Endocrinology Flashcards

1
Q

Outline the mechanism of primary hypothyroidism.

A

Low T4

High TSH and TRH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the causes of primary hypothyroidism?

A

Autoimmune: Hashimoto’s thyroiditis

Atrophic thyroiditis

Thyroidectomy

Radioactive iodine

Drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the management of primary hypothyroidism?

A

Replace thyroxine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Outline the mechanism of secondary hypothyroidism.

A

Pituitary gland failure

Low T4

TSH and TRH are low

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Outline the mechanism of thyrotoxicosis.

A

Negative feedback loop

High T4

TSH and TRH are low

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are some of the causes of thyrotoxicosis?

A

Autoimmune: Graves’ disease

Multinodular goitre

Single toxic nodule

Thyroiditis: viral, post-partum, drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the management of thyrotoxicosis?

A

Beta-blocker for symptoms

Antithyroid medication: carbimazole

Radioactive iodine

Surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Outline the mechanism of a TSH-secreting pituitary tumour.

A

High T4

High TSH

Low TRH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the general theory behind dynamic testing?

A

If you think there is not enough hormone –> try to stimulate
e.g. short synacthen test, insulin tolerance test

If you think there is too much hormone –> try to suppress
e.g. glucose tolerance test, dexamethasone suppression test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the signs and symptoms of acromegaly?

A

Excess growth hormone production

  • large, “spade-shaped” hands and feet
  • coarse features: prominent supraorbital ridge, large nose, separated teeth, protruding jaw
  • headache
  • visual field defects: bitemporal hemianopia
  • excessive sweating
  • carpal tunnel syndrome
  • cardiomegaly and hypertension
  • glucosuria and polyuria
  • abnormal glucose tolerance test
  • arthrosis
  • sexual dysfunction
  • peripheral neuropathy
  • galactorrhoea
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Outline the hormones produced by the pituitary gland.

A

HYPOTHALAMUS PITUITARY GLAND END-ORGAN
GnRH LH & FSH Ovaries/testes (androgens –> sperm, oestrogens –> ovulation)
GHRH GH Liver (growth factor)
Dopamine (-)Prolactin Breasts/gonads (lactation)
TRH TSH Thyroid (thyroxine)
CRH ACTH Adrenals (steroid hormones)
ADH Renal tubules
Oxytocin Breasts/uterus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the investigations in acromegaly?

A
  • TSH & T4
  • prolactin
  • FSH & LH
  • GH
  • insulin growth factor-1
  • glucose tolerance test
  • MRI pituitary fossa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the management of acromegaly?

A

Surgery: transphenoidal

Radiotherapy: conventional or gamma-knife

Medical: somatostatin analogue (octreotide), GRH blockers (pegvisomant)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is growth hormone?

A

Peptide hormone causing musculoskeletal and vertebral growth and gluconeogenesis

Inhibited by somatostatin

Pulsatile

Glucose tolerance test: increases somatostatin –> should suppress GH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does an excess or deficiency of growth hormone cause?

A

EXCESS

  • children = gigantism (epiphyses fail to fuse)
  • adults = acromegaly

DEFICIENCY

  • children = proportional dwarfism
  • adults = weight gain, muscle loss (insulin tolerance test - contraindicated in IHD and epilepsy)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the signs and symptoms of Cushing’s syndrome?

A
  • plethoric, moon facies, dorsal hump
  • bruising, thin skin, purpura, poor wound healing, abdominal striae
  • central obesity
  • cardiac hypertrophy and hypertension
  • adrenal tumour/hyperplasia
  • myopathy
  • amenorrhoea
  • diabetes
17
Q

What is Nelson’s syndrome?

A

Development of ACTH-secreting tumour following bilateral adrenalectomy for Cushing’s disease

18
Q

What are the investigations in Cushing’s disease?

A
  • 24hr urinary cortisol x 3
  • ACTH
  • midnight cortisol
  • low dose dexamethasone suppression test = 0.5mg qds 48hrs (excludes pseudo-Cushing’s)
19
Q

What are the differentials for Cushing’s disease?

A
  • ACTH secreting pituitary
  • ectopic ACTH-secreting tumour
  • adrenal tumour

Differentiate using high dose dexamethasone suppression test, CRH test, petrosal sinus sampling, MRI pituitary fossa

20
Q

Contrast pituitary and adrenal Cushing’s.

A

Pituitary:

  • high cortisol
  • high ACTH

Adrenal:

  • high cortisol
  • low ACTH
21
Q

Outline the mechanism of Addison’s disease.

A

Low steroid hormones

High ACTH

22
Q

What are the signs and symptoms of Addison’s disease?

A
  • hyponatraemia
  • hyperkalaemia
  • postural hypotension
  • bronze pigmentation
  • GI disturbance
  • weight loss
  • weakness
  • hypoglycaemia
  • change in distribution of body hair
23
Q

What are the causes of primary adrenal insufficiency?

A

Autoimmune

TB

Iatrogenic

Sepsis

Infiltrative disease

Friedrich-Waterhouse syndrome (haemorrhagic adrenalitis, fulminant meningoccocaemia)

Adrenal leucodystrophy

24
Q

What is the management of a hypoadrenal crisis?

A
  • fluids
  • glucose
  • steroids: hydrocortisone 100mg IV 6hrly
  • treat sepsis
  • find cause
25
Q

What are the investigations in Addison’s disease?

A
  • 9:00AM cortisol
  • ACTH level
  • renin
  • short synacthen test: giving ACTH fails to increase cortisol levels
26
Q

What is the long-term management of Addison’s disease?

A
  • hydrocortisone (10/5/5mg)
  • fludrocortisone (50-100mg)
  • education
  • emergency hydrocortisone injection kit
  • endrocrinology follow-up
27
Q

Outline the mechanism of hyperprolactinaemia.

A

Prolactin is under tonic inhibitory control by dopamine

Prolactin elevated by dopamine antagonists e.g. haloperidol, olanzapine, domperidone, metoclopramide

Prolactin decreased by dopamine agonists e.g, bromocriptine, pregabalin

28
Q

What are the signs and symptoms of hyperprolactinaemia?

A
  • galactorrhoea
  • secondary amenorrhoea/oligomenorrhoea
  • dysmenorrhoea
  • infertility
29
Q

What are the causes of hyperprolactinaemia?

A

Macroadenoma of pituitary gland –> low blood supply to desc. dopaminergic inhibition –> reduced inhibition of prolactin

Non-functioning prolactinoma

5Ps = pregnancy, physiological, pharmacology, PCOS, primary hypothyroidism