Hypothyroidism

Question 1

What is hypothyroidism + what is it’s severest form

Answer 1

• Abnormally low activity of thyroid gland

- Severest form = MYXOEDEMA

Question 2

Who is affected

Answer 2

F»M

- Overt form = 2% women + 0.2% men

Question 3

What are the primary causes

Answer 3

• Autoimmune – Hashimoto’s thyroiditis (ass with goitre) + atrophic thyroiditis
• Iatrogenic – radio-iodine treatment, surgery, radiotherapy to neck (e.g. lymphoma)
• Iodine def – goitre present
• Drugs – amiodarone, contrast media, iodines, litium + antithyroid medication
• Congenital – absence thyroid gland or dyshormonogenesis
• Infiltration of thyroid – amyloidosis, sarcoidosis, haemochromatosis

Question 4

What are the secondary causes

Answer 4

• Isolated TSH def
• Hypopituitarism – neoplasm, infiltrative, infection + radiotherapy
• Hypothalamic disorders – neoplasms + trauma

Question 5

What is the cause of transient hypothyroidism

Answer 5

• Withdrawal from thyroid suppressive therapy

- Postpartum thyroiditis (5-7% within first 6months postpartum)

Question 6

What are the details of Hashimoto’s thyroiditis

Answer 6

painless goitre w/ rubber consistency + irregular surface – function of thyroid varies

Question 7

What are the details for atrophic thyroiditis

Answer 7

represents end stage autoimmune hypothryroidism + pt +++ hypo

Question 8

What are the details of autoimmune thyroiditis

Answer 8

• Subclinical represents early stage of chronic thyroiditis + associated with normal function
• Excessive iodine can lead to this
• