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Year 2 - Endocrine > Week 4 > Flashcards

Week 4 Flashcards

1
Q

In what context is a low sodium serious?

A

If it is under 120 mmol/L

If it has rapidly fallen from normal to almost serious levels - this too can be severe

NB - this also applies to hypernatraemia

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2
Q

Sodium is confined to the (intracellular/extracellular) fluid

A

extracellular

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3
Q

What other ion mirrors sodium? What pump is used by these two to interact?

A

Potassium

The Na+/K+-ATPase pump

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4
Q

Too much mineralocortiocoid (i.e. aldosterone) activity means (loss/retention) of sodium

Too little mineralocortiocoid (i.e. aldosterone) activity means (loss/retention) of sodium

A

Too much aldosterone = sodium retention

Too little aldosterone = sodium loss

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5
Q

Increased ADH = (lowered/raised) urine concentration

Decreased ADH = (lowered/raised) urine concentration

A

Increased ADH = raised concentration of urine

Decreased ADH = dilute urine

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6
Q

Patient presents with DKA and has been vomiting a lot, therefore has lost a lot of fluid

How does this affect Sodium?

A

Raised plasma sodium (water loss exceeds sodium loss) i.e. hypernatraemia

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7
Q

How does Addison’s disease result in hyponatraemia and hyperkalaemia?

A

Damage to adrenal gland = cannot make mineralocorticoids (mainly aldosterone)

Lack of aldosterone = inability to retain sodium, lost in the urine.

Low sodium also means Na+/K+-ATPase pump cannot function, so potassium is retained.

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8
Q

Where are the anterior and posterior pituitary derived from, embryologically?

A

Anterior - derived from Rathke’s pouch

Posterior - extension of neural tissue consisting of modified glial cells and axonal processes

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9
Q

What type of cells secrete the following hormones in the anterior pituitary

  • GH
  • PRL
  • LH/FSH
  • TSH
  • ACTH
A

GH - somatotrophs

PRL - mammotrophs

LH/FSH - gonadotrophs

TSH - thyrotrophs

ACTH - corticotrophs

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10
Q

What genetic defect are Pituitary Adenomas associated with?

A

MEN1

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11
Q

Name some posterior pituitary syndromes

A

SIADH

Diabetes insipidus

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12
Q

How much do the adrenal glands weigh?

A

4-5g each

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13
Q

What is Waterhouse-Friderichsen Syndrome?

A

Acute adrenocortical hypofunction

Caused by bleeding into the adrenal glands, commonly due to severe bacterial infection (typically Neisseria meningitides)

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14
Q

What cell type are phaeochromocytomas derived from?

What do they secrete?

A

Derived from Chromaffin cells in the adrenal medulla

Secrete catecholamines (adrenaline, noradrenaline

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15
Q

Phaeochromocytoma - presentation

A

Hypertension (90%) - paroxysmal episodes are common, brought about by stress, exercise, postural changes, palpation of tumour

Complications - cardiac failure, infarctions, arrhythmias

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16
Q

Phaeochromocytoma - investigation

A

Detection of urinary excretion of catecholamines and metabolites

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17
Q

Why are phaeochromocytomas known as the “10% tumour”?

A

10% are extra-renal

10% are bilateral

10% are biologically malignant

10% are NOT associated with hypertension

(25% are familial)

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18
Q

What special feature do phaeochromocytomas exhibit histologically?

A

Tumour cells cluster together and form nests - zellballen

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19
Q

What genetic defect are phaeochromocytomas associated with?

A

MEN2A

MEN2B

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20
Q

What does each layer of the adrenal cortex secrete?

A

Zona Glomerulosa - secretes mineralocorticoids (e.g. aldosterone)

Zona Fasciculata - secretes glucocorticoids (e.g. cortisol)

Zona Reticularis - sex steroids and glucocorticoids

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21
Q

Why should a fluid bolus not be given to a child with DKA (unless you suspect they are in shock)?

How is this risk moderated?

A

Because of the risk of cerebral oedema

In order to minimise the risk of cerebral oedema, start giving IV fluids 1 hour before giving insulin

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22
Q

If a child presents to you in clinic and you suspect DKA, at what point would you arrange immediate hospitalisation?

