Hyperthyroidism + Graves

Question 1

Definition of hyperthyroidism

Answer 1

common endocrine condition caused by an overactive thyroid gland causing an excess of thyroid hormone and thyroxtoxicosis

Question 2

What is thyrotoxicosis

Answer 2

refers to an excess of thyroid hormone, having an overactive thyroid gland is not a prerequisite (e.g.consumption of thyroid hormone).

Question 3

Epidemiology of hyperthyroidism

Answer 3

• The overall prevalence of hyperthyroidism is approximately 1.3% and increases to 4-5% in older women
• Affects 2-5% of all women at some time
• Mainly between 20-40yrs

Question 4

Aetiology of hyperthyroidism

Answer 4

Primary:
Graves
Toxic multinodular goitre
Toxic adenoma
Subclinical hyperthyroidism
Thyroiditis

Secondary:
Pituitary adenoma
ectopic tumour
hypothalamic tumour

Question 5

RF Hyperthyroidism

Answer 5

• Family history
• Auto-immune disease e.g. vitiligo, type 1 diabetes, Addison’s disease

Question 6

Primary hyperthyroidism pathophysiology

Answer 6

involves an excessive production of T3/T4 by the thyroid gland due to pathology affecting the thyroid gland itself.
Increased metabolic rate and sympathetic NS activation
More common subtype

Question 7

Secondary hyperthyroidism

Answer 7

occurs due to excessive stimulation of the thyroid gland by TSH, secondary to pituitary or hypothalamic pathology, or from an ectopic source such as a TSH-secreting tumour.

Rarer

Question 8

Key presentation pneumonic

Answer 8

THYROIDISM

Question 9

Thyroidism pneumonic for key presentation

Answer 9

tremor, heart rate increase, yawning, restless, oligomenorrhoea, irritability, diarrhoea, intolerance to heat, sweating, muscle wasting (weight loss).

Question 10

Signs of Hyperthyroidism

Answer 10

• Postural Tremor
• Palmar erythema
• Hyperreflexia
• Sinus tachycardia/ arrhythmia
• Goitre
• Lid lag and retraction

Question 11

Symptoms of hyperthyroidism

Answer 11

• Weight loss
• Anxiety
• Fatigue
• Reduced libido
• Heat intolerance
• Palpitations
• Menstrual irregularity

Question 12

1st line investigation for Hyperthyroidism

Answer 12

Thyroid function tests
Graves : Low TSH High T4
Subclinical hyperthyroidism: Low TSH normal T4
Secondary hyperthyroidism: High TSH High T4

Question 13

Other investigations for hyperthyroidism

Answer 13

Antibodies;
Anti TSH receptors 95% common in graves
Anti TPO
Anti thyroglobulin

Question 14

1st line therapy for hyperthyroidism

Answer 14

• Beta blocker e.g. propranolol for symptomatic relief
• Anti-thyroid medication: preferred in mild disease - 1st line is carbimazole

Question 15

Radiodine treatment

Answer 15

first line treatment in more than mild Graves’ or toxic multinodular goitre

Contraindicated inpregnancy, age < 16 years old, when breastfeeding or those with established eye disease as can make eye symptoms worse

Question 16

Complications of management

Answer 16

• Surgery complications - risk of hypothyroidism, hypoparathyroidism, and recurrent laryngeal nerve palsy resulting in a hoarse voice, trachael compression from post-operative bleeding
• Anti-thyroid drugs - agranulocytosis and neutropenia or hepatotoxicity

Question 17

Complications

Answer 17

• Cardiovascular: heart failure, atrial fibrillation
• Musculoskeletal:osteoporosis, proximal myopathy
• Thyrotoxic crisis/ thyroid storm

Question 18

What is Thyrotoxic crisis/ thyroid storm

Answer 18

• Rapid T4 increase. Medical emergency!
  
  • Features include hyperpyrexia, tachycardia, extreme restlessness
    and eventually delirium, coma and death
  • Treated with large doses of carbimazole, propranolol, potassium iodide, IV hydrocortisone to stop conversion of T4 to T3

Question 19

Iatrogenic complications due to treatment

Answer 19

• Agranulocytosis and neutropaenic sepsis: secondary to carbimazole
• Hepatotoxicity: secondary to propylthiouracil
• Congenital malformations: carbimazole in first trimester
• Foetal goitre and hypothyroidism: any antithyroid medication in pregnancy at high doses

Question 20

Graves disease definition

Answer 20

Graves’ disease is the most common cause of hyperthyroidism worldwide. It is an autoimmune induced excess production of thyroid hormone

Question 21

Epidemiology of Graves disease

Answer 21

• This is the MOST COMMON CAUSE of hyperthyroidism (2/3rds of cases)
• More common in FEMALES than males
• Typically presents at 40-60yrs (appears earlier if maternal family history)

Question 22

Aetiology of Graves

Answer 22

• Serum IgG antibodies, specific for Graves’ disease, known as TSH receptor stimulating antibodies (TSHR-Ab) bind to TSH receptors in the thyroid
• Thereby stimulating thyroid hormone production (T3 & T4) - essentially they behave like TSH
• Resulting in excess secretion of thyroid hormones and hyperplasia of thyroid follicular cells resulting in hyperthyroidism and diffuse goitre
• Persistent high levels predict a relapse
  when drug treatment is stopped
• Similar auto antigen can also result in retro-orbital inflammation - graves opthalmopathy

Question 23

RF 4 Graves

Answer 23

• Family history
• Female
• Autoimmune disease
• Stress
• High iodine intake
• Radiation
• Tobacco use

Question 24

Pathophysiology of Graves

Answer 24

Involves anti-TSH antibodies causing increased thyroid hormone production through stimulation of the TSH receptor.

Of note, anti-TSH antibodies react with orbital antigens in fat and connective tissue, causing retro-orbital inflammation which leads to thyroid eye disease.

Question 25

S + S of Graves

Answer 25

- Thyroid acropachy - clubbing, swollen fingers and periosteal bone formation - Thyroid bruit - continuous sound heard over thyroid mass - Pretibial myxoedema - raised, purple-red symmetrical skin lesions over the anterolateral aspects of the shin - Eye signs - Exophthalmos - protruding eye - Ophthalmoplegia - paralysis or weakness of eye muscles

Question 26

1st line investigation for Graves Disease

Answer 26

TFT's: raised T3 and T4, reduced TSH. All other aspects of investigation and management are the same as generic hyperthyroidism