Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Paediatrics > Endocrinology > Flashcards

Endocrinology Flashcards

1
Q

What are the features + pathophysiology of Pendred syndrome?

A

Pathophysiology

  • SLC26A4 gene
  • Mutant anion transporter: pendrin
  • Pendrin usually transports iodide across the apical membrane of the thyrocte into the colloid space where it undergoes organification and incorporation into the tyrosine residues on thyroglobulin.

Features

  • Sensorineural hearing loss + goitre
  • MRI: enlarged vestibular aqueduct
  • Clinically euthyroid
  • Autosomal recessive
  • Goitre usually 75% in 2nd decade of life
  • Goitre worsens with iodine deficiency
  • Learning difficulties
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the x-ray features in vitamin D deficiency?

A
  • Earliest sign is usually osteopenia
  • Widening of the growth plate (physis); due to proliferation of uncalcified cartilage and osteoid
  • Metaphyseal widening, splaying, cupping + fraying
  • Coarse metaphyseal trabecular pattern
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is hypophosphatasia?

A
  • Hypophosphatasia is due to a deficiency of tissue nonspecific alkaline phosphatase.
    • ALP level = LOW
    • Does NOT respond to vitamin D
  • Perinatal form is universally lethal
  • Presentation
    • Marked hypomineralization of the bones, multiple fractures, and dysplasticvertebral bodies, which may be flattened, round, rectangular, or butterfly.
    • On prenatal ultrasound, characteristic findings include decreased skull echogenicity; short, bowed limbs; small thorax; and polyhydramnios.
    • The infantile form, which hasa slightly better prognosis than the perinatal form, has skeletal changes similar to rickets.
    • Multiple fractures, premature loss of childhood teeth, and short stature.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What regulates the release of GH + somatostatin?

A

GnRH

Somatostatin= growth hormone inhibiting hormone

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

Is the pituitary extra-dural or intra-dural?

A

EXTRADURAL

Not in contact with the CSF

Pituitary divided into: anterior (adenohypophysis) + posterior (neurohypophysis)

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

What is the origin of the anterior pituitary + posterior pituitary?

A

Anterior pituitary: derived from pharyngeal arches (Rathke’s pouch)

  • Craniopharyngiomas = permanent remnant between the connection between the Rathke pouch + the oral cavity

Posterior pituitary: outpouching of the brain

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

What do the following cell types release?

  • Somatotrophs (50% cells)
  • Lactotrophs (10-25% cells)
  • Thyrotrophs (10% cells)
  • Gonadotrophs (10-15% cells)
  • Corticotrophs (10-15% cells)
A
  • Somatotrophs (50% cells) = release human growth hormone
    • MOST sensitive cells in the pituitary therefore first to get destroyed
  • Lactotrophs (10-25% cells) = release prolactin
  • Thyrotrophs (10% cells) = release thyroid stimulating hormone
  • Gonadotrophs (10-15% cells) = release follicle stimulating hormone and lutenizing hormone
  • Corticotrophs (10-15% cells) = release of POMC (precursors of ACTH)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the most common cause of a goiter?

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

When is the most intense release of GH in children?

A

GH is released in a pulsatile fashion

Most intense period of GH release = within 1hr after the onset of deep sleep

GH secretion is lower in obese individuals

GH secretion is higher in females

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

Is GH produced anywhere else in the body?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What factors stimulate + inhibit the release of growth hormone?

A

Stimulation

  • GHRH
  • Ghrelin (produced in the stomach + hypothalamus)= hunger hormone
  • Hypoglycaemia
  • Deep sleep, exercise, stress, nutritional deficiency, estrogen or testosterone
  • Dopamine
  • Amino acids
  • High protein meals

Inhibition

  • Somatostatin
  • Hyperglycaemia
  • Leptin (released from fat)
  • Steroids
  • Hypothyroidism
  • GH and IGF1 (produced by the liver)– acts at the hypothalamus and pituitary as negative feedback
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does GH do?

A
  • Predominant action is to stimulate hepatic synthesis + secretion of IGF-1
  • Metabolic effects = opposes insulin action
    • Stimulates protein synthesis
    • Stimulates lipolysis
    • Antagonism of insulin
    • Phosphate, water + sodium retention
  • Anabolic effect= cartilage + bone growth
    • Stimulates linear growth (via synthesis of IGF-1)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where does FSH + LH act?

A

FSH: reduced by inhibin

  • Ovarian granulosa cells
  • Sertoli cells in testicles

LH: reduced by androgrens/oestrogens

  • Luteinisation of ovary
  • Leydig cells in testicles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is Pallister Hall syndrome?

A
  • Autosomal dominant
  • GL13 mutation = loss of function
  • Absence of pituitary gland
  • Hypothalaemic harmatoma
  • Polydactyly
  • Bifid uvula
  • Imperforate anus
  • Renal + heart abnormalities
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the best test of iodine deficiency?

A

Urinary iodine excretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does iodine deficiency + iodine excess cause?

A

Iodine deficiency

  • Causes hypothyroidism

Iodine excess

  • Causes hyperthyroidism OR hypothyroidism (Wolff-Chaikoff effect)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the commonest causes of congenital hypothroidism

WORLDWIDE

DEVELOPED COUNTRIES

A

WORLDWIDE = iodine deficiency

DEVELOPED COUNTRIES

  • Thyroid dysgenesis (agenesis, ectopic/lingual, hypoplasia)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How does the NST test for thyroid disease?

What are the problems?

A
  • NST ONLY detects HIGH TSH
  • Problems
    • 33% neonatal T4 is from mother therefore hypothyroidism may be missed
    • Only TSH elevation detected therefore wont detect;
      • Hyperthyroidism
      • Secondary / tertiary hypothyroidism
    • Premature babies have lower surge in TSH therefore can be false negative
      • Need to repeat test at 2-4 weeks of life
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do you see on bone age x-ray post birth in athyreosis?

A

No or small epiphyses seen at lower femoral or upper tibial areas on bilateral knee x-ray

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where is the most common site of ectopic thyroid tissue?

A

Lingual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Congenital hypothyroidism: dose adjustment problems

A
  • Potential problems with TSH setpoint
  • Children with athyreosis:
    • T4 can go into the hyperthyroid range even though TSH has not normalised
    • Adjust dose based on TSH levels even if T4 is “normal”
  • Overtreatment can potentially cause premature closure of the sutures (craniosynostosis); major complication of neonatal thyrotoxicosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the most common cause of hyperthyroidism in children + adolescents?

A

Grave’s disease

Most common autoantibody: TSHrAB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What levels of the following do you get in sick euthyroid?

TSH

T4

T3

rT3

A

TSH: low, normal or high

T4: normal or low

T3: LOW (due to reduced thyrozine-5’ deiodinase levels being reduced in illness which reduces the conversion of T4–> T3

rT3: HIGH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why do we avoid propylthiouracil in children?

A

Can cause liver failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the side effects of carbimazole?

A
  • Rash (15%)
  • GI disturbance
  • Cutis aplasia of scalp in neonates
  • Agranulocytosis
  • Neutropenia- dose related
  • Abnormal LFT’s
26
Q

What are the thyroi cancer syndromes?

A

FMTC

Familial MEN2a

  • AD RET gene
  • MTC, pheo, prim hyperparathyroidism, hirschprungs

Familial MEN2b

  • AD RET gene
  • MTC, pheo, mucosal neuromas, marfanoid

Gardner

  • Familial adenomatous polyps in the GIT + papillar thyroid cancer

Cowden / Proteus / Bannayan Riley Ruvalcaba (PTEN mutation)

  • AD harmatomas
  • Increased risk breast / endometrial / thyroid cancer

Werner: connective tissue disease

27
Q

What is the triad of hypopituitarism?

