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RACP EXAM > Endocrine > Flashcards

Endocrine Flashcards

1
Q

Name the 2 posterior pituitary hormones

A

ADH, Oxytocin

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2
Q

What hormones are released from the anterior pituitary

A

TSH, FSH, LH, GH, ACTH, Prolactin

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3
Q

What is the role of growth hormone

A

Induces targets to produce insulin-like growth hormone (IGF). IGF stimulates growth and increased metabolism

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4
Q

Where does ACTH stimulate and what does this cause

A

Adrenal gland. Increased secretion of glucocorticoids to regulate metabolism and stress response

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5
Q

A- Where is the Pituitary located

A

A- Sella Turcica/ pituitary fossa - directly behind the sphenoid air cells.

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6
Q

Anterior Pituitary
A- From where does the anterior pituitary develop
B- How are hormones stored and released
C- What hormones are released

A

A- Rathkes pouch, from an invagination of buccal mucosa / endoderm

B- Communication for release is via the hypothalamus. The hypothalamus releases neurotransmitters into the hypophyseal portal vessels which trigger release of hormone from the anterior pituitary

C-TSH, FSH/LH, ACTH, Prolactin, Growth hormone

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7
Q

Posterior Pituitary
A- Where does the posterior pituitary develop from
B- What hormones are released
C- Where are these hormones produced

A

A-Neural ectoderm- Consists of neurons that are extensions of the hypothalamus. Axons make up the stalk and the neutron terminates in the posterior pituitary lobe

B- ADH, Oxytocin

C- Supra-optic and paraventricular nuclei of the hypothalamus

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8
Q

What is the difference between a hormone that acts as an endocrine vs a paracrine vs autocrine

A

Endocrine- carried by the circulation to a distant site of action
Paracrine- direct effect on nearby cells
Autocrine- affect on the tissue that secrets it

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9
Q

HESX1 is a homeobox gene implicated in which disorder

A

Septo-optic dysplasia –> hypopituitary

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10
Q

Growth Hormone
A) Function
B) How does it generate growth promoting affects
C) Regulation

A

A: affects carbohydrate and lipid metabolism and growth promotion

B- Via IGF-1. GH binds to cell surface receptors which results in transcription of IGF-1. IGF-1 increases synthesis of DNA, RNA and proteins

C: Secretion is pulsatile. Nocturnal release occurs during slow-wave sleep. GHRH stimulates, Somatostatin inhibits growth hormone synthesis and release

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11
Q

Gonadotrophins- FSH + LH
A- Function of FSH
B- Function of LH
C- How is FSH/LH production stimulated
D- What hormone inhibits FSH/LH production

A

A- FSH: stimulates ovaries to mature follicles, binds to glomerulosa cells and stimulates conversion of testosterone to oestrogen. In males, binds to Sertoli cells in males to increase seminiferous tubules and support the development of sperm

B- Males- Stimulates leydig cells to produce testosterone. Females- binds to ovarian cells to stimulate steroidogenesis

C- Hypothalamus releases GnRH in pulsatile fashion –> stimulates production and release of FSH and LH from the hypothalamus

D- Inhibin

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12
Q

Thyroid stimulating Hormone:
A- Function
B- What regulates it

A

A- binds to cell receptors on thyroid follicular cells and activates adenylyl cyclase to cause production of thyroid hormone

B- Stimulated by TRH from hypothalamus. Inhibited by Thyroid hormone and Glucocorticoids

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13
Q

The precursor for ACTH gives rise to what other hormone

A

MSH- melanocyte stimulating hormone

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14
Q

In what order do you loose your pituitary hormones

A

GH
FSH/LH
TSH
ACTH

“Get Fizzed Tom A”

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15
Q

Name 3 genes associated with congenital hypopituitary

A

1- PROP1; most common cause of congenital multiple pituitary hormone deficiencies. Presents in growth failure at approx 6 years of age- deficient in Growth Hormone, Thyroid hormone, Prolactin, FSH and LH

2- PIT-1

3- HESX1- affects production of all anterior pituitary hormones. If homozygous, septa-optic dysplasia

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16
Q

What is Hall-Pallister Syndrome

What are the features

A

Absent pituitary gland + Hypothalamic Hamartoblastoma.

