1 - Hyposecretion of anterior pituitary hormones Flashcards
(38 cards)
What are primary and secondary endocrine diseases?
primary - problem with the endocrine gland/hormone released
secondary - problem with the pituitary gland/(stimulating) hormone released
Define hypopituitarism and panhypopituitarism
Decreased production of ALL anterior pituitary hormones (PANhypopituitarism) or of specific hormones
Broadly speaking, what can panhypopituitarism be caused by?
Most likely to be acquired Congenital defects (rare) Gene mutations (more rare)
Give some causes of panhypopituitarism?
- tumours - craniopharyngiomas, adenomas, metastases and cysts
- radiation (GH is the most vulnerable and TSH is resistant)
- infection - meningitis
- traumatic brain injury
- infiltrative disease (infiltrates the pituitary stalk) e.g. sarcoidosis
- inflammatory - hypophysitis
- pituitary apoplexy
- post-partum infarction (Sheehan’s syndrome)
In what order does loss of pituitary secretion occur?
Gonadotrophins GH Thyrotrophin Corticotrophin Prolactin
What are the symptoms of someone who has developed panhypopituitarism through gene mutation of the PROP1 gene?
- deficient in GH and at least 1 other anterior pituitary hormone
- short stature
- hypoplastic pituitary on MRI
What are three main types of panhypopituitarism? Briefly describe what they are
- > Simmond’s Disease - panhypopituitarism
- > Sheehan’s Syndrome - postpartum hypopituitarism secondary to hypotension/postpartum haemorrhage
- > Pituitary Apoplexy - intra-pituitary infarction of haemorrhage
Describe the onset of Simmond’s disease and state some of its causes
onset is insidious
Can be caused by: • Infiltrative diseases • Craniopharyngioma • Cranial injury • Pituitary adenomas • Following surgery
What are the symptoms of Simmond’s disease?
(mainly due to loss of adrenal, gonadal and thyroid function)
• Impotence - GnRH
• Loss of libido - GnRH
• Secondary amenorrhoea or oligomenorrhoea - GnRH
• Fatigue - ACTH/TSH
NOTE: deficiency of GH has less of an impact in adulthood, because you have fully grown
State the cause of Sheehan’s syndrome
in pregnancy, lactotrophs become very enlarged (high prolactin) and the pituitary becomes very large. The anterior pituitary is hanging by a very thin stalk. During delivery women have a large postpartum haemorrhage., and hence the pituitary will become deprived of a decent blood supply.
Ischaemia and necrosis of the pituitary.
How does Sheehan’s syndrome present?
- failure of lactation (no prolactin)
- lethargy/anorexia/weight loss - deficiency of TSH/ACTH/GH
- failure to resume menses post delivery
What is pituitary apoplexy? Describe its onset.
Similar to Sheehan’s syndrome but isn’t specific to women
It is caused by intra-pituitary infarction or haemorrhage (in an already pre-existing adenoma (common)
This also has a RAPID presentation
What are the symptoms of pituitary apoplexy?
- visual defect field (compressed optic chiasm) - BITEMPORAL HERMIANOPIA
- severe, sudden onset headache
How can you test a person to check that their producing a hormone at a normal level?
STIMULATION/PROVOCATION TEST - administration of various releasing hormones
Why is a single measurement of most hypothalamic hormones not useful?
Most hypothalamic hormones tend to be released in pulses
How are the releasing hormones administered in stimulation/provocation tests?
intravenously
Specifically, how are each of the anterior pituitary hormones stimulated and measure in a stimulation/provocation test?
ACTH + GH - ‘street hormones’ —–> (make the person hypoglycaemic) inject insulin and measure cortisol and GH
TSH —–> give TRH and measure TSH
FSH/LH —–> give GnRH and measure FSH/LH
(if you want to have a lot at the pituitary, you can do a pituitary MRI)
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
- 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 T4 c. Women – LH/FSH Give E2 plus progestagen To check - Symptom improvement, withdrawal bleeds d. Men – LH/FSH Give testosterone Monitor libido and serum testosterone e. GH Give GH Monitor IGF I
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
Give some causes of short stature
Genetic: - Down’s syndrome - Turner’s syndrome - Prader-Willi syndrome Emotional Deprivation Systemic disease - Cystic Fibrosis - Rheumatoid arthritis Malnutrition Malabsorption - Coeliac disease Endocrine Disorders - Cushing’s syndrome - Hypothyroidism - GH deficiency - poorly controlled T1DM Skeletal dysplasias - Achondroplasia - osteogenesis imperfecta
Describe the growth axis
- hypothalamus stimulates the release of GHRH (and inhibitory somatostatin)
- GH is released from the anterior pituitary
- GH acts as a hormone, but also stimulates the liver to produce IGF I, which mediates growth effects
Briefly describe the causes of short stature in children
Prader-Willi syndrome
Pituitary dwarfism
Laron Dwarfism