A
  • Hypoglycaemia
    • Loss of anti-insulin counter regulatory hormones
    • Delayed maturation of liver enzymes
    • GH, ACTH + TSH deficiency
  • Prolonged jaundice
    • Delayed maturation of liver enzymes
    • Giant cell hepatitis
    • TSH, GH, ACTH deficiency
  • Males- micropenis (<1.9cm in neonate) + underscended testes
    • GH + GnRH defiency
28
Q

What is septo-optic dysplasia (de Morsier’s syndrome)?

A

Midline defects

Septo- septum pellucidum may be absent

Optic- optic nerve hypoplasia

Hypopituituirism

Usually sporadic, 3 genes associated HESX1, PTX2, SOX2

29
Q

What are the heart defects associated with congenital hypothyroidism?

A

ASD, VSD, pulmonary stenosis

30
Q

What is growth hormone deficiency defined as on the stimulation test?

A

Patient must have evidence of biochemical growth hormone deficiency, with a peak serum growth hormone concentration less than 10 mU/L or less than or equal to 3.3 micrograms per litre in response to 2 pharmacological growth hormone stimulation tests (e.g. arginine, clonidine, glucagon, insulin)

31
Q

How do you investigate ACTH-Cortisol?

A
  • Morning cortisol
    • Low < 300 = hypopituitarism
    • Highest cortisol in the morning
  • ACTH level
    • Low or normal in hypopituitarism
  • Synacthen stimulation test
    • Low dose more sensitive if short synacten normal
32
Q

How do you adjust thyroxine dosing?

A

Aim to have the T4 in the upper limit of normal AND the TSH within normal range

33
Q

When should you cease thyroxine in neonates with suspected transient congenital hypothyroidism?

A

NOT until 3 years of age

34
Q

Why do you need to perform hearing tests in neonates with dyshormonogenesis

A
35
Q

Why do you perform a knee x-ray in neonates with congenital hypothyroidism?

A

Looking for absence of epiphyses which is suggestive of intrauterine hypothyroidism

36
Q

What are the genetic syndromes associated with Hashimoto’s?

A
  • Turner’s
  • T21
  • Klinefelter
  • IPEX
  • APS1 + APS2
37
Q

What is the most common cause of hyperthyroidisim in children?

A

Grave’s

38
Q

What are the common antibodies in Hashimoto’s?

A

TPO Ab + Anti Tg Abs 90% have one or both

Thyrotropin receptor blocking antibodies only ~ 10%

39
Q

Why can you get galactorrhoea + pseudoprecocious puberty in hypothyroidism?

A

In hypothyroidism you will have HIGH levels of TSH which can bind to the FSH receptor = stimulation

40
Q

What causes stare + lid lag in hyperthyroidism?

A

Sympathetic overactivity

41
Q

Is age of puberty + pubertal growth stages affecter by hyperthyroidism?

A

NO!

42
Q

What is the effect of hyperthyroidism on bones?

A

Causes osteoporosis due to thyroid hormones stimulating bone resorption

Serum ALP high + osteocalcin high

High serum calcium

43
Q

Who is at higher risk of Grave’s?

A

Females: males 5:1

Asians

HLAB8 + HLADR3

Addison’s

T1DM

Myasthenia Gravis

Celiac

Pernicious anaemia

Vitiligo

ITP

Psoriasis/ RA / alopecia

T21 + Turner’s

44
Q

What is the pathophysiology of Grave’s?

A

T helper cells become sensitive to TSH antigen –> T helper cells diffentiate –> plasma cells develop which produce TSH stimulating Ab —> binds to TSH receptor —> Activation —-> overproduction of thyroid hormones + diffuse glandular growth

45
Q

A TSH > 100 is usually due to…..

A

Athyreosis

OR

Defect in thyroid transcroption factor

46
Q

Central vs primary hypothyroidism

A

Central hypothyroidism : usually XLR or AR

  • Includes secondary (pituitary) + tertiary (hypothalamus) hypothyroidism
  • TSH inappropriately low, normal or slightly increased
  • FT4 low

Primary hypothyroidism

  • TSH high
  • FT4 low
47
Q

How do haemangioma’s cause hypothyroidism?