PALiSTER-HaL
-Pituitary failure
-Anus imperforate
-Limb abnormalities- polydactyl
-Skull- craniofacial abnormalities
-Throat- bifid oesophagus
-Epilepsy
-Renal Abnormalities

-Hypothalamic hamartoma
-Laryngeal cleft

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17
Q

CRANIOPHARYNGIOMA
A- What is it
B- What area of the pituitary does it affect
C- What classical visual symptoms due you get
D- What other symptoms can you get

A

A- A tumour arising from Rathke’s pouch

B- Anterior pituitary

C- Bitemporal hemianopia due to optic chiasm compression

D:
-Headache, temperature dysregulation,
-Hormone deficiency:
->GH: Growth failure
-> ADH: Diabetes insidious
-> ACT: Addison crisis (due to secondary adrenal failure) - hypoglycaemia, hyperkalaemia, hyponatreamia, hypotension, fever

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18
Q

What affect does hypoglycaemia have on growth hormone release

A

Stimulates its release

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19
Q

Which hormone inhibits the release of Prolactin

A

A- Dopamine

Dopamine antagonist, pituitary tumour, disruption of the pituitary stalk will cause increased PRL release –> lactation

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20
Q

Name 3 factors that stimulate ACTH production

When are ACTH levels highest

A

Stress, Fasting, Hypoglycaemia

Upon waking - secreted in a diurnal pattern

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21
Q

On which part of the renal tubule does ADH act

How does ADH work

What stimulates ADH release

A

Collecting duct

Stimulates the translocation of aquaporions. In high concentrations, it also stimulates smooth muscle cells

Increased plasma osmolality- perceived by osmo-receptors in the hypothalamus + reduced blood volume- sensed by baroreceptors in the aortic arch and carotid sinus

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22
Q

Which of the following does not stimulate GH secretion

A- Insulin
B- Glucagon
C- Dopamine
D- Arginine

A

C- Dopamine

Insulin, Glucagon and Arginine stimulate GH releasee

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23
Q

How do you perform a growth hormone stimulation test

A

Administer Glucagon/ insulin/Arginine –> measure level post –> GH <10 on 2x occasions is a positive test for deficiency

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24
Q

What are 4 contra-indications to giving growth hormone

A

OSA, Malignancy, Fanconi anaemia, IDDM

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25
Q

On average, how much does a child from between the ages of
A) 1-2
B) 2-4
C) 4- puberty
D) Puberty onward

A

A) 30-35cm
B) 7.5cm
C) 5cm
D 5-11cm

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26
Q

A) How do you calculate mid-parental height for a
BOY
GIRL

B) Above what cm different is a child not inkeeping with their genetic potential

A

BOY: (Father height + Mother height) +13 / 2

GIRL: (Father height + Mother height) -13 / 2

B) If >8.5cm above/below your mid parental height this is not in keeping with the genetic potential

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27
Q

What are the feature of Hall-Pallister syndrome

A

PALSTER-HaL”
-Pituitary failure. polydactyl
-anal imperforate
-lung abnormalities
-Skull- craniofacial abnormalities
-Throat- bifid oesophagus and tongue
-Epilepsy
-Renal abnormalities
-Hypothalamic hartoma
-Laryngeal cleft

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28
Q

What test is used to check for Growth hormone deficiency

A

GH stimulation test
Give insulin/glucagon/clonidine/arginine and test growth hormone for 2 hours to see if rises
If it doesn’t central GH deficiency

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29
Q

what are the side effects of growth hormone

A

T2DM
SUFE
Gynaecomastia
OSA
Benign intra-cranial HTN
Not used in cancers

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30
Q

SHOX gene is implicated in what
In what syndromes would you find more and less of it

A

SHOX= important for growth and expressed in chondrocytes.
Carries on the X and Y chromosome

Turner - less of it –> short
Klinefelters XXY –> too much of it –> tall

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31
Q

What is the abnormalities in Russel Silver syndrome
What are the symptoms

A

IGF-2 inappropriate methylation/ uniparental disomy etc

Sx; triangular face with large head, FTT, hemiatrophy, growth failure

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32
Q

What is the key difference between familiar short stature vs constitutional delay

A

Familial- normal growth velocity, bone age <1 separate year from chronological age, normal puberty onset, Final height short

Constitutional- bone age >1 year delayed from chronological age. Puberty delayed. Final height normal

