Endocrinology Flashcards

1
Q

Where is the pituitary gland located

A

sella turcica of the sphenoid bone, attached to the hypothalamus

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2
Q

What hormones are secreted from the anterior pituitary

A
o Growth Hormone
o Prolactin
o FSH
o LH
o TSH
o ACTH
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3
Q

What is the difference of the hypothalamic involvement between hormones secreted from the anterior and posterior pituitary

A

ANT: these hormones are regulated by hormones from the hypothalamus

POS: these are synthesised in the hypothalamus - pass into the posterior pituitary to be secreted

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4
Q

What hormones are secreted from the posterior pituitary

A

o Oxytocin

o ADH

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5
Q

What is the most common disease of the anterior pituitary

A

Pituitary adenoma

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6
Q

What type of tissue is most commonly affected with a pituitary adenoma

A

Glandular tissue

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7
Q

What are the most common causes of pituitary adenoma

A

Most cases are sporadic, but they can occur as part of the MEN1 syndrome

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8
Q

What are the 2 main types of pituitary adenoma and how do they present

A

o Functional adenomas = Effects related to excess hormone secretion (very small at presentation - because the symptoms mean they are picked up earlier)
o Non-functional adenomas = don’t produce hormones - larger and therefore present with mass effects (however many are not detected - as they remain small)

” Mass effects
o Bitemporal hemianopia - due to compression of the optic chiasm, thereby affecting the optic nerves
o Diplopia - compression of CN III, IV, VI
o Non-specific symptoms of a intracranial mass ie headache

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9
Q

What is a prolactinoma

A

Pituitary adenomas that produce excess prolactin

They are the most common type of functional adenoma

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10
Q

How would a prolactinoma present in a woman of reproductive age

A

Oligomenorrhoea - infrequent/light menstruation (4-9 periods a year)
OR
Galactorrhoea - spontaneous flow of milk from the breast unassociated with pregnancy or breast feeding

(Note these patients generally have small tumours and present early)

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11
Q

How would a prolactinoma present in a man/post-menopausal woman

A

” Mass effects - headache / visual disturbance
OR
“ Galactorrhoea (occasionally)
These patients generally have larger tumours on presentation.

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12
Q

How do ACTH secreting adenomas present

A

Cushing’s syndrome

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13
Q

How do GH secreting tumours present

A

Acromegaly

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14
Q

List symptoms of acromegaly

A
" Facial changes
o Protruding supraorbirtal ridges
o Enlarged nose
o Coarse facial features
o Prognathia
" Headaches
" Thickened calvaria
" LV hypertrophy
" HTN
" Insulin resistance
" Hepatomegaly
" Impotence and loss of libido / amenorrhoea in women
" Large hands
" Thickened skin
" Hyperostosis
" Degenerative joint disease
" Peripheral neuropathy (nerve compression)
" Large feet and heel pad
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15
Q

Mortality is doubled in patients with acromegaly- why

A

Mainly due to high incidence of CVD due to LV hypertrophy and HTN.
Also has another risk factor for CVD as it is a diabetogenic state (insulin resistance)

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16
Q

How do TSH secreting adenomas present

A

Thyrotoxicosis

not a very common cause of thyrotoxicosis though!

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17
Q

What are common causes of thyrotoxicosis

A
" Graves (80%)
" Toxic multinodular goitre - secretes thyroid hormone independently of TSH
" A functional thyroid adenoma
" Drugs - amiodarone
" Thyroiditis (certain types)
18
Q

Where are the adrenal glands located

A

located in the retroperitoneum, superior to the kidneys

19
Q

What are the functional divisions of the adrenal glands

A

Cortex and medulla

20
Q

How is the adrenal cortex divided

A

o Zona glomerulosa = mineralocorticoids (ALDOSTERONE)
o Zona fasiculata = glucocorticoids (CORTISOL)
o Zona reticularis = ANDROGENS

