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Unit 10 lectures > Endocrinology conditions > Flashcards

Endocrinology conditions Flashcards

1
Q

Embryology

A

Hypothalamus:
- develops from neuroectoderm of the forebrain
- GNRH, TRH, CRH, GnRH, dopamine, somatostatin

Neurohypophysis:
- evagination of ventral hypothalamus and 3rd ventricle
- vasopressin, oxytocin

Adenohypophysis:
- derived from Rathke’s pouch - ectoderm - oropharynx
- ACTH, LH, FSH, TSH, GH, PRL

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2
Q

Hypothalamic-pituitary axis

anterior pituitary hormones

A

Stimulatory hypothalamic hormones → anterior pituitary hormones |— inhibitor hypothalamic hormones

Examples:

GnRH → FSH, LH

GHRH → GH
|— somatostatin

TRH → TSH and prolactin
|— somatostatin for TSH and dopamine for both

VIP, PHI → prolactin |— dopamine

CRH → ACTH

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3
Q

Posterior pituitary

A

Arginine vasopressin - controls fluid balance
Oxytocin

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4
Q

Clinical presentations of pituitary tumours

A

Hormone hyper-secretin

Space occupying lesion:
→ headaches
→ visual loss (field defects)

Hormone deficiency states:
→ interference with surrounding normal pituitary

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5
Q

Tumours of the anterior pituitary can cause syndromes of hormone excess

A

ACTH → Cushing’s disease (pituitary problem causing excess cortisol)

TSH → secondary thyrotoxicosis

GH → acromegaly

LH/FSH → (non-functioning pituitary tumour)

PRL → prolactinoma

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6
Q

Pressure on optic chiasm

A

Pressure on the optic chiasm caused by a tumour can lead to:

→ field of vision loss - bitemporal hemianopia

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7
Q

Non-functioning pituitary tumours

A

→ majority of all pituitary tumours

→ no syndrome of hormone excess produced

→ cause symptoms due to space occupation
- headache
- visual field defects - as pressure on optic chiasm
- pituitary function - deficiency of hormones

→ treatment
- endoscopic trans-sphenoidal hypophysectomy - surgery done through the nose

→ radiotherapy
→ no effective medical therapy

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8
Q

Acromegaly

A

→ enlarged extremities
→ usual onset at age 40-60 (gigantism if pre-puberty)
→ occasionally familial in association with MEN I
→ mortality is twice that of the general population

Presents as :
- signs of GH symptoms
- pressure symptoms
- field defects
- loss of anterior pituitary function

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9
Q

Acromegaly symptoms

A
  • course facial features
  • soft tissue thickening
  • excessive sweating
  • hypertrichosis
  • carpel tunnel syndrome
  • headaches
  • thick lips, enlarged nose
  • spade like hands
  • frontal bossing
  • macroglossia
  • prognathism and separation of teeth
  • snoring and obstructive sleep apnoea syndrome
  • enlargement of supraorbital ridges
  • kyphosis
  • goitre
  • myopathy
  • hypertension, diabetes mellitus, heart failure
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10
Q

Tests for acromegaly

A

Diagnosis:

→ raised insulin like growth factor 1 (IGF1) - integrated effect of growth hormone (GH) at tissue level

→ oral glucose tolerance test (GTT) with GH measurement - GH should suppress completely

→ imaging - MRI pituitary with Gadolineum contrast

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11
Q

Acromegaly treatment

A

→ endoscopic transnasal transsphenoidal surgery

→ somatostatin analogues - Octreotide, Lanreotide, Pasireotide
(somatostatin inhibits GH secretion)

→ radiotherapy

→ growth hormone receptor antagonist - pegvisomant

→ dopamine agonist therapy - bromocriptine, cabergoline - less effective
(Dopamine inhibits GH secretion)

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12
Q

Prolactin physiology

A

→ prolactin secretion is toxically inhibited by one or more prolactin inhibiting factors (PIFs)

→ dopamine is the most important of these

> originates from hypothalamic tubero-infundibular tract and reaches lactotroph via hypophyseal portal vessels

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13
Q

Clinical manifestations of hyperprolactinaemia

A

Women:
- galactorrhoea 30-80%
- menstrual irregularity
- infertility
Men:
- visual field abnormalities
- headache
- galactorrhoea (uncommon)
- impotence
- anterior pituitary malfunction

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14
Q

Prolactinoma

A

→ prolactinoma is the second most common pituitary tumour after chromophobe adenoma

→ anything that interrupts the dopamine inhibitory pathway can result in hyperprolactinaemia

→ hyperprolactinaemia is often drug induced - particularly by antipsychotic medication

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15
Q

Hyperprolactinaemia Treatment

A

→ dopamine inhibits prolactin secretion
→ prolactin suppression can shrink tumour

→ dopamine agonists - bromocriptine, cabergoline, quinagolide

→ surgery
→ radiotherapy

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16
Q

Causes of hypopituitarism

A
  • pituitary tumours
  • pituitary surgery
  • pituitary radiotherapy
  • pituitary infarction - Sheehan’s syndrome
  • pituitary apoplexy
17
Q

Cushing’s disease

A

→ too much cortisol
→ often caused by taking too many steroids or by anterior pituitary tumour

Symptoms:
- increased fat on chest and tummy but slim arms and legs
- a build-up of fat on the back of the neck ‘buffalo hump’
- red, puffy, round face
- bruises easily
- large purple stretch marks
- weakness in upper arms and thighs
- depression and mood swings
- low sex drive