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33
Q

NSD1 gene is implicated in what disorder

A

Soto syndrome

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34
Q

Soto syndrome
-what gene
-what sx

A

NSD1 gene
Sx: tall childhood growth velocity, frontal bossing, high arched palate, hypertelerosim, behavioural issues

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35
Q

What is the investigation for Diabetes Insipidus

A

Water deprivation test
-Keep testing until serum osmalaity >295
-failure to concentrate urine
-then give DDAVP
-If responds = central; if no response= nephrogenic

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36
Q

NDI gene on the X-chromosome is seen in what condition

A

Neonatal diabetes insipidus
Mutation of the V2 receptor –> congenital nephrogenic DI

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37
Q

What are nephrogenic causes of DI

A

Mutation at V2 receptor
Aquaporion mutation

Concentrating syndrome
-Bartter syndrome
-Gitteman Syndrome

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38
Q

What is inappropriately excreted in cerebral salt wasting
What effect does it have on
-blood pressure
-serum Na
-urine Na
-urine output

What is the treatment

A

ANP- atrial natureitic peptide
-Blood pressure: lower
-Blocks Aldosterone secretion –> lower sodium reabsorption –> reduced serum sodium
-urine sodium = very high
-urine output = very high

TX: IV Fluids with NaCl

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39
Q

What are causes of SIADH
What affect does it have on
-serum osmolality
-urine osmolality
-serum Na
-urine Na
-Blood pressure

What is the treatment

A

Infection- meningitis
Trauma
2nd part of recovery from neurosurgery (death of Anterior pituitary cells
Overdose of DDAVP

Serum osm: low
Urine osm: high
Serum Na: low
Urine sodium: relatively high
Blood pressure: normal

Fluid restrict
Salt replace
Urate crystals
Tolvaptin

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40
Q

What is the treatment of diabetes insipidus

A

Access to free water
Salt and protein restriction
Thiazide diuretic- trick proximal tubule to absorb more water
DDAVP

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41
Q

What features do you get in pseudohypoaldosteronism

What causes it

A

Signs of mineralocorticoid deficiency e.g. hyperkalaemia, hyponatraemia, hypotension
BUT high renin and high aldosterone

In true hypoaldosteronism get high renin but low aldosterone

Cause: loss of function mutation on sodium channel

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42
Q

What are the features of Liddles syndrome and why

What is the treatment

A

Liddles- gain of function mutation of epithelial sodium channel

Results in pseudohyperaldosteronism
-hypokalaemia, HTN
-metabolic alkalosis
-renin and aldosterone levels low

Treatment = aliloride which block the channel

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43
Q

what test would you order for paeochromocytoma

A

plasma noremetanephrine test

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44
Q

What do you get in
MEN III
MEN II
MEN I

A

MEN III:
-Medullary thyroid hyperplasia
-Medullary adrenal hyperplasia - phaeochromocytoma
-Mucosal neuroma

MEN II:
-Medullary thyroid neoplasm
-Medullary adrenal gland - phaeochromcytoma
-Parathyroid hyperplasia

MEN I
-parathyroid hyperplasia
-pituitary tumour
-pancrease carcinoma

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45
Q

What features do you get in 17OH deficiency

A

Cannot form cortisol and androgens. Only get androgen deficiency because deoxycortisone acts like cortisol.

Males= under-virilization
Female= lack of progress via puberty

Testing:
-reduced DHEA and androgen
-reduced cortisol
-increased ACTH

TX
-Hydrocortisone to reduce ACTH so not causing mineralocorticoid excess
-Testosteron/Oestrogen supplements

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46
Q

What occurs in a 3BHDH deficiency
What do you see on lab tests
What do you see externally

A

Cannot synthesis any elements in the cortex except DHEA
-deficiency in aldosterone, cortisol and androgens

Get
-low blood sugar, low blood pressure
-hyponatraemia, hyperkalaemia, metabolic acidosis
-increased renin and ACTH
-reduced Aldosterone and cholesterol
-increased DHEA

Males= undervirilisation + salt wasting
Females= may get mild virilization due to increased DHEA

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47
Q

What occurs in 21-OH deficiency
What do you see on labs
What do you see externally

A

Cannot form aldosterone and cortisol
Results in adrenal insufficiency of these areas and increased androgen production

Labs:
-increased DHEA, Androgen
-increased ACTH, reduced cortisol, no synacthen response
-increased Renin, reduced aldosterone, hyponatraemia, hyperkalaemia, metabolic acidosis, low blood pressure

