Insulin-induced hypoglycaemia
Hypoglycaemia is a potent stimulus for GH release
State 3 other triggers for an increase in GH release.
GHRH + Arginine (i.v.)
Glucagon (i.m.)
Exercise (in kids)
Describe how the insulin-induced hypoglycaemia test is used to test GH secretion.
Normal: massive rise in GH secretion
GH Deficiency: GH response will be reduced
For each of the following anterior pituitary hormone deficiencies, state the replacement used and the parameter that is monitored during treatment:
a. ACTH
b. TSH
c. Women - LH/FSH
d. Men - LH/FSH
e. GH
a. ACTH Give hydrocortisone Monitor serum cortisol b. TSH Give thyroxine Monitor serum fT4 c. Women – LH/FSH Give E2 + progestagen Monitor symptom improvement + withdrawal bleeds d. Men – LH/FSH Give testosterone Monitor symptom improvement + serum testosterone e. GH Give GH Monitor IGF I or use growth chart (kids)
How is the human recombinant GH administered, how frequently must it be given and what further action is taken?
Subcutaneous injection daily
Monitor clinical response + adjust dose based on IGF-1 levels
State 4 signs and symptoms of GH deficiency in adults.
Reduced lean mass, Increased adiposity, Increased waist: hip ratio
Decrease plasma HDL + increased LDL
Reduced muscle strength + bulk
Impaired psychological wellbeing + quality of life
Name 5 potential benefits of GH therapy in adults
Improved body composition
Improved muscle strength + exercise capacity
Normalisation of HDL-LDL
Increased bone mineral density
Improved psychological wellbeing + quality of life
What are the potential risks of GH therapy in adults?
Increased susceptibility to cancer (but no evidence to support this)
Expensive
List the anterior pituitary hormones
FSH + LH Prolactin Growth Hormone Thyroid Stimulating hormone ACTH
What are the general causes of hypopituitarism?
Congenital (rare)
Acquired
List 8 causes of acquired panhypopituitarism
Tumour Radiation Infecion Traumatic brain injury Infiltrative disease Inflammatory Pituitary apoplexy Peri-partum infection
Describe presentation of Sheehan’s syndrome
Lethargy
Anorexia/ Weight loss
Failure of lactation
Failure to resume menses post-delivery
Why may pituitary apoplexy/adenoma cause visual field defects and headaches?
Compresses optic chiasm
Causes bitemporal hemianopia (loss of outer fields)
If squashing CN 4 or 6 in cavernous sinus = Diplopia
If squashing CN 3 = Ptosis
Describe a stimulated pituitary function test
Induce hypoglycaemia
Causes patient to produce GH + ACTH + hence cortisol (measured)
Give TRH to stimulate TSH (measure)
Give GnRH to stimulate FSH/ LH (measure)
What form of radiological test may be used to diagnose hypopituitarism?
MRI
May reveal specific pituitary pathology e.g. haemorrhage, adenoma, empty sella
What is used to predict adult height?
Mid parental height
