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MET3B > Pituitary diseases and Acromegaly > Flashcards

Pituitary diseases and Acromegaly Flashcards

1
Q

Where in the skull does the pituitary sit?

A

Rests in the sella turcica,

below the optic chiasm

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2
Q

Which hormones are produced by the anterior glad of the pituitary?

A 
ACTH - Adrenal cortex 
 TSH - Thyroid gland 
 GH - Bone 
 LH, FSH - testes and ovaries
 PRL- mammary glands
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3
Q

Which hormones are released from the posterior pituitary?

A 
vasopressin - act in kidney tubules 
oxytocin - acts on muscle in uterus 
released
directly from neurons in
the hypothalamus:
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4
Q

What is the blood supply for the anterior and posterior pituitary gland?

A

Anterior
- capillary plexus

Posterior pituitary 
- inferior
hypophyseal artery and
drains into the inferior
hypophyseal veins – going
directly into the systemic
circulation
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5
Q

Which conditions are presented clinically with a pituitary adenoma?

A

Prolactinoma - amenorrhoea / galactorrhoea
Acromegaly
Cushing’s Disease
(Thyrotoxicosis – secondary)

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6
Q

Which symptoms of mass effect are associated with pituitary adenomas?

A

Headaches

Vision loss

Pituitary gland hyposecretion (hypopituitarism)

Pituitary apoplexy

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7
Q

What is Most common functioning pituitary adenoma?

A

Prolactinoma

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8
Q

What are the signs and symptoms of Prolactinoma?

A 
Symptoms 
- Amemorrhoea, 
- galactorrhoea,
 - erectile dysfunction, If very
large can lead to sight loss –
chiasmal compression
-

Signs
Galactorrhoea, hypogonadism,
bitemporal hemianopia

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9
Q

Which investigations are conducted for a prolactinoma?

A

Prolactin, TFT, LH, FSH,

Testostorone, MRI pituitary

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10
Q

How is a prolactinoma treated?

A

treated with dopamine agonists
(dopamine causes tonic
inhibition of prl release) –
bromocriptine / cabergoline

Surgery for non responsive adenomas of when there is significant compressive effects

Radio therapy for when drugs and surgery are ineffective

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11
Q

Which visual field defect is caused by prolactinoma?

A

Bitemporal hemianopia

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12
Q

Apart from a prolactinoma, what else can cause a high amount of prolactin?

A 
Lactation/Pregnancy
Drugs:

 Antacids (ranitidine)

 Anti-psychotics (chlorpromazine)

 Anti-emetics (prochlorperazine)

Stress
Seizures
Stalk compression
Macroprolactin

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13
Q

How is prolactinoma diagnosed?

A

Prolactin >100 ng/mL suggests probable pituitary adenoma

A basal, fasting, morning PRL >100−200 mg/L (normal <20 mg/L) in a nonpregnant
woman indicates a need for a pituitary MRI.

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14
Q

What is the cause of acromegaly?

A

excess of growth hormone

most commonly related to a pituitary adenoma.

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15
Q

Which cells release growth hormones?

A

somatotropic cells within the anterior pituitary.

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16
Q

Describe the normal physiology of growth hormone production

A

Growth hormone releasing hormone (GHRH) is released from the arcuate nucleus of the hypothalamus.

It is transported via the hypophyseal portal system to the anterior pituitary. Here it stimulates the release of growth hormone.

Growth hormone (GH) is released from the somatotropic cells of the anterior pituitary

It stimulates the release of insulin-like growth factor -1 (IGF-1).

IGF-1 is produced and released by the liver.

IGF-1 and GH release leads to the inhibition of GHRH and stimulation of somatostatin release.

17
Q

Where in the body is insulin-like growth factor -1 (IGF-1) produced and released?

A

By the liver

18
Q

Which hormone is the negative regulator if growth hormone?

A

Somatostatin

19
Q

Outside of a pituitary adenoma, what is another cause of acromegaly?

A

Ectopic release of GH: May be seen in neuroendocrine tumours.

Ectopic release of GHRH: Related to tumours including carcinoid and small cell lung cancer.

Excess hypothalamic release of GHRH: Related to hypothalamic tumours.

20
Q

What is pituitary gigantism?

A

Growth hormone secreting somatotroph adenomas develop in childhood prior to fusion of the epiphyseal growth plates

21
Q

What are the clinical features of acromegaly?

A

Symptoms -

Headaches, arthralgia, sweating, increased ring/shoe size, weakness,
diabetes, carpal tunnel, atherosclerosis

Signs

  • Enlargement of hands, feet, lips and nose
  • Wide spaced teeth,
  • Prognathism (protrusion of lower jaw)
  • Frontal bossing
  • Men may note a deepening of their voice and some patients develop carpal tunnel syndrome.

prominent supraorb ridge, bi-temporal
hemianopia, hypertension

22
Q

Which conditions does GH and IGF-1 excess predispose patients to?