External:
Female- virilzation of external genitalia
Male- no affect- present in crisis due to salt wasting and lack of cortisol response in stress

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48
Q

What occurs in a 11-B OH deficiency
What occurs in lab
What do you see symptomatically

A

Cannot form Cortisol only. Nil issues with mineralocorticoids or androgens

Labs:
-increased ACTH, reduced cortisol, nil response to synacthen
-Slightly increased androgens
-Normal renin and aldosterone as renin regulates this pathway
-INCREASED DEHYDROXYCORTISOL

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49
Q

What are the zones of the adrenal cortex and what do they produce

A

Zona Granulosa- Mineralocorticoids
Zona Fasciculata- Glucocorticoids
Zona Reticularis - Androgens

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50
Q

What age is the adrenal gland made
when does it begin steroid production

A

8 weeks
9-12 weeks

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51
Q

What are the features of McCunes Albright syndrome

A

Coast of Maine birth spot
Fibrous dysplasia
Endocrine hyperfunction e.g. oestrogen producting cysts, hyperfunction of adrenal gland

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52
Q

What test helps differentiate primary vs secondary Cushings syndrome

A

Dexamethasone suppression test
-Give 11pm dose of dexamethasone
-should suppress ACTH secretion
-check cortisol mane
-if reduced cortisol, secondary causes (pituitary adenoma secreting ACTH)
-if nil change to cortisol, ACTH independent lesion e.g. adrenal adenoma

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53
Q

When is the best time in cushings to check a cortisol level

A

midnight- reverse of normal cortisol peak elevation

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54
Q

What is conns syndrome

A

Aldosterone secreting adrenal tumour

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55
Q

How do you investigation primary vs secondary adrenal insufficiency

A

Short Synacthen test

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56
Q

What is an adrenal crisis

A

Decompensation due to hypo functioning adrenal system in context of a stressor

-Cortisol: low BSL, hypotension
-Aldosterone: hyperkalaemia, hyponatraemia, hypotension, metabolic acidosis

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57
Q

What are 4 causes of hyperaldosteronism

A

-Conns syndrome
-Renal artery stenosis
-Renin secreting tumour
-Reduced ECF volume e.g. nephrotic syndrome

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58
Q

DAX1 mutation is seen in what

A

congenital adrenal hypoplasia

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59
Q

What is a STAR mutation and what is the result

A

Affects cholesterol uptake in to the adrenal gland
Nil uptake -> nil dyshormogenesis

In males, results in undervirilization
In both causes salt wasting and cortisol deficiency

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60
Q

What is given to stop idiopathic central precocious puberty

A

GnRH - Lucrin - stops pulsatile GnRH so FSH and LH are secreted

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61
Q

How do you differentiate peripheral vs central precocious puberty

A

GnRH stimulation test
-in central you get a LH increase
-in peripheral you do not

62
Q

what are the features of Kallman syndrome
How is it inherited
Why does it occur

A

Anosmia
Microphalus
Cryptoorchidism - hypogonadotrophic hypogonadism
Midline facial abnormalities

X-linked

Neuronal migration issue for olfactory and GnRH secreting neurons

63
Q

what hormones would you check to look for testicular cell function

A

AMH and Inhibin B

64
Q

what test do you perform to see if the testicles are capable of secreting testosterone

A

HCG stimulation test

65
Q

How does GnRH FSH and LH differentiate thelarche vs central puberty

A

FSH dominant response in thelarch
LH dominant response in central puberty

66
Q

what is the treatment for McCune Albright

A

oestrogen blocker- tamoxifen
aromatase inhibitor - anastrozole, letrozole

67
Q

what do these tests show about testicular function
-hCG stimulation test
-Inhibin B
-AMH

A

hCG: reveal functional leydig cells. hCG stimulates LH receptors on Leydig cells to stimulate testosterone production

Inhibin B: made be Sertoli cells (and germ cells in puberty). Assesses presence of functional sertoli cells
Inhibits FSH secretion

