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BRS - Year 2 > 🧪Endocrinology🧪 - Hypopituitarism > Flashcards

🧪Endocrinology🧪 - Hypopituitarism Flashcards

1
Q

Name the hormones produced by the pituitary gland

A

Growth hormone (somatotrophin)
Prolactin
TSH
LH, FSH
ACTH (corticotrophin)

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2
Q

Name the circulation in the anterior pituitary, and its constituent parts

A

Hypophyseal portal circulation
Primary capillary plexus (located in the median eminence)
Hypophyseal portal veins
Secondary capillary plexus

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3
Q

Briefly explain the hypothalamo-pituitary portal

A

Hypothalamic releasing or inhibitory factors (named after the fact they are released in the hypothalamus) travel via the portal circulation to the anterior pituitary to regulate hormone production of the ANTERIOR pituitary

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4
Q

What are the functions of the anterior pituitary hormones?

A

GH - growth of soft tissue (and bones before fusion of the epiphyseal plate)
Prolactin - milk production
FSH and LH - production of sex hormones
TSH - stimulation of thyroid hormones
ACTH - stimulation of cortisol release

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5
Q

Most common PRESENTING forms of anterior pituitary failure?

A

Thyroid hormones
Adrenal cortex (cortisol)
Gonad failure

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6
Q

Explain the difference between primary and secondary failure of glands? (Thyroid, adrenals, gonads)

A

Primary disease is failure of the gland itself (i.e. autoimmune damage, trauma etc….)

Secondary disease is failure of signals due to hypothalamic or pituitary damage

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7
Q

What is the most common form of hypothyroidism?

A

Primary hypothyroidism, particularly due to autoimmune destruction

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8
Q

What is primary vs secondary hypothyroidism?

A

Primary due to destruction of the gland (usually autoimmune damage)
Secondary due to pituitary tumour damaging thyrotrophs

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9
Q

What are the differences in hormone levels between primary and secondary hypothyroidism?

A

Primary sees T3 and T4 falling, and TSH increasing

Secondary sees T3, T4 and TSH falling

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10
Q

Explain the difference in TSH levels in primary and secondary hypothyroidism?

A

In primary, TSH increases as the negative feedback system is still intact, so the** lack of T3/T4 stimulates TSH release** in pituitary.

In secondary, the pituitary is damaged and so the negative feedback system is nonfunctional, as TSH is unable to be produced

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11
Q

Primary vs secondary hypoadrenalism?

A

Primary features the destruction of the adrenal cortex itself.

Secondary features a pituitary tumour that damages corticotrophs

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12
Q

What are the differences in hormones between primary and secondary hypoadrenalism?

A

Primary has low cortisol and high ACTH

Secondary has low cortisol and low ACTH

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13
Q

Explain the differences in ACTH levels between primary and secondary hypoadrenalism

A

Primary has high ACTH, as adrenal cortex is damaged not pituitary, so negative feedback loop is intact, leading to increased ACTH production due to lack of cortisol as corticotrophs are undamaged

Secondary has low ACTH as corticotrophs are damaged, so no ACTH production and a non functional negative feedback loop

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14
Q

Primary vs secondary hypogonadism

A

Primary is destruction of testes or ovaries, leading to low testosterone or oestrogen, but high LH and FSH

Secondary is pituitary damage affecting gonadotrophs, so LH/FSH can not be made. LH and FSH fall.
Testosterone/oestrogen also fall

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15
Q

What is the most common cause of hypopituitarism? (Congenital vs acquired)

A

Acquired much more common

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16
Q

How does congenital hypopituitarism arise?

A

Usually due to mutations of transcription factor genes needed for normal anterior pituitary development (e.g. PROP1 mutation)

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17
Q

How does congenital hypopituitarism present?

A

Deficient in GH and at least 1 other anterior pituitary hormone
Short stature
Hypoplastic anterior pituitary gland (visible on an MRI)

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18
Q

What are the causes of acquired hypopituitarism?

A

Tumours(e.g. adenomas, metastases, cycsts)
Radiation (damage to either pituitary or hypothalamus)
Infection (e.g. meningitis)
Trauma
Pituitary surgery
Inflammation (hypophysitis)
Pituitary apoplexy (haemorrhage)
Sheehan’s syndrome (peri-partum infarction)

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19
Q

What does hypopituitarism affect?

A

Can affect one axis, several or all
Often describes anterior pituitary but some forms can cause posterior pituitary damage as well

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20
Q

What is panhypopituitarism?

A

Total loss of anterior and posterior pituitary function

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21
Q

What is the term for total loss of all pituitary function?

A

Panhypopituitarism

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22
Q

Which pituitary hormones are most sensitive to radiation?

A

GH and gonadotrophins (LH/FSH)

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23
Q

What are the associated risks with the pituitary gland, re radiotherapy?

A

GH and gonadotrophins (LH/FSH) affected
Risk of damage persists for up to 10 years, so annual assessments needed

24
Q

How does hypopituitarism affecting LH/FSH production present?

A

Reduced libido
(Secondary) amenorrhoea
Erectile dysfunction
Reduced pubic hair

25
Q

How does hypopituitarism affecting ACTH production present?

A

Fatigue

26
Q

How does hypopituitarism affecting prolactin production present?

A

Inability to breastfeed
Asymptomatic in anyone other than recent mothers

27
Q

How does hypopituitarism affecting growth hormone production present?

A

Reduced quality of life (decreased muscle mass and endurance, decreased bone density, wide range of other symptoms attributing to a lower quality of life)
Short stature only in children

28
Q

Why does low growth hormone production only cause short stature with congenital hypopituitarism or hypopituitarism acquired during childhood?

