Hypo secretion of Anterior Pituitary Hormones Flashcards
Primary, secondary and tertiary endocrine gland diseases
Primary - Disorder at the endocrine gland
Secondary -disorder at the pituitary gland
Tertiary - disorder at the hypothalamus
Panhypopituitarism
Decreased production of all anterior pituitary hormones
Panhypopituitarism is caused by
Congenital –> rare defects or gene mutations in the genes involved in the development of the gland (e.g. PROP1). Hypo plastic pituitary gland
Acquired --> radiotherapy tumours infection trauma infiltrative disease inflammatory pituitary apoplexy post partum infarction
Panhypopituitarism causes progressive loss of the hormones in this order:
Gonadotrophin’s (LH and FSH)
GH
Thyrotrophin
Corticotrophin (ACTH)
Prolactin deficiency is uncommon
Simmon’s disease is
Caused by…
Slow and insidious in onset. Panhypopituitarism
Various: infiltrative processes e.g. lymphocytic Pituitary adenomas Craniopharyngiomas Cranial injury Following surgery
Simmond’s disease symptoms due to….. and include results in/symptoms:
decreased function of the thyroid, adrenals, and gonads
Result: Oligomenorrhoea/ secondary amenorrhoea in women Impotence in men Decreased libido Tiredness Waxy skin Loss of body hair Hypotension
Diagnosis of hypopituitarism can be made by
Biochemical diagnosis - using basal plasma levels of pituitary or target endocrine hormones. (hypothalamus pulsatile so one measurement shows nothing)
Provocation/stimulation test.
For ACTH and GH - induce stress, inject insulin to induce hypoglycaemia
For TSH - give TRH
For FSH/LH - give GnRH
Radiological analysis - can spot apoplexy (haemorrhage/infarction); adenoma; empty sella turcica
Sheehan’s syndrome is
Postpartum ypopituitarism specific in women
Sheehan’s syndrome is caused by
Post-partum haemorrhage –> hypovolaemic shock and blood loss.
Leads to pituitary infarction
Blood loss in the vasoconstrictor spasm of hypophyseal arteries and this leads to:
- Ischaemia of the pituitary (which is enlarged during pregnancy due to lactotroph hyperplasia).
- Necrosis of the pituitary
Panhypopituitarism will occur in adults with …
progressive loss of pituitary secretion
3 main types of Panhypopituitarism
- Simmond’s Disease
- Sheehan’s Syndrome
- Pituitary Apoplexy
Presentation of Sheehan’s is
fast
Presentation of Pituitary apoplexy is
fast
in pituitary adenoma
Pituitary apoplexy is
Caused by
Similar to Sheehan’s but not specific to women
Intra-Pituitary infarction / haemorrhage
Pituitary apoplexy - there is rapid presentation in
patients with pre-existing pituitary tumours which suddenly infarct
A deficiency in a single adenohypophysial hormone results in
secondary endocrine gland failure
Examples of secondary endocrine gland failure:
o Gonadotrophin
o Thyrotrophin
o Corticotrophin
-Hypogonadism
-Hypothyroidism
‐Hypoadrenocorticalism
Signs and symptoms of panhypopituitarism
decreased FSH/LH - secondary hypogonadism - secondary amenorrhoea, decreased libido, erectile dysfunction
decreased ACTH - secondary hypoadrenalism - fatigue
decreased TSH - secondary hypothyroidism - fatigue, weight gain
Signs and symptoms of Sheehan’s syndrome
lethargy anorexia weight loss no lactation don't resume menses
Signs and symptoms of pituitary apoplexy
severe sudden headache
bitemporal hemianopia - pressed onto the optic chasm
diplopia
ptosis
Hormone replacement therapy and how to check for ACTH TSH Women LH/FSH Men LH/FSH GH
ACTH - hydrocortisone. Check serum cortisol.
TSH - thyroxine. Check serum free T4.
Women LH/FSH. HRT (E+P). Check by alleviation of symptoms and bleeds
Men LH/FSH. Testosterone. Check by alleviation of symptoms and serum testosterone
GH - GH. Check IGF-1/ growth chart for children.
Endocrine causes of short stature
Lack of GH (pituitary dwarfism)
Cushing’s
Hypothyroidism
Poorly controlled T1DM
Non endocrine causes of short stature
genetic - down's, turner's, Prader Willi Emotional deprivation Malnutrition/ malabsorption systemic disease Skeletal dysplasia e.g. achondroplasia/ Osteogenesis I
Describe the growth axis
hypothalamus –> adenohypophysis –> GHRH –> GH –> target tissues / liver –> IGF I –> target tissues
Diagnosis of short stature
Growth chart of mid parental height
GH provocation test, giving:
- GHRH and arginine IV
- insulin IV – hypoglycaemia
- Glucagon IM
- Exercise
Measure plasma GH (no response). Low plasma IGF-1
whereabouts of the growth axis is affected with:
PW syndrome
Pituitary dwarfism
Laron dwarfism
PW — GH deficiency caused by hypothalamus dysfunction
Pituitary dwarfism — childhood lack of GH produced from pituitary
Laron dwarfism — GH receptor defect (on liver) so IGF-I not produced
Treatment
Somatotrophin given 4/5x per week
Signs of GH deficiency in adults
increased adiposity increased waist:hip ratio decreased muscle decreased HDL increased LDL decreased psychological wellbeing
pros and cons of therapy in adults
+ reverse signs + increases bone density
- increased risk of CVS effects - increased soft tissue growth (cardiomegaly) - increased risk of cancer