18
Q

Cushing’s syndrome clinical features

A

Due to pituitary adenoma = Cushing’s disease

Clinical features:
- ‘moon faces’
- interscapular fat
- central obesity weight gain
- proximal myopathy
- hypertension
- malaise
- psychoses
- hirsuitism and acne
- skin thinning
- oligo-or amenorrhoea
- bruising
- polyuria, nocturia
- decreased libido
- purple ‘angry’ striae
- backache / kyphosis
- renal caniculi

19
Q

Cushing’s syndrome test and diagnosis

A

Screening:
→ 24 hour urinary free cortisol
→ overnight Dexamethasone suppression test

Confirming:
→ low dose Dexamethasone suppression

Source:
→ ACTH measurement
→ high dose dexamethasome - 50% fall in 80-90% with pituitary disease
→ CRF test - normal or exaggerated response of ACTH in Cushing’s disease

20
Q

Cushing’s syndrome - tumour localisation

A

Tumour localisation:

Pituitary
→ MRI
→ petrosal sinus sampling +/- CRH

Adrenal
→ MRI
→ selective venous catheterisation

Ectopic
→ MRI/CT

21
Q

Chushing’s syndrome - treatment

A

Surgical:
→ transphenoidal, adrenal

Medical:
→ adrenolytic therapies may be used in preparation for surgery (metyrapone, mitotane, ketaconazole, etomidate)
→ Chemotherapy - oat cell, carcinoid
→ Radiotherapy

22
Q

Addison’s disease symptoms - Primary adrenocortical failure

A

Symptoms:
- weakness and fatigue
- anorexia and weight loss
- abdominal pain
- postural hypotension
- pigmentation due to ACTH hypersecretion (this makes skin look tanned)

23
Q

Addison’s disease - aetiology and presentation

A

Addison’s disease - primary hypo-adrenalism

Aetiology:
- most cases are now autoimmune
- females twice as likely to have it
- previously TB more common
- occasionally direct tumour invasion or metastasis, AIDS

Presentation:
- lethargy, weakness, postural hypotension, weight loss, abdominal pain, nausea and vomiting
- pigmentation - at sites of trauma, buccal mucosa, axillae, groins, genitalia, skin creases, scars

24
Q

Addison’s disease - biochemistry, investigation and treatment

A

Biochemistry:
- serum sodium normal or reduced
- serum potassium increased
- urea increased (dehydration)
- may be hypoglycaemic

Investigation:
- basal cortisol
- adrenal antibodies
- short synacthen test

Treatment:
- emergency - IV fluids, IV hydrocortisone 100mg stat, then IV hydrocortisone 50mg 6 hrly or as infusion
- replacement - hydrocortisone per oral 20mg/day in divided doses, fludrocortisone 50 to 200mg/day

25
Q

Hyperthyroidism

A
  • syndrome resulting from excess of free T4 and/or free T3
  • more common in women
  • hyperthyroidism indicates thyroid gland overactivity
  • T3 toxicosis (raised FT3 but normal FT4) is earliest phase and is found in some cases
26
Q

Causes of hyperthyroidism

A

Primary hyperthyroidism:
→ Graves’ disease (large majority of all cases of hyperthyroidism)
→ toxic multinodular goitre
→ toxic adenoma

Thyrotoxicosis without hyperthyroidism:
→ excessive T4 administration
→ thyroiditis - post-partum, de Quervain’s, amiodarone induced thyrotoxicosis
→ new immune therapy drugs

27
Q

Clinical features of hyperthyroidism

A

Symptoms:
- weight loss
- increased appetite
- heat intolerance and sweating
- fatigue and weakness
- hyperactivity, irritability, insomnia, palpations
- tremor
- diarrhoea

Physical signs:
- lid lag, lid retraction
- tremor
- hyperreflexia
- tachycardia, AF (in over 50s)
- warm moist skin, hair loss, onycholysis

28
Q

Hyperthyroidism - treatment

A

→ antithyroid drugs - carbimazole, propyl thiouracil

→ radioactive iodine therapy

→ thyroidectomy

29
Q

Common causes of primary thyroid failure

A
  • autoimmune thyroiditis
  • idiopathic atrophy
  • previous Rx with radioiodine or thyroidectomy
  • iodine deficiency
  • antithyroid drugs
  • subacute and silent thyroiditis
30
Q

Clinical features of primary thyroid failure

A
  • onset may be insidious
    > non-specific and vague symptoms
  • presenting symptoms and signs diverse
  • reflect widespread action of thyroid hormones
  • reflect widespread action of thyroid hormones
  • in mild disease symptoms and signs are often absent
  • tiredness and lethargy
  • weight gain
  • control intolerance
  • hyperlipidaemia
  • Bradycardia
  • delayed relaxation of reflexes
  • aches and pains
31
Q

Hypothalamic-pituitary gonadal (HPG) axis

A

Hypothalamus → GnRH → pituitary → LH and FSH → testis → testosterone → back to hypothalamus or pituitary

Or

Hypothalamus → GnRH → pituitary → LH and FSH → ovary → oestrogen and progesterone → back to hypothalamus or pituitary

32
Q

HPG dysfunction

A

Problems with sexual maturation/secondary characteristics:
- precocious puberty
- short stature
- delayed puberty

Men
- hypogonadism
- infertility
- erectile dysfunction

Women
- infertility
- secondary amenorrhoea
Pituitary causes
Gonadal causes

33
Q

Summary of endocrinological diseases

A

Pituitary hyper-secretion:
- acromegaly
- Cushing’s disease
- prolactinoma

Pan-hypopituitarism
- HPA axis
(adrenal hyper-secretion - Cushing’s)
(adrenal hypo-function - Addison’s)
- HPT axis
- HPG axis

Unit 10 lectures (14 decks)

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