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Endocrinology 2 > Hypopituitarism > Flashcards

Hypopituitarism Flashcards

1
Q

What are the 5 types of hormones the anterior pituitary produces?

A 
Somatotrophs produce growth hormone
Lactotrophs produce prolactin.
Gonadotrophs produce FSH and LH. 
Corticotrophs produce ACTH. 
Thyrotrophs produce TSH.
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2
Q

What is the role of hypothalamo-pituitary portal system?

A

Hypothalamic releasing or inhibitory factors travel in the portal circulation to the anterior pituitary to regulate anterior pituitary hormone production.

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3
Q

What are the roles of the anterior pituitary hormones?

A

GH is responsible for growth. Prolactin causes milk production. FSH and LH act on the ovaries and testes to produce oestrogen, progesterone and testosterone. TSH leads to production of triiodothyronine and thyroxine. ACTH stimulates cortisol production.

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4
Q

What is anterior pituitary failure?

A

When the thyroid, adrenal cortex or gonads fail to produce hormones, this can be due to a primary failure of the organ itself or a secondary failure of the anterior pituitary/hypothalamus resulting in a lack of stimulating hormone.

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5
Q

Compare primary vs secondary hypothyroidism

A

Primary hypothyroidism is caused by a failure of the thyroid due to autoimmune destruction of thyroid gland. T3 & T4 fall, TSH increases (we don’t measure TRH but that would also be high) due to lack of negative feedback. Secondary hypothyroidism is caused by e.g. eg pituitary tumour damaging thyrotrophs. TSH is not made, T3 and T4 are also low.

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6
Q

Compare primary vs secondary hypoadrenalism

A

Primary hypoadrenalism is caused by a failure of the adrenal gland due to e.g. destruction of adrenal cortex (eg autoimmune). Cortisol falls but ACTH increases due to no negative feedback. Secondary hypoadrenalism is caused by eg pituitary tumour damaging corticotrophs. Here, no ACTH is made and so low cortisol.

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7
Q

Compare primary vs secondary hypogonadism

A

Primary hypogonadism is caused by a failure of the gonads due to eg destruction of testes (eg mumps) or ovaries (eg chemotherapy). Testosterone and Oestrogen remain low while FSH and LH are elevated. In secondary hypogonadism, FSH and LH are also low. This can be caused by a pituitary tumour.

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8
Q

What are the congenital causes of hypopituitarism?

A

It is usually due to mutations of transcription factor genes needed for normal anterior pituitary development e.g. PROP1 mutation. It is defined by a deficiency in GH and at least one other anterior pituitary hormone.

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9
Q

What is the presentation of congenital hypopituitarism?

A

Is rare. Short stature, hypoplastic AP on MRI.

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10
Q

What are the causes of acquired hypopituitarism?

A

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)
TIPP TRIP
Tumour, Infection, Pit surgery, Pit apop, Trauma, Radiation, Inflamm, Peripar

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11
Q

What are the different types of hypopituitarism?

A

May affect one axis or several within anterior pituitary. Surgery/Hypophysitis may also cause posterior pituitary dysfunction so if both affected, named panhypopituitarism.

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12
Q

What is radiotherapy induced hypopituitarism?

A

Pituitary and hypothalamus are both sensitive to radiation. Radiotherapy may be direct to pituitary eg acromegaly or indirect eg nasopharyngeal carcinoma. Gonadotrophs are the most vulnerable and loss of hypothalamic dopamine can mean increase in prolactin after therapy. Extent of damage depends on dose and effects can show up to 10 years after therapy so an annual assessment is required.

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13
Q

What are the presentations of hypopituitarism?

A 
FSH/LH
	Reduced libido
	Secondary amenorrhoea
	Erectile dysfunction
	Reduced pubic hair
ACTH	
	Fatigue
	NB Not a salt losing crisis (renin-	angiotensin)
TSH					
	Fatigue
GH
	Reduced quality of life
	NB short stature only in children
PRL	
	Inability to breastfeed
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14
Q

What is Sheehan’s syndrome?

