Thyroid

Question 1

Normal physiology

Answer 1

(Hypothalamus) Thyrotropin releasing hormone.
(Pituitary) Thyroid stimulating hormone.
(Thyroid) T3 + T4. T3 is the active form, but 90% is T4.
Works to increase metabolism, growth hormone, HR etc.

Question 2

Hypothyroidism- symptoms

Answer 2

Weight gain, constipation, cold intolerance, lethargy, menorrhagia, dry skin, non-pitting oedema to hands and face, coarse hair, loose lateral 1/3 of eyebrows. Decreased deep tendon reflexes.

Question 3

Hyperthyroidism- symptoms

Answer 3

Weight loss, diarrhoea, heat intolerance, manic restlessness, palpitations, sweating, oligomenorrhoea, anxiety, tremor.

Question 4

Expected TFT for: Thyrotoxicosis/Grave’s disease

Answer 4

TSH- low
Free T4- high
Grave’s disease- TSH-Ab present

Question 5

Expected TFT for: Primary hypothyroidism/Hashimoto’s

Answer 5

TSH- high
Free T4- low
Hashimoto’s- Anti TPO Ab present

Question 6

Expected TFT for: Secondary hypothyroidism

Answer 6

TSH- low
Free T4- low

Sick Euthyroid syndrome- low TSH and T4 seen in hospital patients. Reversed upon recovery from systemic illness. No treatment required.

Question 7

Expected TFT for: Sick Euthyroid syndrome

Answer 7

Low TSH
Low freeT4
Seen in hospital patients. Reversed upon recovery from systemic illness. No treatment required.

Question 8

Expected TFT for: Subclinical hypothyroidism

Answer 8

TSH- high
Free T4- normal
On the way to being hypothyroid but high levels of TSH are still maintaining a normal T4 for now.

Question 9

Hashimoto’s thyroiditis

Answer 9

Autoimmune condition. 10 x more common in women.
See Anti TPO antibodies in the blood.
Causes primary hypothyroidism.
Can be goitrous or atrophic. Firm, painless goitre.

Question 10

Causes of primary hypothyroidism

Answer 10

Hashimoto's 
Iodine deficiency
Post partum thyroiditis
Amiodarone induced
Lithium
Riedel's hypothyroidism- dense fibrous tissue replaces thyroid gland, hard thick painless goitre

Congenital hypothyroidism (screened for in heel prick test). Must treat within 4 weeks. Features: prolonged neonatal jaundice, delayed milestones, short, hypotonia, puffy face.

Question 11

Causes of secondary hypothyroidism

Answer 11

Pituitary adenoma
Down’s syndrome
Turner’s syndrome
Coeliac disease

Question 12

Hypothyroidism treatment

Answer 12

Levothyroxine and check TFTs 8-12 weeks later.
Lower dose if elderly or ischemic heart disease.
If pregnant increase dose by 25-50mcg

Question 13

De Quervain’s thyroiditis

Answer 13

Viral self limiting illness. Painful goitre due to inflammation.
Thyrotoxicosis -> hypothyroidism -> resolution

Question 14

Causes of hyperthyroidism

Answer 14

Grave's disease (IgG Ab to TSH receptors causes over stimulation of thyroid)
Toxic multinodular goitre
Solitary toxic adenoma
Thyroid cancer
Amiodarone induced
Pituitary adenoma

Question 15

Treatment for hyperthyroidism

Answer 15

Thioamides- carbimazole, propylthiouracil.
Radioactive iodine.
Beta blockers and calcium channel blockers to control adrenergic symptoms.

Question 16

Post partum thyroiditis

Answer 16

Thyrotoxicosis -> hypothyroidism -> resolution
TPO antibodies present in 90%
Propranolol for symptoms control. Levothyroxine for hypo phase.

Question 17

Thyrotoxicosis

Answer 17

Thyroid storm seen after surgery, infection, trauma, contrast CT due to iodine.
High temperature, tachycardia, hypertension, agitation, nausea and vomiting, abnormal LFTs +/- jaundice
Treat with beta blocker propranolol, paracetamol, anti-thyroid e.g. methimazole, dexamethasone.