AMH: secreted until puberty. marker of Sertoli cell function

68
Q

What is IPEX
What causes it

A

Immune dysfunction polyendocrinopathy X-linked

Mutation of a gene that controls T-regulator cells

69
Q

What are the symptoms of Autoimmune Poly-endocrinopathy type 1

A

Hypoparathyroidisim
Addisons disease
Mucocutaneous candititis

70
Q

What are the 3 auto-antibodies in diabetes
What order do they appear

A

anti glutamic acid decarboxylase (anti-GAD)
Anti insulin associated antigen (anti-IAAS)
Anti-islet antiget (Anti-IA2)

IAAS is the first to occur
Followed by anti-GAD

71
Q

When giving subcut insulin to a mild DKA new diagnosis
what units/kg do you give for a pre-pubescent vs pubescent child

A

pre-pubescent: 0.5-1.2unit/kg/day
pubescent: 0.7-1.5units/kg/day

72
Q

What type of insulin is Humulin R and Actrapid
How long is their duration

A

Short active
Onset within 30min
Peak: 3 hours
Duration- 8 hours

73
Q

what type of insulin is protophane? how long is its duration
when is its peak

A

Intermediate acting
16 hours
peak 4-10 hours

74
Q

what type of insulin is insulin-glargine
what is its duration

A

Lantus- long acting
24 hour duration
No peak

75
Q

What is another name for Humalog insulin lispro

A

nova rapid

76
Q

What type of insulin is Humulin NPH
Duration of action?
Peak?

A

Intermediate
Also known as protaphane

16 hours
Peak= 4-10 hours

77
Q

what is the recommended k-calorie intake for a diabetic

what % is carbs/protein/fat

A

1000kCal + 100kCal per year of age

50% carbs
30% fat
20% protein

78
Q

what is the somogyi phenomenon

A

hyperglycaemia ==> early night hypoglycaemia due to overshoot of anti insulin hormones in a child with well controlled diabetes

management = reduce night time insulin

79
Q

what is the mechanism of action of metformin
how does it work
what are the side effects

A

increased AMPK protein kinases

Stops liver Gluconeogenesis
Stops GI absorption of glucose
Increases peripheral sensitivity to insulin

S/E
=GI upset
=Lactic acidosis as lactic acid cannot enter Gluconeogenesis in the liver

80
Q

How do SLGT2 inhibitors work
What are the side effects

A

Block sodium/glucose reabsorption in the proximal tubule
Result = increased glucose loss in the urine so better serum glucose.Also causes osmotic diuresis = better blood pressure = better renal protection

S/E
-Euglycaemia DKA
-Vaginal candititis
-UTI
-Infection in genital region –> necrotising fascities
-Hypovolaemia especially if on ACE inhibitor or diuretic

81
Q

What is the mechanism of action of GLP-1 mediation
How does that work in the body

What is at the end of their drug name
What side effects

A

Glucagon like peptide agonist
Bind to glucagon receptors

-In pancreas, increase insulin secretion, reduce glucagon secretion
-Liver: reduced gluconeogeneis
-Peripheries: increased sensitivity to glucose
-reduced gastric emptying and reduce appetite to trigger weight loss

“Glutide”

S/E: nausea, vomitting, diarrhoea

82
Q

how do GPP-4 medications work in diabetes

A

Bind to enzymes to stop the break down of GLP - glucagon like peptide and and GIP-gastric inhibitory peptide (stimulates insulin secretion)

83
Q

What defects do you see in
MODY1
MODY2
MODY3
MODY4
MODY5

What treatment is needed for
MODY2 and MODY3
What is the difference in their proinsulin: insulin ration

What is the most common form of MODY

A

MODY1: HFN-4a
MODY2: Glucokinase
MODY3: HFN-1a
MODY4: IPF1
MODY5- HNF-1b

Mody 2= no treatment. Results in slightly higher baseline for insulin release but released once BSL>7. No deterioration. No microvascular complications

Mody 3: sulfonurea and then eventually insulin. Results from impaired transcription of potassium channel and insulin

Mody2= normal pro-insulin : insulin
Mody 3= increased pro-insulin: insulin

MODY3

84
Q

Where does the thyroid gland form from
What gestation does it migrate to the neck

A

Floor of the pharynx- a midline out pouch from the buccal cavity

Week 7

85
Q

Why is a foetus at risk of a hypothyroid mother

A

1/3 of maternal T4 crosses the placenta. Thyroid hormone is essential for brain development
Fetus doesn’t start production until approx 10-12 weeks with risk in levels from mid-gestation
Therefore reliant on maternal thyroid hormone

