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Yr3 Medicine- Endocrinology > Pituitary Pathology > Flashcards

Pituitary Pathology Flashcards

1
Q

Remind yourself what is found:

  • Superior to pituitary
  • Lateral to pituitary
A
  • Superior: optic chiasm
  • Lateral: cavernous sinus
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2
Q

State the 7 hormones released from the hypothalamus

A
  • TRH
  • CRH
  • GnRH
  • GHiH
  • GHrH
  • PIH
  • PRH
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3
Q

State the 6 hormones released by the anterior pituitary

A
  • TSH
  • GH
  • Prolactin
  • LH
  • FSH
  • ACTH
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4
Q

State the 5 pituitary axes

A
  • Growth axis
  • Adrenal axis
  • Gonadal axis
  • Thyroid axis
  • Prolactin axis
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5
Q

For the growth axis, describe:

  • Secretion of GH
  • What organs GH acts on and what its effects are
A
  • Pulsatile rlease with peak pulses in REM sleep
  • GH acts on liver to produce insulin like growth factors (1). GH acts directly on its receptor as well as via IGF1.
    • Children: musculoskeletal growth
    • Adults: maintain muscle & bone mass, promote healing & repair, modulate metabolism & body composition
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6
Q

For the adrenal axis, describe:

  • Circadian rhythm
A
  • Peak pulses in early morning, lowest activity at midnight
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7
Q

For the gonadal axis, describe:

  • Actions of FSH in men & women
  • Actions of LH in men & women
  • Pattern of release of GnRH
  • Effect of prolactin on gonadal axis
A
  • FSH
    • Men: sperm production
    • Women: ovarain follicle development
  • LH
    • Men: testosterone secretion from Leydig cells
    • Women: LH surge causes mid cycle ovulation and formation of corpus luteum
  • GnRH is released in pulsatile fashion
  • Prolactin inhibits GnRH secretion and hence inhibits FSH & LH secretion
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8
Q

For the thyroid axis, describe:

  • TRH effect on prolactin
A
  • TRH is a weak stimultor of prolactin secretion
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9
Q

For the prolactin axis, describe:

  • Effects of prolactin on LH and FSH
  • Which hormone mainly controls prolactin levels
A
  • Prolactin inhhibits GnRH release and hence inhibits LH and FSH
  • Predominatly under negative control by dopamine and weak stimulating control by TRH
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10
Q

Pituitary tumours can present in two ways; describe each

A

Present as:

  • Compression of surrounding structures
  • Effects of hormone excess or deficiency (dependent on whether it is a functioning or non-functioning pituitary rumour)
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11
Q

What is meant by a functioning pituitary tumour?

What is meant by a non-functioning pituitary tumour?

A
  • Functioning: producing pituitary hormones
  • Non-functioning: not producing pituitary hormones
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12
Q

Non functioning pituitary tumours can present wtih hypopituitarism. In hypopituitarims what usually happens to the levels of the hormones produced by the pituitary?

A

In hypopituitarism usually all hormones decrease apart from prolactin (which increased eu to disinhibition prolactinaemia- if tumour is compressing pituitary stalk then less dopamine can reach pituitary and hence less inhibition of prolactin release)

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13
Q

We have said that pituitary tumours can present with symptoms of compression of surrounding structures; what structures could be compressed and what would this present with?

A

Optic chiasm: decreased visual acuity and bitempoarl hemianopia

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14
Q

We can measure levels of pituitary hormones, and the downstream hormones of the axis, to determine pituitary function. For each of the following, describe when they should be tested:

  • Prolactin
  • TSH & T4
  • LH & FSH
  • Testosterone
  • Cortisol
  • IGF-1
A
  • Prolactin can be measured any time of day
  • TSH & T4 can be measured any time of day. Must check both T4 and TSH as TSH can be normal in secondary hypothyroidism
  • LH & FSH:
    • Women: within 1st 5 days menstrual cycle
    • Men: LH, FSH & testosterone at 9:00 in fasting state
  • Cortisol: early morning (if you suspect it to be low)
  • IGF-1 measure any time
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15
Q

Describe the insulin tolerance test; include what is done and how it works/what it measures

Which pts should the insulin tolerance test NOT BE performed in?

A
  • Give IV insulin to induce hypoglycaemia (<2.2mmol/L). Under normal conditions, body will release ACTH and GH from pituitary
  • DO NOT do in pts with ischaemic heart disease or epilepsy as risk of coronary ischaemia or ischaemia
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16
Q

What is the imaging modality of choice for the pituitary?

