Hypopituitarism Flashcards
What are the 6 hormones released by the anterior pituitary gland?
- Prolactin
- Growth hormone (somatotrophin)
- Thyroid Stimulating Hormone (TSH)
- Luteinising Hormone (LH)
- Follicle Stimulating Hormone (FSH)
- Adrenocorticotrophic Hormone (ACTH)
What does prolactin stimulate?
Milk production
What does LH and FSH stimulate?
- Oestrogen
- Progesterone
What does TSH stimulate?
Triiodothyronine (T3) - active
Thyroxine (T4)
What does ACTH stimulate?
Cortisol release
What is the difference between primary and secondary pituitary gland failure?
Primary: failure of the gland itself
Secondary: no signals from the hypothalamus or the anterior pituitary
What is characteristic of primary hypothyroidism?
thyroid destruction
- T3 and T4 fall
- TSH increases (unmeasured but TRH would also be high)
What is characteristic of secondary hypothyroidism?
damaged thyrotrophs
- TSH falls
- T3 and T4 fall without TSH
What is characteristic of primary hypoadrenalism?
adrenal cortex destruction
- cortisol falls
- ACTH increases (CRH would be high)
What is a characteristic of secondary hypoadrenalism?
corticotroph damage
- ACTH falls
- Cortisol falls
What is characteristic of primary hypogonadism?
Destruction of testes (mumps) or ovaries (chemo)
- Testosterone / estrogen fall
- LH and FSH increase
What is characteristic of secondary hypogonadism?
- damaged gonadotrophs
- LH and FSH fall (can’t be produced)
- Testosterone / estrogen fall
Causes of Hypopituitarism?
- Congenital (rare)
- Acquired
What are the congenital cause of hypopituitarism?
- Due to mutations of transcription factor genes needed for normal development
- Deficient in GH and at least one more anterior pituitary hormone
- Short stature
- Hypoplastic anterior pituitary gland (MRI)
What are the acquired causes of hypopituitarism?
- tumours
- radiation
- infection
- traumatic brain injury
- pituitary brain surgery
- inflammation
- pituitary apoplexy (haemorrhage or infarction)
- peri-partum infection (Sheehan’s syndrome)
What can cause anterior and posterior pituitary gland dysfunction?
- inflammation (hypophysitis)
- surgery
What is the term for the total loss of anterior and posterior pituitary function?
Panhypopituitarism
Impact of radiotherapy on hypopituitarism?
- damage to pituitary gland and hypothalamus causing hypopituaitarism
- extent depends on the total dose of radiotherapy delivered to the hypothalamo-pituitary axis
- GH and gonadotropins are most sensitive
- prolactin can increase after radiotherapy (loss of hypothalamic dopamine)
- risk persists up to 10years after radiotherapy (annual assessment necessary)
How does hypopituitarism with low LH/FSH present?
- reduced libido
- secondary amenorrhoea
- erectile dysfunction
- reduced pubic hair
How does hypopituitarism with reduced ACTH present?
- fatigue
- not a salt losing crisis (renin-angiotensin is regulated by aldosterone)
How does reduced TSH due to hypopituitarism present?
fatigue
How does reduced GH (hypopituitarism) present?
- reduced quality of life
- short stature only in children
How does reduced prolactin present?
inability to breastfeed
What is Sheehan’s syndrome?
Post-partum hypopituitarism secondary to severe hypotension (caused by post-partum haemorrhage, which can lead to a pituitary infarction)