86
Q

why is it important to test thyroid hormone on a Guthrie on day 3 onwards

A

Cord clamping and cold stress cause a surge in TSH. This falls after 24 hours

If tested early, can cause false positive if tested before TSH surge has stopped

87
Q

Describe thyroid hormone synthesis

A

TRH binds to a G-protein coupled receptor on the thyroid follicle.
Stimulates increased intra-cellular cAMP
Leads to increased transcription of thyroglobulin
Thyroglobuin then passes into the colloid of the cell

Na/I cotransporter uptake iodide from the cell
Iodide is pumped into the colloid via a Cl-/Iodine transporter

The enzyme PERIOXIDASE converts iodide to iodine
Iodine binds to tyrosin rings on the thyroglobulin molecule
-1 iodine molecule = monoiodinetyrosin (MIT)
-2 iodine = diiodinetyrosin (DIT)

MIT+DIT = T3
DIT + DIT= T4

-Thyroglobin and MIT/DIT structure then is taken back into the follicle cell by pinocytosis
-Lysosomes break the thyroglobin off to release molecules of T3 and T4
-Iodine is recycled also to allow the process to be repeated

88
Q

what is the role of thyroid peroxidase in thyroid hormone production

A

converts iodide –> iodine
allows organification by the binding of iodine to thyroglobin tyrosine molecules

89
Q

in. radioactive thyroid scan what does a hot scan vs cold scan show

A

-hot scan: increased uptake due to increased thyroid hormone production = thyroiditis, graves

-cold scan= area of reduced uptake. carcinoma until proven otherwise

90
Q

what is the most common cause of thyroid dysgenesis

A

ectopic thyroid gland

91
Q

what causes a goitre in primary hypothyroidism due to dyshormonogenesis

A

increased TSH production

92
Q

what is the most common enzyme implicated in dyshormonogensis

what is the result

A

thyroid peroxidase
unable to iodinate thyroglobulin

93
Q

what is Fanconi-bickle syndrome

A

GLUT 2 mutation so glucose is not released from the liver or nephrons

Results in hepatomegaly and eventually proximal tubular nephropathy
Get short stature

94
Q

What is DEND syndrome

A

KCNJ11 mutation causing epilepsy, neonatal hypoglycaemia and developmental delay

95
Q

KCNJ11 mutation is implicated in what disease

A

DEND syndrome- epilepsy/neonatal hypoglycaemia/developmental delay

96
Q

what differentiates thyroid hormone resistance from Graves disease

A

Graves you get suppression of the TSH

In thyroid hormone resistance the pituitary is also resistance to thyroid hormone so doesn’t’ recognise it ==> elevated TSH without evidence of hyperthyroidism

97
Q

what occurs in fetal congenital hypothyroidism

A

maternal IgG antibodies bind to TSH receptors and block them
Result - lack of T3 and TSH production, increased TSH

98
Q

in fetal congenital hypothyroidism how long does maternal IgG last
When does it resolve by

A

21 days

2-3 months

99
Q

what does neonatal screening for congenital hypothyroidism screen

what does it miss

A

TSH

Will miss central causes of hypothyroidism as won’t get increased TSH e.g. from pituitary or hypothalamic dysfunction

100
Q

If there is no uptake of radionucleiotide scan but a normal gland on ultrasound what is the next test

A

DDX: TSH receptor blocking antibodies OR TSH resistance

TSH receptor antibody levels

101
Q

When starting levothyroxine how often do you monitor level

A

Weekly for first 4 weeks
Then monthly until 12 months
Then 2 monthly until 24 months
Then 3 monthly

102
Q

Name 5 causes of hypothyroidism

A

1) Central- pituitary/hypothalamic dysfunction
2) Congenital
-dysgenesis of the gland
-disorder of hormonogensis
-Thyroid hormone resistance
3) Autoimmunie
- Hashimotos
4) Alloimmune
-maternal IgG antibodies blocking TSH receptors
5) External
-iodine deficiency
-phenytonin, phenobarbital, valporate
-amiodarone

103
Q

what drugs cause hypothyroidism

A

-phenytonin, phenobarbital, valporate
-lithium
-amiodarone

104
Q

Name 5 causes of hyperthyroidism

A

1) Autoimmune
-Graves disease
2) Congenital
-Thyrotropin receptor activating mutation
3) Drugs:
-iodine, contrast
-amiodarone
4) Cancer: toxic adenoma
5) External
-McCune Albright syndrome