A

MRI

NOTE: can use contrast to highlight differnce between tumour and normal gland. CT may be adequete in pts who cannot have MRI. There is an increasing interest in functional imaging of pituitary tumours (PET and fMRI) to determine functionality of lesion

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17
Q

We can class pituitary tumours as macro- and micro- adenomas; state size of each

A
  • Macroadenoma= >1cm
  • Microadenoma= <1cm
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18
Q

Which is more common: micro- or macro- prolactinoma?

A

Micro-prolactinoma

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19
Q

High prolactin levels are common in clincial practice; true or false?

A

True

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20
Q

State some potential causes of high prolactin levels

A
  • Pregnancy
  • Medications e.g. anti-emetics, anti-psychotics
  • PCOS can cause mild hyperprolactinaemia
  • Profound hypothyroidism (rare)
  • Prolactinoma (micro- or macro-)
21
Q

Discuss how you could distinguish between micro-prolactinoma and PCOS

A
  • PCOS will have lower prolactin levels than micro-prolactinoma and will have no findings on MRI
  • Micro-prolactionma will not have androgenergic symtpoms
22
Q

State some symptoms of hyperprolactinaemia

A

Women

  • Oligomenorrhoea or amenorrhoea
  • Infertility
  • Galactorrhoea
  • Decreased libido
  • Weight gain
  • Vaginal dryness

Men

  • Erectile dysfunction
  • Decreaed facial hair
  • Galactorrhoea
23
Q

Discus what investigations you would do if you find a pt has hyperprolactinaemia

*HINT: to help, think about the potential causes of hyperprolactinaemia and how you would want to rule those out

A
  • Pregnancy test
  • TFTs
  • U&Es
  • MRI pituitary
24
Q

Discuss the treatment of hyperprolactinaemia

A
  • Dopamine (D2) agonissts e.g. cabergoline or bromocriptine **Cabergoline= better tolerated. Remember dopamine is prolactin inhibiting hormone
  • NOTE: even large macroprolactinomas are treated medically. Medical treatment usually results in good reduction in prolactin & tumour bulk*
25
Q

State some common side effects of dopamine (D2) agonists

A
  • Nasea
  • Postural hypotension
  • Psychiatric disturbance (rare)
26
Q

In 15% of macroprolactinomas, rapid reduction in size of lesion can result in…?

A

CSF leak which has potential risk of meningitis

27
Q

Discuss whether each of the following is more common in men or women:

  • Micro-prolactinoma
  • Macro-prolactinoma
A
  • Micro-prolactinoma: women
  • Macro-prolactinoma: men
28
Q

What is acromegaly?

A

Excessive growth hormone

29
Q

What causes acromegaly?

A

Almost exclusively caused by GH-secreting pituitary tumour

30
Q

State the signs & symptoms of acromegaly

A

Symptoms

  • Fatigue
  • Headaches
  • Increased appetite
  • Snoring
  • Sexual dysfunction e.g. decreased libido, erecetile dysfunction, oligomenorrhoea, amenorrhoea
  • Sweating

Signs

  • Increased size of hands & feet
  • Facial features: frontal bossing, protrusion of chin, jaw enlargement -> widely spaced teeth
  • Soft tissue swelling: macroglossia (snoring & sleep apnoea), carpal tunnel syndrome
  • Diabetes mellitus: polyuria, polydipsia, glucosuria
31
Q

What investigations would you do if you suspect acromegaly?

A
  • Plasma insulin like growth factor 1 (IGF-1)= initial screening test
  • Oral glucose tolerance test (OGTT): if GH is not supressed after OGTT it indicates acromegaly
  • Pituitary MRI
  • Refer to opthalmology for visual field testing

NOTE: can measure serum GH but it is not very reliable as GH secretion is pulsatile and is increased by other factors such as stress, sleep, puberty, pregnancy etc….

32
Q

Discuss the treatment for acromegaly

A
  • Surgery to remove tumour (remission is more likely in microadenomas than in macroadenomas)
  • Medical treatment:
    • Somatostatin analogues to block GH release e.g. ocreotide
    • GH receptor antagonist e.g. pegvisomant
    • Dopamine agonists to block GH release e.g. bromocriptine
  • Radiotherapy

*NOTE: dopamine has an inhibitory effect on GH release, however not as potent as somatostatin

33
Q

State some negatives regarding radiotherapy as treatment for acromegaly

A
  • May take years to lower GH
  • Long term use may lead to gradual onset hypopituitarism, CVD
34
Q