A

Cardiovascular disease: hypertension, cardiomyopathy, left ventricular hypertrophy and heart failure.

Insulin resistance: causing risk of type 2 diabetes

Obstructive sleep apnea

Organomegaly : enlargement of visceral organs e.g liver, kidneys, heart, prostate and lungs.

Colonic pathology: increased risk of colorectal cancer and diverticulosis.

Thyroid gland: Enlargement of the thyroid gland either a diffuse enlargement or multinodular. may be an increased incidence of thyroid cancer.

Headache: may be related to mass effect from a pituitary adenoma or as a result of GH excess itself.

23
Q

Which other protein can be secreted in excess in those with acromegaly? What are the consequences of this?

A

Prolactin causing hyperprolactinaemia

Features

  • galactorrhea,
  • dysmenorrhoea,
  • hypogonadism and infertility
24
Q

What is the difference between the the release of GH and IGF-1 throughout the day?

A
  • IGF-1 Levels - constant levels

GH - shows a great deal of variation depending on the time of day and various stressors

25
Q

Which biochemical tests are used to assist with diagnosing acromegaly

A

IGF levels - raised serum IGF-1 that reflects periods of excess GH

High = confirms diagnosis
Equivalent = Carry out oral glucose tolerance test
Low
Normal = Acromegaly unlikely

Oral glucose tolerance test-
Very specific diagnostic test
- give 100g of oral glucose
- Measure Serum GH before and after glucose

Normal = GH release is suppressed
Abnormal = GH levels are unsuppressed.
26
Q

Which imaging tests are used to assist with diagnosing acromegaly

A

Pituitary MRI -

  • confirms the diagnosis and guide surgical management.
  • Small adenomas cannot always be seen
27
Q

How are extra-pituitary causes of acromegaly investigated?

A

GHRH levels: Elevated levels indicate excess production from a hypothalamus tumour or ectopic source.

CT chest, abdomen and pelvis: Used to look for evidence of tumours that may lead to acromegaly through GH or GHRH production (e.g. small cell lung cancer, carcinoid).

Octreoscan & DOTATATE PET: Further scans that can be used to locate tumours that may produce GH/GHRH.

28
Q

How is acromegaly treated?

A

Surgery

  • Transphenoidal surgery - first line
  • Microadenomas tend to have better results than macroadenomas.

Medical
Used in those who are not operative candidates or when surgery does not produce biochemical cure

Somatostatin analogs (Octreotide) - monthly injection to reduce release of GH and may cause shrinkage of tumours

Growth hormone antagonists (Pegvisomant)
- daily injection, lowers IGF-1 levels

Dopamine agonists (e.g. Bromocriptine) -

  • reduce the release of GH
  • Only effective for some
  • Tablet form

Radiotherapy
- reserved for cases where surgery and medical management fails

Risks include the development hypopituitarism; therefore, it is generally avoided in those of reproductive age.

29
Q

Describe the cancer screening process for acromegaly

A

Acromegaly = increased risk of colorectal and thyroid cancer

Colorectal cancer

  • colonoscopy and regular screening from the age of 40
  • frequency dependant on findings in initial examination and acromegaly disease activity

Thyroid cancer
- Routine screening for thyroid cancer is not generally advised

30
Q

What is hypopituitarism ?

A

ACTH, GH, FSH, LH, TSH, PRL

31
Q

List 3 causes of hypopituitarism

A

Adenoma, Irradiation,
Infarction (Sheehans),
Infiltration
(Sarcoid, TB)

32
Q

What are the signs and symptoms of hypopituitarism?

A

Symptoms
Loss of libido, weakness,
amenorrhoea, impotence,
depression, hypothyroidism

Signs 
Pallor, Hypothyroid, Absent
pubic/axillary hair, Testicular
atrophy, Visual field defect,
Postural hypotension
33
Q

How is hypopituitarism investigated?

A

Insulin Stress Test
Low T4, Test, Oestradiol with
low FSH, LH, TSH, ACTH
MRI pituitary

34
Q

How is hypopituitarism treated?

A

Hormone replacement –
Hydrocortisone first, T4,
testostorone, HRT,
Ovulation induction

35
Q

What is pituitary apoplexy?

A

Abrupt acute hemorrhagic infarction of a pituitary adenoma

36
Q

what are the symptoms of pituitary apoplexy?

A 
acute headache,
▪
 meningism,
▪
 visual impairment,
▪
 ophthalmoplegia,
▪
 Low GCS
37
Q

How is pituitary apoplexy treated?

A 
Glucocorticoid replacement is the
most important first step due to
adrenal insufficiency
▪ Followed by urgent surgical
decompression

MET3B (17 decks)

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