105
Q

In what % of children with Down and Turner develop anti-thyroid antibodies

A

30-40%

106
Q

what is the half life of levothyroxine
how long until it reaches steady state

A

6 days
3.5 weeks

107
Q

how does carbimazole work

A

blocked the thyroid peroxidase enzyme

108
Q

what antibodies cause hashimotos

A

anti-thyroglobin
anti-perioxidase (anti-TPO)

109
Q

what type of hypersensitivity reaction is hashimotors

A

Type 4 - activated CD8 cells which have been recruited by B-cells responding to a antigen they are hypersensitive to

110
Q

Describe autoimmune polyendocrinopathy type 1 and type 2

A

Type 1= HAM
hypopituitary, Addisons, mucocanditis

Type 2= HAD
-Hashimotos, adrenal insufficiency, diabetes

111
Q

what would you see on radio iodide scan in Hashimotos

A

patchy irregular uptake

112
Q

Name 5 causes of hyperthyroidism

A

-central hypopituitary tumour
-autoimmune: graves
-alloimmune: maternal graves disease
-cancer: solitary adenoma, toxic multi-nodular goitre
-inflammation: thyroiditis
-iatrogen: excess intake of levothyroxine, contract
-syndrome: McCune albright

113
Q

hyperthyroid + diffuse goitre=

A

graves disease

114
Q

what is the physiology of graves disease

A

B-cell produced anti-bodies mimic the TSH molecule and can bind to the TSH receptor, up regulating thyroid production

T3 and T4 increase
Negative feedback on the HPA axis so TSH is suppressed

115
Q

Why do you get eye and skin and muscle signs in hyperthyroidism

A

antibodies are not unique to the TSH receptor
Also bind to the eyes and legs
Result
-proptosis + opthalmoplegia
-skin: myxoedema
-muscle: wasting
as body attacks itself in this manner with lymphocyte infiltration

116
Q

What antibodies do you see in Graves disease

A

Thyrotropin receptor stimulating antibodies

117
Q

what test is used to assess for the presence of ectopic thyroid tissue

A

scintigraphy

118
Q

what is the best measure of thyroid function when treating congenital primary hypothyroidism to ensure normal development

A

TSH- most sensitive marker

119
Q

What are some foods/minerals that interfere with levothyroxine absorption

A

soy
iron
calcium
antacids

120
Q

when is secretion of TSH highest

A

At night

121
Q

A child has high TSH and low T3 and T4
You check autoantibodies by these are negative

-what antibodies do you check
-what is your differential diagnosis

A

Anti-TPO
Anti-Thyroglobulin

Iodine deficiency
thyroid injury
CH
Liver haemangiomas

122
Q

A child has symptoms of hyperthyroidism with a low TSH and high T3 and T4

-what antibodies do you order
-if these are negative what is your differential

A

TSI and TPO

If TSI and anti TPO increased: Graves
If TSI low and increased TPO/anti-TG= autoimmune thyroiditis

If both negative- nodule or drug induced

123
Q

What is the reason PTU (Propylthiouracil) is not used in children except for in adolescents during pregnancy

What other side effects does it have

A

Hepatotoxicity
Transient Granulocytopenia

124
Q

What is Carbimazoles MoA
How long does it take to work
What is used in conjunction

A

Blocks thyrohomonogensis by blocking thyroid perioxidase
Onset-6-8 weeks

B-blockers used to reduce tachycardia and act as peripheral blockers by reducing the conversion of T4 –> T3

ADR
-agraulocytosis
-liver failure
-urticaria, myalgia

125
Q

After thyroid removal, development of a hoarse voice is due to damage of what nerve

A

Recurrent laryngeal nerve

126
Q

what percentage of children with graves achieve remission

A

25%

127
Q

what monoclonal antibody can be used in thyroid eye disease

A

teprotumumab

128
Q

Why do you get a thyroid storm
What is treatment

A

Thyroxine potentiates catecholamines –> tachycardia, fever, restlessness, heart failure

Can be triggered by infection, trauma, surgery

TX
-Propythiouracil - used as faster onset and stops peripheral T4 -> T3 conversion
-Propanolol
-Steroids
-Cooling cares

128
Q

Why do you get a thyroid storm
What is treatment

A

Thyroxine potentiates catecholamines –> tachycardia, fever, restlessness, heart failure

