Hypopituitarism Flashcards
What are the 5 main hormones made by the anterior pituitary?
Growth Hormone (Somatotrophin) Prolactin TSH ( Thyroid stimulating hormone) LH, FSH - both gonadotrophin's ACTH (Adrenocorticotrophic hormone)
What regulates the anterior pituitary hormone production?
Hypothalamic releasing or inhibitory factors travel in the portal circulation to regulate anterior pituitary hormone production.
What is primary disease?
gland itself fails, e.g. primary hypothyroidism
What is secondary disease?
no signals from hypothalamus or anterior pituitary, e.g. secondary hypothyroidism
What are congenital causes for hypopituitarism?
Rare, usually due to mutations of transcription factor genes needed for normal anterior pituitary development..
Would be deficient in GH and at least 1 more anterior pituitary hormone. Short stature, hypoplastic (underdeveloped APT on MRI).
What are the causes of Acquired hypopituitarism?
Much more common.
Tumours eg adenomas, metastases, cysts
Radiation (hypothalamic/pituitary damage)
Infection eg meningitis
Traumatic brain injury
Pituitary surgery
Inflammatory (hypophysitis)
Pituitary apoplexy - haemorrhage (or less commonly infarction)
Peri-partum infarction (Sheehan’s syndrome)
What is panhypopituitarism?
Total loss of anterior & posterior pituitary function.
How can you get hypopituitarism due to radiotherapy?
Pituitary and hypothalamus both sensitive to radiation. radiotherapy could be direct or indirect and damage done would be dependent on the dose delivered. Hormones that are most sensitive GH & gonadotrophin’s. Risk can persist for up to 10 years after therapy so yearly assessment is required.
Which hormone may actually increase as a result of radiotherapy damage to the hypothalamo-pituitary axis?
Prolactin, loss of hypothalamic dopamine which is an inhibitor.
What would a reduction in FSH/LH present as?
Reduced libido
Secondary amenorrhoea
Erectile dysfunction
Reduced pubic hair
What would a reduction in ACTH present as?
Fatigue
Not a salt losing crisis (renin-angiotensin)
What would a reduction in TSH present as?
Fatigue
What would a reduction in Growth hormone present as?
Short stature for children
Reduced quality of life
What would a reduction in Prolactin present as?
Inability to breastfeed
What is Sheehan’s syndrome?
Post-partum hypopituitarism secondary to hypotension (post partum haemorrhage - PPH)
More common in developing countries
Anterior pituitary enlarges in pregnancy (lactotroph hyperplasia)
PPH leads to pituitary infarction.
What is the presentation of Sheehan’s syndrome?
Lethargy, anorexia, weight loss – TSH/ACTH/(GH) deficiency
Failure of lactation – PRL deficiency
Failure to resume menses post-delivery
Posterior pituitary usually not affected
What is the best radiological way to visualise the pituitary gland?
MRI
What is pituitary apoplexy?
Intra-pituitary haemorrhage or (less commonly) infarction
Often dramatic presentation in patients with pre-existing pituitary tumours (adenomas)
May be first presentation of a pituitary adenoma
Can be precipitated by anti-coagulants
What is the presentation for pituitary apoplexy?
Lethargy, anorexia, weight loss – TSH/ACTH/(GH) deficiency
Failure of lactation – PRL deficiency
Failure to resume menses post-delivery
Posterior pituitary usually not affected
What is the best way to diagnose hypopituitarism?
Dynamic pituitary function test, taking a series of hormone measurements over a series of time points.
What is measured in a dynamic pituitary function test?
ACTH & GH = ‘stress’ hormones Hypoglycaemia (<2.2mM) = ‘stress’ Insulin-induced hypoglycaemia stimulates GH release ACTH release (cortisol measured) TRH stimulates TSH release GnRH stimulates FSH & LH release So these would stay low in a patient with hypopituitarism.
What is an empty sella?
no discernible pituitary tissue
What is the treatment for Growth hormone?
Easier to determine in children harder in adults.
NICE guidance:
Confirm GH deficiency on dynamic pituitary function test
Assess Quality of Life (QoL) using specific questionnaire
Daily injection if low QoL
Measure response by
improvement in QoL
plasma IGF-1 - GH tells liver to make IGF-1.
Why is the posterior pituitary not affected in Sheehan’s syndrome?
Origin is neural, not dependent on blood supply.