A

Growth hormone only used for growth and height in children, before epiphyseal plates have fused. Adults have already finished growing

29
Q

Why do cases of hypopituitarism causing prolactin deficiency often go unnoticed?

A

Asymptomatic in all members of the population apart from mothers attempting to breastfeed, due to prolactin having limited significant role in other body processes

30
Q

What is Sheehan’s syndrome?

A

Post-partum pituitary infarction due to post-partum haemorrhage (PPH) and subsequent hypotension

31
Q

How does Sheehan’s syndrome present?

A

Lethargy, anorexia, weight loss - TSH/ACTH/GH deficiencies
Failure to lactate - prolactin deficiency, significant as this effects new mothers
Failure to resume menses post delivery - gonadotrophin deficiency
Posterior pituitary usually unaffected

32
Q

What other diagnoses can be considered in a patient presenting with Sheehan’s syndrome-like symptoms?(4)

A

Primary thyroiditis (autoimmune destruction)
Post-partum depression
Anaemia
Pituitary apoplexy

33
Q

Why is primary thyroiditis quite common post-partum?

A

Reactivation of immune system post-partum can lead to autoimmune conditions
Immune system is “jump-started”

34
Q

How might pituitary apoplexy occur (especially in a new mother)?

A

Pituitary gland vulnerable to haemorrhaging from gestational hypertension
Normal physiology of pregnancy has lactotroph hyperplasia, more susceptible to haemorrhages

35
Q

What symptoms might pituitary apoplexy present with that could immediately distinguish it from Sheehan’s syndrome, and why they occur?

A

Visual field defects such as bitemporal hemianopia, due to compressed optic chiasm
Diplopia(IV, VI) or ptosis(III) due to cavernous sinus involvement

36
Q

How might pituitary apoplexy present?

A

Severe sudden onset headache
Visual field defect
Ptosis(III)
Diplopia(IV, VI)

37
Q

What are some causes of pituitary apoplexy?

A

Haemorrhage into pituitary gland, often in patients with pre-existing adenomas
May be the first presentation of an adenoma
Can be precipitated by anti-coagulants

38
Q

What are the problems with measuring the basal plasma concentrations of hormones as a means of diagnosing hypopituitarism?

A

Cortisol - can only be measured in the morning
T4 - very long circulating time
FSH/LH - cyclical in women
GH/ACTH - pulsatile

39
Q

What investigation is used to diagnose hypopituitarism?

A

Dynamic pituitary function test

40
Q

Describe the investigation for hypopituitarism

A

An injection of insulin is given to induce hypoglycaemia (<2.2mM) = “stress”
At the same time, TRH and GnRH is injected
Insulin induced hypoglycaemia stimulates GH release and ACTH release (cortisol is measured)
TRH stimulates TSH release
GnRH stimulates FSH/LH release

41
Q

Which groups of patients are unable to take the dynamic pituitary function test?

A

Elderly people, people with epilepsy, people with heart conditions

42
Q

What imaging is used for investigations of the pituitary gland?

A

MRI (magnetic resonance imaging)

43
Q

What is the only hormone that cannot be replaced in hypopituitarism?

A

Prolactin

44
Q

Outline the steps for treating GH deficiency

A

Confirm GH deficiency on dynamic pituitary function test (specifically with insulin-induced hypoglycaemia)
Assess quality of life using specific QoL questionnaire
Daily injection

45
Q

Why can GH deficiency not be treated orally?

A

The treatment consists of peptide hormones which would be broken down in the stomach

46
Q

How is the response to GH treatment measured?

A

Improvement in quality of life
Increased plasma IGF-1

47
Q

Outline the steps for treating TSH deficiency

A

Replace with once daily levothyroxine
TSH will be low as negative feedback system is non-functional, so TSH levels cannot be used to adjust dose such as in primary hypothyroidism
Aim for a T4 range above the middle of the reference range

48
Q

Outline the steps for treating ACTH deficiency

A

Replace cortisol instead of ACTH
Give synthetic glucocorticoids
Options:
Prednisolone once daily (e.g. 3mg)
Hydrocortisone 3x daily (e.g. 10/5/5mg)

49
Q

Which patients are more at risk of an “adrenal crisis”?

A

Patients with primary adrenal failure (Addison’s) or secondary adrenal failure (ACTH deficiency)

50
Q

What do adrenal crises commonly feature?

A

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

51
Q

What are the “sick day rules” for patients at risk of adrenal crises?

A

Steroid alert pendant/bracelet
Double glucocorticoid dose if fever/intercurrent illness
If unable to take tablets(e.g. vomiting, unconscious etc…), inject intramuscularly (IM) and straight to A&E

52
Q

How is FSH/LH deficiency treated in men where fertility is NOT required?

A

Replace testosterone
Topical or IM most popular methods
Measure plasma testosterone

53
Q

Why does replacing testosterone not result in fertility in men?

A

Replacing testosterone does not result in spermatogenesis, this requires LSH and FH

54
Q

How is FSH/LH deficiency treated in men where fertility is REQUIRED?(4)

A

Induction of spermatogenesis by gonadotropin injections
Best response if secondary hypogonadism has developed after puberty
Measure testosterone, semen analysis
Sperm production may take 6-12 months

55
Q

How is FSH/LH deficiency treated in women where fertility is NOT required?(3)

A

Replace oestrogen
Oral or topical
Needs additional progesterone to prevent endometrial hyperplasia

56
Q

How is fertility induced in women with FSH/LH deficiency?

A

Carefully timed gonadotropin injections
IVF

57
Q

Why is progesterone given to women with FSH/LH deficiency even when fertility is NOT required?

A

To induce shedding of uteral lining
Uteral lining should be shed 3-4 times per year minimum so as to prevent endometrial hyperplasia, which can lead to endometrial cancer

BRS - Year 2 (46 decks)

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