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Y3 Medicine: Diabetes and Endocrinology > Hyperthyroidism > Flashcards

Hyperthyroidism Flashcards

1
Q

What is hyperthyroidism?

A

A biochemical diagnosis which occurs when there is pathologically increased thyroid hormone production and secretion by the thyroid gland.

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2
Q

What is thyrotoxicosis?

A

Thyrotoxicosis is the clinical manifestation of excess circulating thyroid hormones due to any cause, including hyperthyroidism.

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3
Q

What is primary hyperthyroidism?

A

Primary hyperthyroidism occurs when thyrotoxicosis is caused by an abnormality of the thyroid gland such as Graves’ disease.

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4
Q

What risk factors are associated with hyperthyroidism?

A
  • Female
  • Family history
  • Smoking
  • Low iodine intake
  • Autoimmune disease
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5
Q

What are the causes of thyrotoxicosis with hyperthyroidism (increased thyroid hormone synthesis)?

A
  • Grave’s disease
  • Toxic multinodular goitre
  • Toxic thyroid nodule (adenoma)
  • High concentrations of human chorionic gonadotrophin (hCG)
  • Iodine
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6
Q

What are the causes of thyrotoxicosis without hyperthyroidism (increased availability of preformed thyroid hormone)?

A
  • Thyroiditis
  • Exogenous thyroid hormone
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7
Q

What is Grave’s disease?

A

This is the most common cause of hyperthyroidism in iodine-sufficient areas, accounting for about 80% of cases. It is a systemic autoimmune disorder mediated by thyroid-stimulating hormone (TSH)-receptor antibodies (TRAbs) that stimulate the TSH receptor, leading to thyroid hyperplasia and unregulated excessive production and secretion of thyroid hormone.

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8
Q

What are the signs of hyperthyroidism?

A
  • Agitation, fine tremor, warm moist skin and palmar erythema
  • Sinus tachycardia, atrial fibrillation, heart failure and peripheral oedema
  • Thyroid enlargement (a goitre)
  • Pruritus, urticaria, vitiligo and diffuse alopecia
  • Muscle wasting, proximal myopathy and hyper-reflexia
  • Gynaecomastia in men
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9
Q

What are the symptoms of hyperthyroidism?

A
  • Rapid-onset malaise, fever and thyroid pain
  • Compression symptoms of breathlessness, hoarse voice and dysphagia
  • Agitation, emotional lability, insomnia, irritability, anxiety and palpitations
  • Exercise intolerance, fatigue and muscle weakness
  • Heat intolerance and increased sweating
  • Increased appetite with unintentional weight loss and diarrhoea
  • Subfertility, oligomenorrhoea and amenorrhoea
  • Polyuria, thirst and generalized itch
  • Reduced libido and gynaecomastia in men
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10
Q

What investigations should be ordered for hyperthyroidism?

A
  • TSH
  • Serum free or total T3
  • Serum free or toral T4
  • Calculation of T3/T4 or T3/T4 ratio
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11
Q

Why investigate TSH? And what may this show?

A
  • Initial screening test
  • TSH level is below the normal reference range
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12
Q

Why investigate serum free or total T3? And what may this show?

A
  • If the TSH level is below the normal reference range, the free thyroxine (FT4) and free triiodothyronine (FT3) levels should be measured in the same sample
  • T3 levels are raised above the normal reference ranges
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13
Q

Why investigate serum free or total T4? And what may this show?

A
  • If the TSH level is below the normal reference range, the free thyroxine (FT4) and free triiodothyronine (FT3) levels should be measured in the same sample
  • T4 levels are raised above the normal reference ranges
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14
Q

What test needs to be done if Grave’s diease is suspected?

A

TSH-receptor antibodies (TRAbs)

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15
Q

When is a thyroid ultrasound used in investigating hyperthyroidism?

A

Arrange an ultrasound of the neck to image palpable thyroid enlargement or focal nodularity.

Highly sensitive for detection of thyroid nodules.

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16
Q

What are the treatment options for hyperthyroidism?

A
  • Antithyroid drugs
  • Radioactive iodine treatment
  • Thyroid surgery
17
Q

Briefly describe the use of antithyroid drugs

A

Antithyroid drug treatments (carbimazole and propylthiouracil) are used to decrease thyroid hormone synthesis, by acting as a preferred substrate for iodination by thyroid peroxidase, the key enzyme in thyroid hormone production.

Antithyroid drugs should only be initiated on specialist advice, and are typically used:

  • Short-term to restore euthyroidism in preparation for definitive treatment with radioactive iodine treatment or thyroid surgery
  • Medium-term with the aim of inducing remission of Graves’ disease
  • Long-term if radioactive iodine treatment or surgery is contraindicated or declined
18
Q

Give examples of drugs used in antithyroid treatment

A

Carbimazole and propylthiouracil

19
Q

Briefy describe the use of radioactive iodine treatment

A

Radioactive iodine treatment induces damage of DNA leading to death of thyroid cells, causing a decrease in thyroid function and/or reduction in thyroid size.

It is a first-line definitive treatment for adults with Graves’ disease and those with toxic multinodular goitre.

20
Q

Briefly describe the use of thyroid surgery

A

Options include total thyroidectomy, or hemithyroidectomy for a single thyroid nodule, in people:

  • To prevent the recurrence of hyperthyroidism
  • With compression symptoms from a large toxic multinodular goitre
  • With a co-existing potentially malignant thyroid nodule
  • Who have not tolerated antithyroid drug treatment or it is ineffective, especially in pregnancy or active Graves’ orbitopathy, or if radioactive iodine treatment is unsuitable
21
Q

What are the complications of hyperthyroidism?

A
  • Graves orbitopathy
  • Thyrotoxic crisis (thyroid storm)
  • Atrial fibrillation
  • Heart failure
  • Osteoporosis
22
Q

What can trigger a thyrotoxic crisis?

A

May occur after a trigger such as acute infection, trauma, pregnancy, surgery including thyroidectomy or stroke.

It may occur in people with previously undiagnosed hyperthyroidism or those who have abruptly stopped antithyroid medication.

23
Q

What are the clinical features of thyrotoxic crisis?

A

linical features reflect systemic decompensation and include fever, tachycardia, agitation, hyperthermia, hypertension, atrial fibrillation, heart failure, jaundice, delirium and coma.

The mortality rate is estimated at about 10% due to hyperthermia, cardiac arrhythmias, multi-organ failure and sepsis.

Y3 Medicine: Diabetes and Endocrinology (24 decks)

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