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Endocrinology > Hyper/Hypo - Thyroidism > Flashcards

Hyper/Hypo - Thyroidism Flashcards

1
Q

Where is TSH produced?

A

Anterior pituitary

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2
Q

How does T3 and T4 travel in the blood?

A

In the plasma bound to a protein, TBG

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3
Q

What is the structure of the thyroid gland?

A

Lies against and around front larynx and trachea, below thyroid cartilage

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4
Q

What is the majority of the thyroid hormone circulating in the blood?

A

T4

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5
Q

What protein is needed to make T3 and T4?

A

Tyrosine

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6
Q

What mineral is needed to make thyroid?

A

Iodine

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7
Q

Where is TRH produced?

A

Hypothalamus

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8
Q

Where are the receptors for T3 and T4?

A

In the nuclei of cells

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9
Q

What is the action of thyroid hormones?

A
  • Increased BMR and heat production

Lipid metabolism - Lipolysis and beta oxidation
Carbohydrate metabolism - Stimulates insulin dependent entry of glucose into cells, increasing gluconeogenesis and glycogenolysis
Sympathomimetic - Increases response to catecholamines by increasing receptor number on target cells

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10
Q

What is the effect of thyroid hormone on the CVS?

A
  • Increases heart response to catecholamines

- Increases CO by increasing HR and force of contraction

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11
Q

What is the effect of thyroid hormone on peripheral vasculature?

A
  • Vasodilation to carry heat to body surface
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12
Q

What is the effect of thyroid hormone on the nervous system?

A
  • Myelination of nerves

- Development of neurones

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13
Q

What thyroid function tests should you ask for if you suspect hyperthyroidism?

A
  • T3 and T4

- TSH (all will have low TSH apart from TSH secreting pituitary adenoma)

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14
Q

What thyroid function tests should you ask for if you suspect hypothyroidism?

A
  • T4
  • TSH
    T3 will not add any extra information
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15
Q

What is sick euthyroidism?

A
  • TFT’s become deranged with systemic illness
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16
Q

What is TPOAbs? What is it testing?

A

TPOAbs - Thyroid peroxidase antibodies

  • Increased in hypothyroid autoimmune thyroid disease
  • If positive in Grave’s, there is an increased chance of developing hypothyroidism later on
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17
Q

What does TSH receptor antibody test for?

A
  • Grave’s disease, raised

- Useful in pregnancy

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18
Q

What does serum thyroglobulin test for?

A
  • Treatment of carcinoma

- Detection of self medicated hyperthyroidism if thyroglobulin is low

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19
Q

What is the use of ultrasound in thyroid disease?

A
  • Can distinguish between cystic benign nodules and solid malignant nodules
20
Q

When is a fine needle aspiration indicated?

A
  • A solitary nodule

- Multinodular goitre

21
Q

What is the use of an isotope scan?

A
  • Useful to determine the cause of hyperthyroidism
  • Finds retrosternal goitre
  • Finds ectopic thyroid tissue
  • Finds thyroid metastases with whole body CT
22
Q

What patients should you screen for thyroid abnormalities?

A
  • AF
  • Hyperlipidaemia (hypothyroidism)
  • Women with type I DM during 1st trimester and post delivery
  • Amiodarone or lithium (biannually)
  • Downs syndrome, Turners syndrome, Addisons disease (annually)
23
Q

What are the symptoms of hyperthyroidism?

A
  • Diarrhoea
  • Weight loss
  • Increased appetite (paradoxical weight gain in 10%)
  • Overactive
  • Sweats
  • Heat intolerance
  • Palpitations
  • Tremor
  • Irritability
  • Labile emotions
  • Oligomennorrhoea +/- infertility
24
Q

What are the signs of hyperthyroidism?

A
  • Pulse fast/irregular - AF/SVT
  • Warm moist skin
  • Fine tremor
  • Palmar erythema
  • Thin hair
  • Lid lag
  • Lid retraction
  • Goitre
  • Thyroid nodules
  • Thyroid bruit
25
Q

What are some specific signs of grave’s disease?

A

Eye disease - exopthalmous, ophthalmoplegia

Pretibial myxoedema - Oedematous swellings above lateral malleoli

Thyroid acropachy - Clubbing, painful finger and toe swelling, periosteal reaction in limb bones

26
Q

What investigations would you undertake in suspected hyperthyroidism?

A

You want to distinguish between thyrotoxicosis and actual hyperthyroidism

Bloods -

  • TSH, T3, T4
  • TSH receptor antibodies (TRAbs) diagnoses Grave’s

Isotope scanning -

  • If TRAbs are negative
  • Thyroiditis will have low uptake on thyroid scan, actual hyperthyroidism will have high uptake

Ultrasound -

  • Only if palpable nodule
  • From this, decide if to do FNA

Visual assessment -
- Visual acuity and visual fields

27
Q

What are the causes of hyperthyroidism?

A
  1. Grave’s disease
  2. Toxic multinodular goitre
  3. Toxic adenoma
  4. Ectopic thyroid tissue
  5. Exogenous - Iodine excess - contamination, contrast, levothyroxine
  6. Subacute de Quervain’s thyroiditis
  7. Amiodarone, lithium
  8. Postpartum
  9. TB
28
Q

What is the cause of Grave’s disease?

A
  • Circulating IgG autoantibodies binds to and activates GPCR of thyroglobulin
  • Causes smooth thyroid enlargement and increased hormone production (esp T3)
29
Q

What triggers Grave’s disease?

A
  • Stress
  • Infection
  • Childbirth
30
Q

What is Grave’s associated with?

A

Other autoimmune diseases

  • Vitiligo
  • Addison’s
  • Type 1 DM
31
Q

What is toxic multinodular goitre?
Where is it common?
When is surgery indicated?

A

Nodules secrete thyroid hormones.

  • Seen in the elderly and in iodine deficient areas
  • Surgery is indicated when there are compressive symptoms of the goitre (dysphagia, dyspnoea)
32
Q

What is toxic adenoma?

How can you differentiate this from malignancy?

A

A solitary nodule that produces T3 and T4.

On a radioisotope scan the nodule is ‘hot’ and the rest of the gland is suppressed.

33
Q

Where can ectopic thyroid tissue be found?

A
  • Metastatic follicular thyroid cancer

- Ovarian teratoma with thyroid tissue (struma ovarii)

34
Q

What is subacute de Quervain’s thyroiditis?
What would make you think this?
What is the treatment?

A
  • Self limiting post viral with a painful goitre
  • Increased temperature and raised ESR
  • Low isotope uptake on scan
  • Treat with NSAID’s, and symptomatic treatment with beta blockers
35
Q

What is the treatment for hyperthyroidism?

A
  1. Beta blockers - Controls symptoms
  2. Anti thyroid medication
    - Titration with carbimazole, reduce according to TFT’s every 1-2 months
    - Block and replace aka give carbimazole and levothyroxine simultaneously. Less risk of iatrogenic hypothyroidism.
    - Need FBC and LFT’s before they start
  3. Radioactive iodine - Most become hypothyroid post treatment. Cant be used in pregnancy/lactation.
  4. Thyroidectomy - Risk of recurrent laryngeal nerve damage (hoarse voice) and hypoparathyroidism. Thyroid replacement needed.
  5. Seek expert help in pregnancy and infancy.
36
Q

What are the side effects of carbimazole?

What should you warn a patient about?

A
  • Agranulocytosis (low neutrophils) so risk of dangerous sepsis
  • Stop if they get signs of infections and get a FBC urgently (eg fever, mouth ulcers, sore throat)
37
Q

What are the complications of hyperthyroidism?

A
  • Heart failure (toxic cardiomyopathy)
  • Angina
  • AF
  • Osteoporosis
  • Opthalmopathy
  • Gynaecomastia
  • Thyroid storm
38
Q

What are the symptoms of hypothyroidism?

A
  • Tiredness
  • Sleepy
  • Low mood
  • Cold disliking
  • Weight gain
  • Constipation
  • Menorrhagia
  • Hoarse voice
  • Memory loss and cognition impairment
  • Dementia
  • Myalgia
  • Cramps
  • Weakness
39
Q

What are the signs of hypothyroidism?

BRADYCARDIC

A 
B - Bradycardia
R - Reflexes relax slowly
A - Ataxia (cerebellar)
D - Dry thin hair/skin
Y - Yawning/drowsy/coma
C - Cold hands and low temperature
A - Ascites and non pitting peripheral oedema
R - Round puffy face/double chin/obese
D - Defeated demeanour
I - Immobile or ileus
C - CCF
40
Q

What are the blood results for hypothyroidism?

A
  • Raised TSH (over 4mu/L) (low in rare secondary hypothyroidism)
  • Low T4
  • Increased cholesterol and triglyceride
  • Macrocytic anaemia
41
Q

What are the causes of primary autoimmune hypothyroidism?

A
  • Primary atrophic hypothyroidism - diffuse lymphocytic infiltration of the thyroid leading to atrophy. No goitre.
  • Hashimoto’s thyroiditis - Goitre due to lymphocytes and plasma cell infiltration. Commoner in women 60-70.
42
Q

What are the non autoimmune causes of primary hypothyroidism?

A
  • Iodine deficiency
  • Post thyroidectomy/radioiodine treatment
  • Drug induced - antithyroid, amiodarone, lithium, iodine
  • Subacute thyroiditis - temporary after hyperthyroid phase
43
Q

What is the cause of secondary hypothyroidism?

A
  • Not enough TSH due to hypopituitarism (very rare)
44
Q

What is autoimmune hypothyroidism associated with?

A
  • Other autoimmune conditions
  • Turner’s and Downs syndrome
  • Primary biliary cholangitis
  • Cystic fibrosis
45
Q

What is the risks of pregnancy with hypothyroidism?

A
  • Eclampsia
  • Anaemia
  • Prematurity
  • Low birthweight
  • Stillbirth
  • PPH
46
Q

What is the treatment for hypothyroidism?

A

Healthy and young -

  • Levothyroxine - Ensure TSH is not suppressed
  • Check TSH every 2-3 months, then check TSH yearly once stabilised
  • Council that it may take 6 months for TSH to go back to normal

Elderly/IHD -
- Use lower dose as may precipitate angina or MI

47
Q

Why do problems occur with amiodarone?

How can it cause these problems?

What should you monitor?

A
  • It is structurally like iodine
  • Can cause hypo - toxicity from iodine excess, inhibiting T4
  • Can cause hyper - Destructive thyroiditis

Check TFT’s biannually and thyroidectomy if amiodarone cannot be stopped

Endocrinology (11 decks)

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