Thyroid Disorders

Question 1

Hyperthyroidism Symptoms:

Answer 1

• Heat intolerance, Weight loss, Diarrhoea, Tachycardia, Excitability, Tremors, Angina pain, Sweating, Arrythmias

Question 2

Hyperthyroidism lab test results

Answer 2

High T4 + T3, Low TSH

Question 3

Thyroid hormones regulate:

Answer 3

Metabolic rate, Heart rate, digestive function, muscle control, brain development

Question 4

Antithyroid drugs for hyperthyroidism

Answer 4

 Antithyroid drugs are used to treat hyperthyroidism… Carbimazole is the most commonly used drug. Alternatively, Propylthiouracil can be used if patients are intolerant or for those who experience sensitivity reactions to Carbimazole.
 Overuse of thyroid drugs can lead to hypothyroidism, an alternative regimen including a combination of Carbimazole with Levothyroxine may be used in a blocking-replacement regimen, therapy is usually given for 18 months. However, this regimen is not suitable during pregnancy.
 Radioactive Sodium Iodide solution is used increasingly for the treatment of thyrotoxicosis at all stages, in patients with cardiac disease, and in patients who relapse after thyroidectomy.
 Propranolol is used for rapid relief of thyrotoxic symptoms and can be used in conjunction with the drugs above.
 Rashes + itching are a common s.e. of antithyroid drugs – continue treatment and consider antihistamine

Question 5

Antithyroid drugs in pregnancy

Answer 5

• Radioactive iodine is contraindicated in pregnancy.
• Propylthiouracil and Carbimazole can be given, but the blocking-replacement regimen is not suitable.
• Carbimazole is associated with congenital defects (asplasia cutis of neonate) therefore propylthiouracil is given in first trimester of pregnancy.
• In second trimester, switch to carbimazole due to the potential risk of hepatotoxicity with propylthiouracil.
• Both propylthiouracil and carbimazole cross the placenta hence the lowest dose that will control the hyperthyroid state should be used (to avoid fetal goitre and hypothyroidism).

Question 6

Carbimazole and SE

Answer 6

Carbimazole is 1st Line in hyperthyroidism

• Side effects:
o Bone marrow suppression: (Neutropenia + Agranulocytosis) Patients should report signs of sore throat, bruising, mouth ulcers, fever, malaise and infection. WBC count should be carried out if there is suspected infection.
o Rashes/itching: antihistamine or switch to propylthiouracil
o Risk of acute pancreatitis
• Women of child bearing potential should use effective contraception

Question 7

Prophylthiouracil

• Side effects:

Answer 7

o Hepatoxicity. Stop + report signs of liver failure, anorexia, fatigue, jaundice, nausea, vomiting, abdominal pain, pale stools, malaise, pruritus, dark urine, raised liver enzymes

Question 8

Thyrotoxic crisis

Answer 8

• Emergency treatment required with IV administration of fluids, propanolol and hydrocortisone as well as oral iodine solution and carbimazole or propylthiouracil which may need to be administered by nasogastric tube
• Symptoms of thyrotoxicosis  increased HR (>140) + PR, tachycardia (arrythmias), heat intolerance, diarrhoea, seizures

Question 9

Thyroidectomy

Answer 9

o Give Iodine 10-14 days before partial thyroidectomy (Adjunct to anti-thyroid drugs but not long term)

Question 10

Hypothyroidism Symptoms:

Answer 10

• Cold intolerance, Weight gain, Constipation, Bradycardia, Lethargy, Muscle cramps, Slow movements, Slow thoughts, Depression, Hair thinning

Question 11

Hypothyroidism lab test results

Answer 11

Low T4 + T3, High TSH

Question 12

treat hypothyroidism

Answer 12

• Thyroid hormones are used to treat hypothyroidism (myxoedema). Levothyroxine sodium is the treatment of choice for maintenance therapy.
• Liothyronine sodium is used in severe hypothyroid states where a rapid response is required. It has a similar action to levothyroxine, but it is more rapidly metabolised and has a more rapid effect.
• Liothyronine sodium IV is used in hypothyroid coma. Adjunct therapy includes IV fluids, hydrocortisone

Question 13

• The side effects of thyroid hormones are

Answer 13

are similar to hyperthyroidism i.e. diarrhoea, arrhythmias, palpitations, tachycardia, sweating, fever and weight loss.

Question 14

Thyroid hormones and anticoagulants

Answer 14

• Thyroid hormones can enhance the anticoagulant effect of warfarin.

Question 15

Levothyroxine - cautions and SE

Answer 15

Levothyroxine is 1st line for hypothyroidism

• Cautions: Baseline ECG is needed because changes induced by hypothyroidism can be confused with ischaemia
• Side effects: initial dosage in patients with cardiovascular disorders – if metabolism occurs too rapidly (causing diarrhoea, nervousness, insomnia, tremors, rapid pulse etc.) reduce dose or withhold for 1-2 days and start again at a lower dose.
• Take in the morning at least 30 mins before breakfast, caffeine containing liquids or other medication

Question 16

Liothyronine - cautions and SE

Answer 16

• Cautions: Baseline ECG is needed because changes induced by hypothyroidism can be confused with ischaemia
• Side effects: initial dosage in patients with cardiovascular disorders – if metabolism occurs too rapidly (causing diarrhoea, nervousness, insomnia, tremors, rapid pulse etc.) reduce dose or withhold for 1-2 days and start again at a lower dose.
• Prescribing and dispensing information: patients switched to a different brand should be monitored as brands without a UK license may not be bioequivalent. If liothyronine is continued long-term, TFTs should be repeated 1-2 months after any change in brand.

Question 17

Hypothyroidism Causes:

Answer 17

Hashimoto’s diease (autoimmune- destroys thyroid gland), inflammation of thyroid (Toxic goiter), tumour, iodine-deficiency, medication (Amiodarone, lithium, dopamine agonists, glucocorticosteriods, somatostatin)

Question 18

Hyperthyroidism Causes:

Answer 18

Grave’s disease (autoimmune-enlarges thyroid gland), inflammation of thyroid (goitre), tumour, medication (Amiodarone)