Thyroid hormone disorders

Question 1

What is a goitre?

Answer 1

Painful diffuse swelling in the neck, tells you there is something wrong with the thyroid, but not if it is over or under acting

Question 2

What are the causes of adult hypothyroidism?

Answer 2

Most coomon cause is Hashimoto’s thyroiditis- autoimmune destruction of gland by antibodies to thyroglobulin and peroxidase enzymes- low levels of thyroid hormones
Slow to develop, familial, most common in middle aged women

Question 3

What are the characteristics of adult hypothyroidism?

Answer 3

Serum antibodies
White blood cell infiltration of gland
Goitre

Question 4

What is primary hypothyroidism?

Answer 4

A functional deficit in the thyroid gland

Question 5

What are the symptoms of adult hypothyroidism?

Answer 5

Low BMR- slow bodily functions, movement, reflexes and muscle cramps
Weight gain, cold intolerance, decreased sweating, constipation, heavy periods, deep voice
Thickened, coarse, dry and puffy skin, hair loss
Tiredness/lethargy, depression, slow speech, bradycardia
Increased plasma carotene- yellow tinge to skin
Serum T3/T4 levels low, TSH levels high= no feedback

Question 6

What are the diagnostic tests for adult hypothyroidism?

Answer 6

Use immunoradiometric assay= measure total and free T3 and T4 by RIA and TSH
Use TRH test- distinguish between pituitary and thyroid dysfunction
Use TSH test- distinguish between primary hypothyroidism and other conditions

Question 7

What is the treatment for adult hypothyroidism?

Answer 7

Thyroid hormone replacement therapy for life
Levothyroxine sodium- dose gradually increased to find maintenance dose
Liothyronine sodium- for severe hypothyroidism
Serum TSH and T4 measured to check dosing regimen

Question 8

What are the causes of childhood hypothyroidism?

Answer 8

Ectopic location/abnormal development of thyroid gland

Cretinism

Question 9

What are the symptoms of childhood hypothyroidism?

Answer 9

Congenital hypothyroidism- neonates dwarfed, protruding tongue and abdomen, retardation, coarse hair, dry yellow skin
Juvenile hypothyroidism- stunted growth, delayed sexual development, mental slowness

Question 10

What is the diagnosis of childhood hypothyroidism?

Answer 10

TSH assay of heel-prick blood

Question 11

What is the treatment for childhood hypothyroidism?

Answer 11

Thyroid hormone replacement therapy for life

Serum TSH and T4 measured to check dosing regimen

Question 12

What are the other causes of hypothyroidism?

Answer 12

Surgical removal/radioactive iodine treatment
Iodine deficiency- low dietary intake of iodine
Amiodarone administration- anti-arrhythmic drug containing iodine, interferes with T4 to T3 conversion, contraindicated in those with thyroid dysfunction/iodine sensitivity, drug withdrawal

Question 13

What is the cause of secondary hypothyroidism?

Answer 13

Inadequate TSH production, hypothalamic or pituitary disease
Deficiencies in other pituitary trophic hormones
Treated with replacement glucocorticoids, sex hormones and thyroid hormones

Question 14

What are the causes of hyperthyroidism (Graves disease)?

Answer 14

Autoimmune disease characterised by thyroid stimulating immunoglobulins, bind to TSH receptors on follicle cells, increase thyroid hormone production- body cannot switch it off
Most common in women, associated with myasthenia gravis, addison’s disease and pernicious anaemia

Question 15

What are the symptoms of hyperthyroidism?

Answer 15

High BMR- increased heat, excess sweat, fast metabolism
Weight loss due to muscle wasting, diarrhoea and light periods
Rapid pulse, palpitations and hypertension
Restlessness, over-anxiety, nervousness, irritability, emotional instability
Eye changes- eyelid retraction, eyeball protrusion, thickening of extraocular muscles
Goitre
Serum T3/T4 levels high, TSH levels low- excessive feedback

Question 16

What are the diagnostic tests for hyperthyroidism?

Answer 16

Measure total and free T3 and T4 by RIA and TSH by immunoradiometric assay
TRH test used, expected rise in TSH not seen with hyperthyroidism

Question 17

What is the treatment for hyperthyroidism?

Answer 17

Carbimazole (first line) or propylthiouracil, used for long term treatment and before use of radioactive iodine/surgery
Dose gradually reduced, then withdrawn- usually treat fro 12-18 months
Blocking replacement regimen- higher doses of carbimazole and levothyroxine for 18 months, not in preganancy

Question 18

What are the side effects of the treatment for hyperthyroidism?

Answer 18

Skin rash, fever, headache, nausea, arthropathy

Question 19

What is the treatment for hyperthyroidism in pregnancy?

Answer 19

Lowest possible dose, propylthiouracil for first trimester, then switch to carbimazole

Question 20

How is aqueous iodine solution used to treat hyperthyroidism?

Answer 20

Use prior to surgery for 10-14 days, to reduce size and vascularity of gland
Excess iodine inhibits thyroid hormone production
Only works for a few weeks
Propranolol and nadolol used initially to relieve symptoms quickly in conjunction with anti-thyroid drugs and radioactive iodine, reduce symptoms

Question 21

How is surgery used to treat hyperthyroidism?

Answer 21

Thyroidectomy effective in patients with recurrent hyperthyroidism, large goitre
Patients controlled in euthyroid state before surgery with carbimazole
Must control cardiovascular symptoms before operating
Will get hypothyroidism later depending on extent of gland removal

Question 22

How is radioactive iodine used?

Answer 22

For all ages, cardiac diseases, problems with other therapies/compliance, relapse after surgery and elderly
Contraindicated in pregnancy
Accumulates in thyroid and destroys overactive tissue by local irritation over 1-6 months
Treat symptoms with propranolol or carbimazole
Patients must be controlled in euthyroid state before treatment
Most/all of gland destroyed- life long therapy replacement, monitor TSH levels

Question 23

What are the other causes of hyperthyroidism?

Answer 23

Toxic multinodular goitre- common in elderly, mild hyperthyroidism, no exopthalmos, treat with surgery or radioactive iodine
Solitary toxic nodule- all ages, benign adenoma, mild hyperthyroidism, treat with surgery or radioactive iodine
Subacute thyroiditis- rare, self limiting inflammation of thyroid following upper respiratory tract infection, treat with analgesicsm corticosteroids and propranolol

Question 24

What is thyrotoxic crisis?

Answer 24

Rare, serious emergency due to release of high levels of thyroid hormones after infection/stress in controlled patients, or after surgery in non-euthyroids
Side effects- extreme restlessness, confusion, abdominal pain, tachycardia

Question 25

What is the treatment for thyrotoxic crisis?

Answer 25

Treat with propranolol, carbimazole/propylthiouracil, Lugol’s solution, hydrocortisone and IV fluids

Question 26

What are the characteristics of secondary hyperthyroidism?

Answer 26

Secret ingestion of thyroid hormone for weight loss
Rare- TSH producing pituitary adenoma
Ovarian teratoma with thyroid elements
Metastatic thyroid carcinoma involving follicles
Treat with amiodarone

Question 27

What is sick euthyroid syndrome?

Answer 27

Abnormal thyroid function tests- in patients suffering from illnesses not related to hypo/hyperthyroidism
MI, renal fail, cirrhosis, burns, sepsis, surgical trauma, anorexia, malnutrition
Low T3 and T4, high rT3 but normal TSH diagnostic
Not hyperthyroidism, treat underlying condition