A

Child presents with elevated blood glucose, no ketones in urine and clinically well - urgent referral to paediatric team and arrange review in 24 hours

Child presents with elevated blood glucose, ketones present in urine and clinically well - urgent referral to paediatric team and same day review

Child presents with elevated blood glucose, ketones in urine and symptoms of DKA - immediate emergency referral via ambulance

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23
Q

What is the first clinical sign that will be seen in diabetic nephropathy?

What other microvascular complications might develop?

A

Microalbuminuria is the first sign to appear

Sensory nerve damage

Diabetic retinopathy

Skin vascular changes

Diabetic cheiroarthrpathy (thickened skin and swelling of the joints)

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24
Q

16 year old patient with type 1 DM needs to work out how much insulin to take prior to a meal.

Current bloog glucose = 10 mmol

Having lasagne = 70g carbohydrate

Carb ratio is 1:10 i.e. 1 unit of insulin = 10g carbs

Insulin sensitivity is 1:2 i.e. 1 unit of insulin = drop of 2 mmol glucose

Target blood glucose is 6 mmol

A

Currently at 10, target is 6, therefore 2 units to bring to desired blood glucose

70g carbohydrates will require 7 units to cover

7 + 2 = 9 units of insulin total

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25
Q

Congenital thyroid disease in the young - presentation

A

Jaundice is the most common symptom

Poor feeding but “normal” weight gain

Hypotonia (“floppy baby syndrome”)

Skin and hair changes

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26
Q

How is congenital thyroid disease screened for?

When is this done? Why?

A

By performing the Guthrie Test - pin prick blood test taken from the heel of the baby that screens for a variety of diseases, including measuring TSH levels

Performed at day 5, as babies have a naturally high TSH when first born

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27
Q

What does continued absence of thyroxine in a baby result in?

A

Absence of thyroxine after 3 months of life leads to global developmental delay - cretinism

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28
Q

What is the most common cause of acquired thyroid disease in the young?

What are some of the other causes?

A

Most common cause - autoimmune

Other causes - post-infectious, delayed congenital, iodine deficiency

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29
Q

How do hypo and hyperthyroidism present in the young?

A

Hypothyroidism

  • slow progress
  • failure to grow, delayed puberty
  • poor general health
  • educational difficulties

Hyperthyroidism

  • general symptoms - behaviour problems, anxiety, restlessness, sleep disturbances
  • Goitre - more likely than in hypo
  • precocious puberty
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30
Q

How would virilisation as a result of Congenital Adrenal Hyperplasia (and therefore excess testosterone) present in a) boys and b) girls

A

Boys - precocious puberty

Girls - ambiguous genitalia

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31
Q

Congenital Adrenal Hyperplasia can cause a deficiency in Aldosterone and Cortisol, which could precipitate an Addisonian Crisis.

What are the 3 main features of an Addisonian Crisis?

A

Hyponatraemia

Hyperkalaemia

Hypotension

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32
Q

During development, what are the names of the male and female ducts?

What causes the regression of each?

How is this affected by CAH?

A

Male duct - Wollfian ducts, regression is caused by a lack of testosterone (due to the presence of ovaries)

Female duct - Mullerian ducts - regression is caused by anti-Mullerian Hormone produced by Sertoli cells

In CAH, there is excess testosterone produced and so the Wollfian ducts will not regress, hence the appearance of ambiguous genitalia

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33
Q

How are a) monogenic disorders and b) polygenic disorders best evaluated?

A

Monogenic - historically done through study of families (linkage studies). Now done with Next Gen Sequencing

Polygenic - evaluated by looking at large populations (GWAS - genome-wide association studies)

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34
Q

MEN1 and MEN2 defects are classic examples of (monogenic/polygenic) disorders

Can you name some more?

A

Monogenic

McCune-Albright

Carney Complex

Von-Hippel Lindau disease

Neurofibromatosis type I

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35
Q

Defects in which genes cause the following conditions?

  • MEN1
  • MEN2
  • McCune-Albright
  • Carney complex
  • Von-Hippel Lindau
  • Neurofibromatosis type I
A

MEN1 - MEN1 gene

MEN2 - RET gene

McCune-Albright - GNAS1 gene

Carney Complex - PRKAR1A gene

Von-Hippel Lindau - VHL gene

Neurofibromatosis I - NF1

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36
Q

How do MEN1 and MEN2 disorders differ in terms of requirements for pathology to occur?

A

MEN1 - “two hits”, requires inactivation and tissue activation. MEN1 is a classic tumour suppressor gene

MEN2 - “one hit”, just needs activation as MEN2 is a proto-oncogene

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37
Q

What conditions are the different MEN disorders assocaited with?

A

MEN1 (3 P’s) - pituitary adenoma, parathyroid hyperplasia, pancreatic cancer

MEN2A - parathyroid hyperplasia, medullary thyroid carcinoma, phaeochromocytoma

MEN2B - mucosal neuromas, Marfanoid body habitus, medullary thyroid carcinomas, phaeochromocytomas

38
Q

How might someone with McCune-Albright syndrome present clinically?

A

Cafe-au-lait macules (Coast of Maine appearance)

Polyostotic fibrous displasia (affecting bones)

Precocious puberty (mainly females)

Thyroid nodules

GH excess

Cushing’s syndrome

39
Q

The mutation seen in Von-Hippel Lindau is (autosomal dominant/autosomal recessive)

A

Autosomal dominant

40
Q

What regulates each layer of the adrenal cortex?

A

Zona Glomerulosa - regulated by Angiotensin II and K+

Zona Fasciculata - regulated by ACTH

Zona Reticularis - regulated by ACTH and “unknown factors”

41
Q

Everything made by each layer of the adrenal cortex requires what initial component?

A

Cholesterol

42
Q

Aldosterone release is regulated by…..

A

Renin-Angiotensin-Aldosterone system and plasma K+

Angiotensin II has both direct (vasoconstriction) and indirect (activation of aldosterone) effects on BP

43
Q

List some of the actions of Cortisol

A

Reduces serum calcium

Reduces wound healing and collagen formation

Reduces the immune/inflammatory response

Increases lipolysis and proteolysis

Causes an increase in blood glucose

Increases Cardiac output, BP and renal blood flow

44
Q

How does aldosterone affect the sodium/potassium balance?

A

Causes retention of Na+ and a loss of K+ (and also H+)

45
Q

What condition is Addison’s commonly misdiagnosed as?

A

Anorexia

46
Q

What is the most common cause of adrenal insufficiency in a) developed and b) developing countries?

A

Developed - Addison’s

Developing - adrenal TB, also HIV/AIDS

47
Q

Addison’s - treatment

A

Hormone replacement

Mineralocorticoids - Fludrocortisone

Glucocorticoids - Hydrocortisone

48
Q

How do you clinically tell the difference between someone with Addison’s and someone with secondary adrenal failure?

What is the most common cause of secondary adrenal failure?

A

Skin will be pale (as there is no raised ACTH)

Aldosterone production will also be intact

Most common cause of secondary adrenal failure is exogenous steroid use

49
Q

What is the most common cause of iatrogenic Cushing’s Syndrome?

A

Prolonged high-dose steroid therapy (e.g. asthma, RA, IBD, transplants)

Chronic suppression of ACTH results in adrenal atrophy

50
Q

What might be the diagnosis in a patient presenting with hypertension and hypokalaemia?

In what group of people would you specifically want to investigate high BP?

A

Conn’s Syndrome - primary hyperaldosteronism

90% of hypertension cases are ‘essential’ i.e. no apparent underlying cause. Investigate if the hypertension is persistent despite medications and the patient is young

51
Q

How is Conn’s Syndrome tested for?

A

Measure plasma aldosterone and renin levels and express as a ratio

If ratio is raised, investigate further with a saline suppression test - failure to suppress by more than 50% = hyperaldosteronism

Once confirmed, investigate subtype by performing adrenal CT

52
Q

What is the most common deficiency seen in Congenital Adrenal Hyperplasia?

How is it inherited?

A

21-Alpha-Hydroxylase (95% of cases)

Autosomal recessive

53
Q

What classical signs will someone with CAH present with?

A

Classically present with hirsutism in 20s and 30s

Also salt wasting, acne, oligomenorrhoea, infertility/sub-fertility

Males

  • adrenal insufficiency
  • poor weight gain
  • precocious puberty

Females

  • genital ambiguity
54
Q

In someone with CAH, what will lab studies show?

A

Hypoglycaemia (due to hypocortisolism)

Hyponatraemia (due to hypocortisolism)

Hyperkalaemia (due to hypoaldosteronism)

Elevated 17alpha-hydroxyprogesterone

55
Q

What is the classic triad of symptoms associated with a phaeochromocytoma?

A

Hypertension

Headaches

Sweating

56
Q

What % of patients with a hip fracture die within a year of the incident?

A

20%

57
Q

What is the most widely used measure of assessing bone density?

A

DEXA bone scans

58
Q

How are the following classed…

  • Osteopenia
  • Osteoporosis
  • Severe Osteoporosis
A

Osteopenia - bone mass density is between -1 and -2.5 of the standard deviation

Osteoporosis - bone mass density is equal to or less than -2.5 of the standard deviation

Severe osteoporosis - same as osteoporosis but with fragility fractures

59
Q

Was is the recommended amount of dietary calcium per day?

How does this change for post-menopausal women?

A

700mg a day

Post-menopausal women - 1000mg a day

60
Q

What drugs are available to help prevent fractures?

A

Bisphosphonates - most commonly used - slows down the breakdown of bone by inhibiting osteoclast activity (e.g. Alendronate, Risedronate)

Calcium and Vit D supplements

HRT

Denosumab

Teriparatide (recombinant form of PTH)

61
Q

What are some of the long-term concerns associated with bisphosphonate use?

A

Osteonecrosis of the jaw

Oesophageal cancer

Atypical fractures

62
Q

How does Teriparatide work?

A

Recombinant PTH - works to stimulate bone growth, rather than inhibit osteoclast activity

63
Q

Glucocorticoids have what effect on calcium?

A

Cause hypocalcaemia

Decreased Ca2+ absorption and increased Ca2+ excretion in the gut

Also affect the kidneys, pituitary and bone (reduces matrix synthesis resorption)

Hence why steroids cause osteoporosis

64
Q

What is Paget’s Disease of Bone?

How does it present clinically?

A

Abnormal osteoclastic activity followed by increased osteoblastic activity, resulting in reduced bone strength and increased risk of fracture.

Presents with bone pain, deformity, deafness or compression neuropathies

65
Q

What biochemical marker can be used to give an indication of osteoclast activity?

A

Alk Phos

66
Q

What genes are involved in Osteogenesis Imperfecta?

What is the classical clinical seen in a child?

A

Mutations of Type I collagen genes (COL1A1, COL1A2)

Child may present with blue-tinted sclera

67
Q

How is Relative Risk (also known as a risk ratio) calculated?

A

RR (exposed) = Incidence in exposed/Incidence in not exposed

68
Q

Which sinuses are closely related to the pituitary gland?

A

The sphenoid sinus

69
Q

The Left Recurrent Laryngeal Nerve hooks under ____

The Right Recurrent Laryngeal Nerve hooks under ____

A

Left - arch of the aorta

Right - Right subclavian artery

70
Q

How will diffuse causes of goitre (e.g. Grave’s, Thyroiditis) compare to focal causes (e.g. dominant nodule) on scintigraphy?

A

Scintigraphy assesses pattern and quantity of tracer uptake

Diffuse causes will show a generalised increase in uptake, while focal causes will show a “hot spot”

NB - in the case of TMN goitre, there may be general increased uptake with a dominant nodule causing a hotspot

71
Q

Describe briefly the physiology of PTH and its relationship to calcium

A

PTH is released from parathyroid glands…

Acts on the gut to increase absorption

Acts on the bones to increase resorption (increases activity and osteoclasts and decreases the activity of osteoblasts)

Acts on the kidneys to increase resorption

This results in an increase in serum Ca2+

Calcium-Sensing Receptors on the parathyroid gland then pick up this increase in serum calcium and switch off PTH release

72
Q

What is the active form of Vitamin D? Where is it produced?

A

Vitamin D is (mostly) taken in via the sun, converted to Cholecalciferol in the skin, then converted to 25 (OH) Vitamin D in the Liver, and then finally converted to it’s active form of 1,25 (OH) Vitamin D in the Kidneys (a.k.a. calcirtiol)

73
Q

Hypercalcaemia - symptoms

A

“stones, groans, bones and psychic moans”

Acute - thirst, dehydration, polyuria, confusion

Chronic - myopathy, osteopaenia, fractures, depression, hypertension, renal stones, pancreatitis

74
Q

Hypercalcaemia - causes

A

Hyperparathyroidism - main cause

Malignancy

Drugs - Vitamin D, thiazides

Granulomatous diseases - sarcoidosis, TB etc.

Famiilia Hypocalciuric Hypercalcaemia

75
Q

How is primary hyperparathyroidism diagnosed?

A
  1. Raised PTH (or inappropriately normal - should be low to negatively feed back)
  2. Raised Calcium
  3. Increased urinary calcium secretion
76
Q

How is hypercalcaemia treated?

A

Fluids

Consider diuretics once stable. NB - avoid thiazides

Bisphosphonates to lower Ca2+ (decreases osteoclast activity)

Steroids occasionally used

77
Q

What are the indications for surgery to treat primary hyperparathyroidism?

A

It’s either surgery or nothing!

  • End organ damage e.g. bone diseases, renal stones, gastric ulcers etc.
  • Very high serum Ca2+
  • under 50 years old
  • GFR <60 ml/min
78
Q

What are the causes of secondary and tertiary hyperparathyroidism? How do they differ to primary?

A

Secondary - caused by physiological response to low Calcium e.g. Vitamin D deficiency, renal disease, osteomalacia etc.

Secondary = low Ca2+, high PTH

Tertiary - occurs after many years of secondary, PTH becomes autonomous

Tertiary = high Ca2+, high PTH

79
Q

How can you differentiate between primary hyperparathyroidism and familial hypocalciuric hypercalcaemia clinically?

(clue is sort of in the name…)

How is FHH inherited?

A

Both will present with hypercalcaemia and raised PTH

However, FHH will present with LOWERED calcium in the urine, while primary hyperparathyroidism will raised calcium in the urine

FHH is autosomal dominant

80
Q

What are Trosseau sign and Chovstek sign? What do they indicate?

A

Trosseau - carpopedal spasm causing flexion at the MCPs, PIPs and DIPs

Chovstek - tapping over the facial nerve elicits a facial twitch

Both are signs of possible hypocalcaemia

81
Q

What are some of the causes of hypocalcaemia?

A

Chronic renal failure - most common cause

Vitamin D deficiency (osteomalacia, Rickets)

Hypoparathyroidism

82
Q

How is acute hypocalcaemia managed?

A

Medical emergency - treat with 10-10-10

IV calcium gluconate, 10 mls, 10% over 10 mins (in 50ml saline or dextrose)

83
Q

Which electrolyte is required to make PTH and, if low, may result in hypoparathyroidism?

A

Mg2+ is required to make PTH, and hypomagnesaemia may result in hypoparathyroidism

Magnesium is also required to release Ca2+ from cells, and so if magnesium is deficient this will result in high intracellular calcium = inhibition of PTH release

84
Q

What drugs might cause hypomagnesaemia?

A

(Alcohol)

Thiazide diuretics

PPIs

85
Q

Pseudohypoparathyroidism - cause and biochemical presentation

A

Genetic defect = GNAS1 (same as McCune-Albright)

Low Ca2+ but elevated PTH due to PTH resistance

86
Q

Pseudohypoparathyroidism - presentation

A

Bone abnormalities

Obesity

Subcutaneous calcification

Learning difficulties

Brachdactyly (4th metacarpal)

87
Q

What is pseudo-pseudohypoparathyroidism?

A

Same as pseudohypoparathyroidism, but with normal Ca2+

88
Q

Osteomalacia - clinical presentation

A

(NB - rickets = osteomalacia but in children)

Low Ca2+

Muscle wasting due to proximal myopathy

Dental defects

Tenderness, fractures, rib and limb deformities

89
Q

Hypoparathyroidism - causes

A

Congenital absence (DiGeorge’s syndrome)

Destruction (surgery, radiotherapy)

Autoimmune

Hypomangesaemia

Idiopathic

90
Q

Why does hypoparathyroidism result in a lack of Calcium?

A

No PTH = no resorption of Ca2+ from kidneys, gut and bone = low serum Ca2+

Year 2 - Endocrine (8 decks)

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