21
Q

What does the medulla of the adrenal gland secrete

A

catecholamines - eg. adrenaline + noradrenaline

22
Q

How does the HPA axis regulate cortisol

A
  1. Hypothalamus secretes CORTICOTROPHIN RELEASING HORMONE - CRH
  2. Stimulates the anterior pituitary to secrete ACTH
  3. ACTH acts on the adrenal gland to stimulate the release of cortisol
  4. Cortisol has a negative feedback effect on both the hypothalamus and anterior pituitary - supressing CRH and ACTH
23
Q

What is Cushing’s syndrome

A

A metabolic disorder due to persistent excess circulating glucocorticoids

24
Q

List symptoms of Cushing’s syndrome

A
  • Weight gain - pattern of fat deposition = marked trunkal obesity and a moon face
  • Muscle weakness - proximal myopathy.
  • Gonadal dysfunction = menstrual irregularities in women and loss of libido in men
  • Hirsuitism in women
  • HTN - secondary
25
What is the most common cause of Cushing's syndrome
Exogenous administration of glucocorticoids
26
List the main causes of Cushing's syndrome
1. Exogenous administration of glucocorticoids 2. Pituitary adenoma which secretes ACTH 3. An adrenal cortical adenoma which secretes cortisol 4. Paraneoplastic syndrome
27
A patient with cushing's syndrome has adrenals that have atrophied. What is the most likely cause behind their symptoms?
Exogenous administration of glucocorticoids
28
A patient with cushing's syndrome has adrenals that have undergone hyperplasia. What is the most likely cause behind their symptoms?
Pituitary adenoma secreting ACTH
29
What is Cushing's disease
Pituitary adenoma which secretes ACTH
30
A patient with Cushing's syndrome is found to have an adrenal cortical adenoma. Which cells will this have arisen from? (not specific, just wants the location)
Cells in the zona fasciculata
31
What is the equation for BP
BP= CO x TPR
32
What are the 2 main factors affecting BP
Vasoconstriction - TPR | Increase in Na+ retention (+ H2O = + circulating volume = + CO)
33
What is the equation for CO
CO= HR x SV
34
What is the most common cause of primary hyperaldosteronism?
Conn's syndrome (aldosterone producing adrenal cortical adenoma)
35
What is the second most common cause of primary hyperaldosteronism
Bilateral adrenal cortical hyperplasia
36
Briefly explain RAAS
1. If BP falls there is reduced blood flow to the renal artery 2. This hypoperfusion stimulates release of renin 3. Results in the production of Ang II. Its effects include: a. Stimulates release of aldosterone from the adrenal cortex. Aldosterone increases Na+ (and water) reabsorption by the kidney tubules - increases blood volume and raises BP b. Vasoconstriction of arterioles (systemic) = raises BP c. Stimulates release of ADH by posterior pituitary - stimulates water reabsorption - increases blood volume = raises BP 4. Restoration of blood flow = less renin released and so downregulates renin
37
What are the effects of Ang II
a. Stimulates release of aldosterone from the adrenal cortex. Aldosterone increases Na+ (and water) reabsorption by the kidney tubules - increases blood volume and raises BP b. Vasoconstriction of arterioles (systemic) = raises BP c. Stimulates release of ADH by posterior pituitary - stimulates water reabsorption - increases blood volume = raises BP
38
What are the main effects of hyperaldosteronism
- Excess Na+ reabsorption = hypernatreamia - Excess K+ loss into urine = hypokalaemia - Excess Na+ retention = excess H2O reabsorption = + circulatory volume = + CO = + BP
39
What is a phaeochromocytoma
Neuroendocrine tumour of the adrenal medulla, which secretes catecholamines
40
What is the main effect of a phaeochromocytoma
Hypertension
41
How do phaeochromocytomas present
Usually asymptomatic - may complain of episodes of throbbing headache/sweating/palpitation (due to episodic increases in circulating catecholamines).
42
How do you investigate a suspected phaeochromocytoma
24h urine collection for catecholamine and metanephrine measurement