A

Post-partum hypopituitarism secondary to hypotension (post partum haemorrhage - PPH). Blood loss during delivery can cause hypotension and anterior pituitary enlargement due to lactotroph hyperplasia is common during pregnancy. Therefore, PPH leads to pituitary infarction. This is more common in developing countries. Posterior pituitary usually not affected.

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15
Q

What are the symptoms of Sheehan’s syndrome?

A

Lethargy, anorexia, weight loss due to TSH/ACTH/(GH) deficiency.
Failure of lactation – PRL deficiency
Failure to resume menses post-delivery

LAW Lactation

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16
Q

What is pituitary apoplexy?

A

It is intra-pituitary haemorrhage or (less commonly) infarction. There is often a dramatic presentation in patients with pre-existing pituitary tumours (adenomas) and it may be the first presentation of a pituitary adenoma. Can be precipitated by anti-coagulants.

17
Q

What are the symptoms of pituitary apoplexy?

A

Severe sudden onset headache
Visual field defect – compressed optic chiasm causing bitemporal hemianopia
Cavernous sinus involvement may lead to cranial nerve compression causing diplopia (IV, VI), ptosis (III)

18
Q

What is important to consider when doing a biochemical diagnosis of hypopituitarism?

A

Cortisol – what time of day measurement is taken as highest at 8am, diurnal rhythm
T4 – circulating t1/2 6 days
FSH/LH – cyclical in women during menstrual cycle
GH/ACTH - pulsatile release

19
Q

How is hypopituitarism diagnosed?

A

ACTH and GH are stress hormones and so levels measured by inducing stress. Insulin-induced hypoglycaemia (<2.2mM) causes GH release and ACTH release, leading to increase in cortisol which is measured.
TRH given to stimulate TSH.
GnRH given to stimulate FSH and LH.

20
Q

What choice of radiology is used to screen pituitary gland?

A

MRI as CT not good at delineating pituitary gland. MRI may reveal specific pituitary pathology eg haemorrhage (apoplexy), adenoma. Empty sella occurs when there is only a thin rim of pituitary tissue.

21
Q

How is GH deficiency treated?

A

If reported as low based on dynamic pituitary function test, must fill out an assessment of QoL form to check whether they need replacement or not as can play a role in psychological wellbeing. If required, a daily injection provided and progress checked based on IGF-1 levels and improvement in QoL.

22
Q

How is TSH deficiency treated?

A

Levothyroxine 100mg prescribed for once a day. TSH will be low so cannot be used as an indicator to adjust dose. Aim for a fT4 above the middle of the reference range.

23
Q

How is ACTH deficiency treated?

A

Cortisol is replaced but difficult to maintain diurnal rhythm. Either 3mg prednisolone daily AM prescribed or hydrocortisone (10-5-5mg) prescribed. Both are synthetic glucocorticoids.

24
Q

What do those with ACTH deficiency need to be aware of when ill?

A

Intercurrent illness can trigger adrenal crisis (also in those with Addison’s) so must do 3 things:

  1. Wear a steroid alert pendant/bracelet
  2. Double steroid dose (glucocorticoid not mineralocorticoid) if fever/intercurrent illness
  3. If unable to take tablets (eg vomiting), inject IM or come straight to A & E
25
Q

What are the symptoms of an adrenal crisis?

A

Dizziness, hypotension, vomiting, weakness, can result in collapse and death

26
Q

How is FSH/LH deficiency treated in men?

A

If fertility is not required:
IM injection or topical replacement of testosterone provided. Plasma testosterone measured. FSH needed for sperm production so only testosterone will not cause fertility.

If fertility required:
Gonadotrophin injections given to prompt spermatogenesis. Works best if S. hypogonadism has occured after puberty. Sperm prod may take 6-12 months but plasma and semen analysis done to measure hormone levels.

27
Q

How is FSH/LH deficiency treated in women?

A

If fertility not required:
Oral/topical oestrogen plus progesterone if uterine lining intact to avoid endometrial hyperplasia.

If fertility required:
Timed gonadotrophin injections can induce ovulation.

Endocrinology 2 (11 decks)

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