Discuss the long term monitoring of pts with acromegaly

A
  • After initial surgery, OGTT to see if persistent disease
  • Regular, long term follow up of GH & IGF-1 to see if reoccurence
  • Periodic colonscopy
  • Assess intermittently for:
    • Cardiac disease
    • Sleep apnoea
    • Diabetes
35
Q

Discuss potential complications of acromegaly

A
  • Cardiac disease: valvular heart disease, LVH, ischaemic heart disease, arrhythmia, cardiomyopathy
  • Hypertension
  • Pre-cancerous colon polyps (increase risk colon cancer)
  • Sleep apnoea
  • Diabetes
  • Carpal tunnel syndrome
  • Treatment related hypopitutarism
36
Q

As we have already said before, non-functioning pituitary adenomas are biochemically inactive tumours. Describe how they usaully present

A
  • Visual field loss
  • Headache
  • Hypopituitarism
37
Q

Discuss the treatment for non-functioning pituitary adenomas

A

Surgery is indicated if there is visual defect or threat to vision

Route= usually transphenoidal

38
Q

Histologically NFPAs have +ve immuno-staining for biologically inactive….?

A

LH & FSH

39
Q

What is meant by hypopituitarism?

What is panhypopituitarism?

A
  • Deficiency in one or more of pituitary hormones
  • Deficiency in all of pituitary hormones
40
Q

State some potential causes of hypopituitarism

**HINT: think of the causes at 3 different levels: hypothalamus, pituitary stalk, pituitary

A

Hypothalamus

  • Kallman’s syndrome
  • Tumour
  • Inflammation
  • Infection e.g. meningitis
  • Ischaemia

Pituitary stalk

  • Trauma
  • Surgery
  • Mass

Pituitary

  • tumour
  • Autoimmunity
  • Infiltration e.g. haemochromatosis
  • Ischaemia e.g. Sheehan’s syndrome
41
Q

State the order in which hormones are affected in hypopituitarism

A
  1. GH
  2. LH & FSH
  3. TSH
  4. ACTH
  5. PRL
42
Q

Discuss the presentation of hypopituitarism

A

Often causes non-specific symptoms such as lethargy, weight gain, sexual dysfunction etc… But may also cause symptoms specific to hormone deficiency e.g.:

  • GH: decreased growth children, decreaed muscle & bone mass/decreased wound healing/altered metabolism & body composition
  • TSH: hypothyroidism
  • PRL: absent lactation
  • LH & FSH: oligmenorrhea, amenorrhoea, decreased fertility, decreased libido, breast atrophy, erectile dysfunction, hypogonadism
  • ACTH: adrenal insufficiency
43
Q

Hypopituitarism may present as an acute hypoadrenal crisis with hyponatraemia and hypertension; true or false?

A

True

44
Q

Discuss the investigations for hypopituitarism

A
  • Basal tests of pitutary hormones
  • Dynamic tests: synacthen, insulin tolderance test
  • MRI scan
45
Q

Discuss the treatment of hypopituitarism, include treatment for:

  • ACTH deficiency
  • TSH deficiency
  • Gonadotrophin deficiency
  • Growth hormone deficiency
A
  • ACTH deficiency
    • Hydrocortisone
  • TSH deficiency
    • Levothyroxine
  • Gonadotrophin deficiency
    • Men: testosterone replacement (gel or injection)
    • Women: oestrogen & progesterone replacement (COCP or HRT)
  • Growth hormone deficiency
    • Replacement GH via daily sc injection
46
Q

What is a hypopituitary coma?

A

Acute hypopituitary crisis; could be decompensation of chronic hypopituitarism or due to pituitary infarction (e.g. in Sheehan’s syndrome)

47
Q

Describe presentation of hypopituitary coma

A
  • Hypotension
  • Hypothermia
  • Hypoglycaemia
  • Headache
  • Ophthalmoplegia
  • Decreased consciousness/GCS
  • Signs of hypopituitarism (if chronic) e.g. loss of axillary and pubic hair, short stature
48
Q

What investigations would you do for hypopituitary coma?

A

DON’T wait for investigations as this can be fatal; start treatment if you suspect but investigations you would do include:

  • VBG (glucose)
  • Cortisol
  • ACTH
  • TFTs
  • FBC
  • U&Es
  • LFTs
  • Pituitary fossa CT or MRI
49
Q

Discuss the management of hypopituitary coma

A
  • IV hydrocortisone
  • IV liothyronine (after hydrocortisone)
  • Fluids
  • Correction of hypoglycaemia

Definitive management may include surgery

Yr3 Medicine- Endocrinology (9 decks)

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