A
  • Haemangiomas can produce T4—> type 3 deiodinase (reverse T3) = inactive = clinical hypothyroidism
  • Can require extremely large doses of L-thyroxine
  • Condition resolves with regression of the haemangioma
48
Q

What is Pendred syndrome?

A
  • Autosomal recessive
  • Chromosome 7q 31
  • SLC26A4 gene which encodes an anion transported known as pendrin
  • Pendrin: transports iodide across the apical membrane of the thyrocyte into the colloid space
  • MRI: enlarged vestibular aqueduct syndrome
  • Clinically euthyroid, goitre WORSENS with iodine deficiency
49
Q

What are the signs and symptoms of a thyroid storm?

A

Use the Burch + Wartofsky criteria for the diagnosis of thyroid storm

  • High temp
  • CNS effects: seizures, coma, agitation, delirium, psychosis, lethargy
  • GIT: N/V/D, abdominal pain, jaundice
  • CVS: tachycardia/ heart failure/ AF
50
Q

What does dopamine inhibit?

A

Prolactin secretion

TRH/TSH response

51
Q

What is the pathophysiology of sick euthyroid syndrome?

A
  • Cytokine mediated
  • Reduced TRH release
  • Reduced TSH response
  • Reduced T4 production/ release
    • Very low fT4 values have a poor prognosis
  • Reduced T4 –>T3 production
  • Reduced TBG
  • Increased somatostatin secretion
52
Q

What HLA’s increase the risk of T1DM

A

HLA DR3 + DR4

53
Q

What is the pathophysiology of diabetes?

A

T cell mediated attack on target autoantigens in the islet beta cell

54
Q

What are the BSL targets in T1DM?

A

Pre-prandial: 4-8

Post prandial < 10

HbA1c <7.5%

55
Q

How do sulphonylureas work?

A

Sulphonylureas: gliclazide, glimepramide, glibenclamide

Increases insulin secretion by stimulating Beta cells

WIDELY used in MODY

DO NOT USE WITH INSULIN

56
Q

What is the mechanism of DPP-IV inhibitors?

A

DPP-IV inhibitors: sitagliptin

Stimulates incretins + reduced gastric emptying

Most effective at post prandial BGL reduction

Results in weight loss

57
Q

How do GLP-1 analogues work?

A

Stimulates incretins

Given via subcutaneous injection

Causes weight loss

Low risk of hypoglycaemia

NOT renally excreted

58
Q

What is permanent neonatal diabetes?

A
  • Heterozygous activating mutation in the KCNJ11 gene encoding Kir6.2 subunit of the pancreatic beta cell K ATP channel
  • Can also be associated with developmental delay, muscle weakness + epilepsy
  • Responsive to sulfonylureas
59
Q

What is Wolfram syndrome (DIDMOAD)?

A

Diabetes Insidious Diabetes Melitis Optic Atrophy + Deafness

WFS1 gene

Diabetes in infancy

Optic atrophy in childhood

60
Q

Definition of;

  • Gluconeogenesis
  • Glycogenolysis
  • Glycogenesis
  • Glycolysis
A

Definition of;

  • Gluconeogenesis= metabolic pathway resulting in production of glucose from non CHO substrates
    • 90% liver
    • 10% kidney
  • Glycogenolysis= breakdown of glycogen to glucose
  • Glycogenesis= formation of glycogen
  • Glycolysis= breakdown of glucose to generate ATP
61
Q

Glucose transport

  • Insulin INdependent
  • Insulin dependent
A
  • Insulin INdependent
    • GLUT1= brain
    • GLUT2= B islet cells, liver, kidney, small intestine
    • GLUT3= neurons
    • GLUT5= GIT
  • Insulin dependent
    • GLUT 4 = skeletal muscle + adipocytes
62
Q

What is the action of insulin?

A
  • Glucose transport in skeletal muscle + adipose tissue
  • Glycogen synthesis + storage
  • Triglyceride synthesis
  • Na+ retention in the kidneys
  • Protein synthesis
  • Fat synthesis + storage
  • Cellular uptake of K+ and amino acids
  • REDUCED glucagon release

Paediatrics (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions