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2a > Thyroid disorders > Flashcards

Thyroid disorders Flashcards

Hyper- and hypo-thyroidism, Graves' and Hashimoto's thyroiditis. 17/4/18, 18/4/18 List band 1 condition based on lecture 17/4/18 and OHCM.

1
Q

What is thyrotoxicosis?

A

Excess thyroid hormones in the blood from any cause, such as hyperthyroidism, where the thyroid produces too much thyroid hormone.
(lecture 17.4.18)

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2
Q

By which mechanisms can thyrotoxicosis occur?

A
  1. Overproduction of thyroid hormone
  2. Leakage of preformed hormone from thyroid
  3. Ingestion of excess thyroid hormone.
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3
Q

What are the 3 most common causes of thyrotoxicosis?

A

Graves’ disease (80%)
Toxic multinodular goitre
Toxic adenoma (one nodule)

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4
Q

Give 3 main signs of Graves’ thyrotoxicosis

A

Tachycardia
Goitre
Bulging eyes
Others: tremor, palmar erythema

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5
Q

Describe the pathophysiology of Graves’ disease.

A

The body produced antibodies to the receptor for TSH which causes it to be chronically stimulated. The TSHr is expressed on the follicular cells of the thyroid gland so excess T3 and T4 is produced.
(wikipedia)

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6
Q

How does Graves’ disease cause infiltrative exophthalmopathy?

A

The thyroid gland and extraocular muscles may share a common antigen which binds to the autoimmune antibody, causing swelling behind the eyeball. The optic nerve gets straightened out and eyeballs are bulging and red.

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7
Q

How does thyrotoxicosis cause tachycardia?

A

Thyroxine (T4) increases resting heart rate and left ventricular contractility. T3 increases systemic vascular resistance via arteriolar smooth muscle cells.
(GPonline)

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8
Q

Give 3 symptoms of thyrotoxicosis.

A 
Heat intolerance
Weight loss
Sweating
Tremor
Increased appetite
Diarrhoea
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9
Q

What investigations would you do for suspected thyrotoxicosis?

A

Thyroid function tests: increased free T3 and T4, TSH low (primary)/ high (secondary)
Bloods: increased ESR, Ca, LFTs
History and exam usually sufficient
Thyroid auto-antibodies: TPO, Tg
Diagnose underlying cause using isotope scan to detect nodular disease or subacute thyroiditis.
Visual field tests

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10
Q

Describe the management of thyrotoxicosis

A
  1. Drugs:
    - symptom control: b-blocker eg propanolol
    - anti-thyroid: carbimazole, thyroxine
  2. Radioiodine
  3. Thyroidectomy
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11
Q

How does radioiodine work and what are the side-effects?

A

Restricts/destroys the function of the thyroid gland. Only works on the thyroid and salivary glands. Causes hypothyroidism, increases risk of thyroid storm in active hyperthyroidism.

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12
Q

Give 3 complications of thyrotoxicosis.

A

Heart failure, angina, AF, osteoporosis.

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13
Q

What is thyrotoxic storm?

A

Severe hyperthyroidism with agitation, confusion, coma, AF and heart failure. Emergency condition.

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14
Q

What is hypothyroidism?

A

Disorder in which the thyroid gland is underactive so does not produce enough thyroid hormone.

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15
Q

What is myxoedema?

A

Term used to describe swelling of the skin and underlying tissues giving a waxy consistency which occurs in hypothyroidism. Sometimes used to mean severe hypothyroidism.

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16
Q

Why is it important to have a low threshold for measuring TSH and TFTs?

A

Onset of hypothyroidism is insidious with non-specific symptoms so easily missed until late. If left untreated prognosis is bad -heart disease, dementia and mortality occur.
(OHCM)

17
Q

What are the risk factors for hypothyroidism?

A

Female (6:1 male)

>40 years old

18
Q

What are the symptoms of hypothyroidism?

A 
Weight gain due to oedema
Fatigue
Constipation
Dry, rough skin
Cold intolerance
19
Q

Describe the pathophysiology of primary atrophic hypothyroidism.

A

Primary atrophic hypothyroidism: autoimmune, common cause in females, where diffuse lymphocytic infiltration of the thyroid gland leads to atrophy (no goitre).

20
Q

What investigations would you do for suspected hypothyroidism and what would they show?

A

TFTs:
TSH - increased
Monitor T4 - decreased

21
Q

What causes hypothyroidism?

A

99% primary.
Autoimmune: Primary atrophic hypothyroidism, Hashimoto’s thyroiditis
Radioiodine therapy
Iodine deficiency (worldwide main cause)

22
Q

Describe the pathophysiology of Hashimoto’s thyroiditis

A

Hashimoto’s thyroiditis: autoimmune. lymphocytic and plasma cell infiltration lead to a goitre. Older women. Auto-antibody titres are high.

23
Q

Give 3 signs of hypothyroidism

A 
Bradycardia
Reflexes relax slowly
Ataxia
Dry, thin hair and skin
Yawning (drowsy)
Cold hands
Ascites
Round face/ obese
Defeated demeanor
Immobile
CCF (HF)
24
Q

Describe the management of hypothyroidism.

A 
Synthetic Levothyroxine (l-thyroxine) to normalise TSH.
If IHD, lower dose
(lecture)
25
Q

What is the half-life of l-thyroxine and why is this significant?

A

7 days, so wait before checking TSH to see if a dose change is right.

26
Q

Describe the epidemiology of thyroid cancers including the 3 main types.

A 
Rare - less than 1% of UK cancer.
60% papillary - younger patients
25% follicular - middle-age
5% medullary
(lecture, OHCM)
27
Q

What are the symptoms of thyroid cancer?

A

Lump in thyroid region of neck
Hoarse voice due to recurrent laryngeal nerve involvement
Anterior neck pain

28
Q

Give 3 signs of thyroid cancer

A

Lump in thyroid region of neck
Enlarged lymph node
Hoarse voice due to recurrent laryngeal nerve involvement
Usually patient is euthyroid at presentation (normal thyroid hormone levels)

29
Q

Why is thyroid cancer important to rule out in young people with lumps in the thyroid?

A

Nodules are unlikely in under 20s so potential for

malignancy is greater (wikipedia)

30
Q

Give a risk factor for thyroid cancer.

A

Ionising radiation eg lymphoma treatments
Thyroid diseases eg thyroiditis (eg due to iodine deficiency)
MEN2 gene

31
Q

What investigations would you do if there is a lump in the patient’s thyroid?

A

T3, T4, TSH
Thyroid autoantibodies (AI hypo/hyperthyroid)
CXR - tracheal goitres and metastases?
Radionuclide scan - hot (hyperfunctioning) or cold (hypofunctioning) lesion.
(OHCM)

32
Q

Describe the treatment for papillary thyroid cancer.

A
  1. Total thyroidectomy to remove non-obvious tumour.
  2. +/- radioiodine/node excision to ablate residual cells
  3. Thyroxine to suppress TSH
33
Q

What affects prognosis of thyroid cancer?

A

Papillary: Slow-growing, localised, good prognosis if young and female.
Follicular: spreads early, well-differentiated, so worse prognosis.

34
Q

Describe the treatment for follicular thyroid cancer.

A

More aggressive than papillary so all of the following

  1. Total thyroidectomy
  2. thyroxine
  3. radioiodine ablation.

2a (75 decks)

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