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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
Congenital thyroid disease in the young - presentation
**Jaundice** is the most common symptom Poor feeding but "normal" weight gain Hypotonia ("floppy baby syndrome") Skin and hair changes
26
How is congenital thyroid disease screened for? When is this done? Why?
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
27
What does continued absence of thyroxine in a baby result in?
Absence of thyroxine after 3 months of life leads to global developmental delay - **cretinism**
28
What is the most common cause of acquired thyroid disease in the young? What are some of the other causes?
Most common cause - **autoimmune** Other causes - post-infectious, delayed congenital, iodine deficiency
29
How do hypo and hyperthyroidism present in the young?
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
30
How would virilisation as a result of Congenital Adrenal Hyperplasia (and therefore excess testosterone) present in a) boys and b) girls
Boys - precocious puberty Girls - ambiguous genitalia
31
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?
**Hyponatraemia** **Hyperkalaemia** **Hypotension**
32
During development, what are the names of the male and female ducts? What causes the regression of each? How is this affected by CAH?
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
33
How are a) monogenic disorders and b) polygenic disorders best evaluated?
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)
34
MEN1 and MEN2 defects are classic examples of (monogenic/polygenic) disorders Can you name some more?
Monogenic McCune-Albright Carney Complex Von-Hippel Lindau disease Neurofibromatosis type I
35
Defects in which genes cause the following conditions? - MEN1 - MEN2 - McCune-Albright - Carney complex - Von-Hippel Lindau - Neurofibromatosis type I
MEN1 - **MEN1 gene** MEN2 - **RET gene** McCune-Albright - **GNAS1 gene** Carney Complex - **PRKAR1A gene** Von-Hippel Lindau - **VHL gene** Neurofibromatosis I - **NF1**
36
How do MEN1 and MEN2 disorders differ in terms of requirements for pathology to occur?
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
37
What conditions are the different MEN disorders assocaited with?
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
How might someone with McCune-Albright syndrome present clinically?
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
The mutation seen in Von-Hippel Lindau is (autosomal dominant/autosomal recessive)
**Autosomal dominant**
40
What regulates each layer of the adrenal cortex?
Zona Glomerulosa - regulated by **Angiotensin II and K+** Zona Fasciculata - regulated by **ACTH** Zona Reticularis - regulated by **ACTH** and "unknown factors"
41
Everything made by each layer of the adrenal cortex requires what initial component?
**Cholesterol**
42
Aldosterone release is regulated by.....
Renin-Angiotensin-Aldosterone system and plasma K+ Angiotensin II has both direct (vasoconstriction) and indirect (activation of aldosterone) effects on BP
43
List some of the actions of Cortisol
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
How does aldosterone affect the sodium/potassium balance?
Causes **retention of Na+** and a **loss of K+ (and also H+)**
45
What condition is Addison's commonly misdiagnosed as?
Anorexia
46
What is the most common cause of adrenal insufficiency in a) developed and b) developing countries?
Developed - Addison's Developing - adrenal TB, also HIV/AIDS
47
Addison's - treatment
Hormone replacement Mineralocorticoids - **Fludrocortisone** Glucocorticoids - **Hydrocortisone**
48
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?
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
What is the most common cause of _iatrogenic Cushing's Syndrome?_
**Prolonged high-dose steroid therapy** (e.g. asthma, RA, IBD, transplants) Chronic suppression of ACTH results in adrenal atrophy
50
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?
**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
How is Conn's Syndrome tested for?
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
What is the most common deficiency seen in Congenital Adrenal Hyperplasia? How is it inherited?
**21-Alpha-Hydroxylase** (95% of cases) Autosomal recessive
53
What classical signs will someone with CAH present with?
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
In someone with CAH, what will lab studies show?
Hypoglycaemia (due to hypocortisolism) Hyponatraemia (due to hypocortisolism) Hyperkalaemia (due to hypoaldosteronism) Elevated **17alpha-hydroxyprogesterone**
55
What is the classic triad of symptoms associated with a phaeochromocytoma?
Hypertension Headaches Sweating
56
What % of patients with a hip fracture die within a year of the incident?
20%
57
What is the most widely used measure of assessing bone density?
DEXA bone scans
58
How are the following classed... - Osteopenia - Osteoporosis - Severe Osteoporosis
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
Was is the recommended amount of dietary calcium per day? How does this change for post-menopausal women?
**700mg** a day Post-menopausal women - **1000mg** a day
60
What drugs are available to help prevent fractures?
**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
What are some of the long-term concerns associated with bisphosphonate use?
Osteonecrosis of the jaw Oesophageal cancer Atypical fractures
62
How does Teriparatide work?
Recombinant PTH - works to stimulate bone growth, rather than inhibit osteoclast activity
63
Glucocorticoids have what effect on calcium?
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
What is Paget's Disease of Bone? How does it present clinically?
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
What biochemical marker can be used to give an indication of osteoclast activity?
**Alk Phos**
66
What genes are involved in Osteogenesis Imperfecta? What is the classical clinical seen in a child?
Mutations of Type I collagen genes (**COL1A1, COL1A2**) Child may present with **blue-tinted sclera**
67
How is Relative Risk (also known as a risk ratio) calculated?
RR (exposed) = Incidence in exposed/Incidence in not exposed
68
Which sinuses are closely related to the pituitary gland?
The **sphenoid sinus**
69
The Left Recurrent Laryngeal Nerve hooks under \_\_\_\_ The Right Recurrent Laryngeal Nerve hooks under \_\_\_\_
Left - arch of the aorta Right - Right subclavian artery
70
How will diffuse causes of goitre (e.g. Grave's, Thyroiditis) compare to focal causes (e.g. dominant nodule) on scintigraphy?
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
Describe briefly the physiology of PTH and its relationship to calcium
PTH is released from parathyroid glands... Acts on the gut to **increase** **ab****sorption** 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
What is the active form of Vitamin D? Where is it produced?
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
Hypercalcaemia - symptoms
"stones, groans, bones and psychic moans" Acute - thirst, dehydration, polyuria, confusion Chronic - myopathy, osteopaenia, fractures, depression, hypertension, renal stones, pancreatitis
74
Hypercalcaemia - causes
**Hyperparathyroidism** - main cause Malignancy Drugs - Vitamin D, thiazides Granulomatous diseases - sarcoidosis, TB etc. Famiilia Hypocalciuric Hypercalcaemia
75
How is _primary_ hyperparathyroidism diagnosed?
1. Raised PTH (or inappropriately normal - should be low to negatively feed back) 2. Raised Calcium 3. Increased urinary calcium secretion
76
How is hypercalcaemia treated?
Fluids Consider diuretics once stable. **NB - avoid thiazides** Bisphosphonates to lower Ca2+ (decreases osteoclast activity) Steroids occasionally used
77
What are the indications for surgery to treat primary hyperparathyroidism?
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
What are the causes of secondary and tertiary hyperparathyroidism? How do they differ to primary?
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
How can you differentiate between primary hyperparathyroidism and familial hypocalciuric hypercalcaemia clinically? (clue is sort of in the name...) How is FHH inherited?
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
What are Trosseau sign and Chovstek sign? What do they indicate?
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
What are some of the causes of hypocalcaemia?
**Chronic renal failure** - most common cause Vitamin D deficiency (osteomalacia, Rickets) Hypoparathyroidism
82
How is acute hypocalcaemia managed?
Medical emergency - treat with **10-10-10** IV calcium gluconate, **10 mls**, **10% over 10 mins** (in 50ml saline or dextrose)
83
Which electrolyte is required to make PTH and, if low, may result in hypoparathyroidism?
**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
What drugs might cause hypomagnesaemia?
(Alcohol) Thiazide diuretics PPIs
85
Pseudohypoparathyroidism - cause and biochemical presentation
**Genetic defect = GNAS1** (same as McCune-Albright) Low Ca2+ but elevated PTH due to **PTH resistance**
86
Pseudohypoparathyroidism - presentation
Bone abnormalities Obesity Subcutaneous calcification Learning difficulties Brachdactyly (4th metacarpal)
87
What is pseudo-pseudohypoparathyroidism?
Same as pseudohypoparathyroidism, but with normal Ca2+
88
Osteomalacia - clinical presentation
(NB - rickets = osteomalacia but in children) Low Ca2+ Muscle wasting due to proximal myopathy Dental defects Tenderness, fractures, rib and limb deformities
89
Hypoparathyroidism - causes
Congenital absence (DiGeorge's syndrome) Destruction (surgery, radiotherapy) Autoimmune Hypomangesaemia Idiopathic
90
Why does hypoparathyroidism result in a lack of Calcium?
No PTH = no resorption of Ca2+ from kidneys, gut and bone = low serum Ca2+

Year 2 - Endocrine (8 decks)

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