Can be triggered by infection, trauma, surgery

TX
-Propythiouracil - used as faster onset and stops peripheral T4 -> T3 conversion
-Propanolol
-Steroids
-Cooling cares

129
Q

in what areas of the nephron do calcitrol and PTH work

A

Calcitriol works in the proximal convoluted tubule

PTH works in the distal convoluted tubule

130
Q

what gland makes calcitonin

A

thyroid gland

131
Q

how does calcitriol work

A

inhibits bone resorption
works with GI hormones to inhibit GI absorption of calcium

132
Q

what affect does PTH have on bone

A

PTH binds to osteoblasts which triggers them to stop proliferating and express RANK-L. RANK-L binds to the RANK receptor on a pre-osteoblast. This Triggers pre-osteoclast proliferation + maturation -> release acid which breaks down bone causing bone resorption.

Minerals leave the bone

133
Q

what enzyme in the kidney does PTH upregulate
what does this do

A

a-1 hydroxylase
Increased conversion of calcidiol to calcitriol

134
Q

what affect does PTH have on phosphate

A

stimulates phosphate excretion to prevent hyperphosphataemia as a result of bone resorption

135
Q

what are the symptoms of hypercalcaemia

A

bone ache
renal stones
abdomen pain
behavioural changes

136
Q

what are 2 important causes of secondary hyperparathyroidism

A

-renal loss - unable to resorb calcium = low serum levels = chronically elevated PTH

-Nutritional deficiency in Vitamin D

137
Q

What do you see with calcium and phosphate with hypoparathyrodism

A

low calcium
high phosphate

138
Q

what is the precursor molecule of cholecalciferol

A

7-dehydrocholesterol

139
Q

what occurs in Vitamin D toxicity

A

Hypercalcaemia

140
Q

What is rickets
what are the sx

A

a disease of under mineralised bone at the growth plates

Developmental delay
Easy fractures
-Head: Frontal bossing, delayed fontanelle closure, delayed dentition, softened cranial bones (craniotabes)
-Chest: rachitic rosary, harrisons sulcus
-Limbs: bowing of tibia, valgus or various deformity

141
Q

what features on investigation would you see in Vitamin D deficiency

A

Low serum calcium
High PTH
Low serum phosphate
Low calcidiol or calcitriol

142
Q

What is Vitamin D dependent Rickets Type 1

What is the treatment

A

defect of a-1-OH
Cannot convert calcidiol -> calcitriol

Calcitriol

143
Q

What is Vitamin D dependent Rickets Type 2

What is the treatment

A

Mutation of calcitriol so calcitriol doesn’t work

Need IV calcium infusion OR if partial function very high dose calcitriol

144
Q

What is the relationship between magnesium and PTH

A

Hypomagnesium = reduced release of PTH (blunts its response)

HYPOMAGNESIUM CAUSES HYPOCALCAEMIA

145
Q

PHEX gene defect is seen in what condition

A

Vitamin D resistant rickets
-PHEX mutation = increased FGF23
-FGF23 inhibits a1-OH resulting in reduced calcitriol
-FGF-23 reduces renal reabsorption of phosphate –> hypophosphataemia

146
Q

What affect does hypophosphataemia have on calcitriol

A

calcitriol production is INCREASED secondary to hypophosphataemia

147
Q

what would be causes for hypocalcaemia + a high PTH

A

-making PTH but calcium is not being absorbed
-Vitamin D deficiency
-renal loss
-GI malabsorption
-Pseudohypoparathyrodism (tissue resistance to PTH)

148
Q

What forms of osteogenesis imperfect have blue sclera

What type is fatal

What types have the most severe phenotype

Why do they get hearing loss

A

Types 1 + 2

Type 2

Types 2 + 3

Otosclerosis

149
Q

what gives sclera in osteogenesis imperfect the blue appearance

A

partial visualisation of the choroid

150
Q

what is the MoA of diaoxide in neonatal hypoglycaemia

A

Diazoxide opens ATP-dependent potassium channels on pancreatic beta cells in the presence of ATP and Mg2+, resulting in hyperpolarization of the cell and inhibition of insulin release. Diazoxide binds to a different site on the potassium channel than the sulfonylureas.

151
Q

what do parafollicular cells produce

A

also known as C-cells
Calcitonin

RACP EXAM (9 decks)

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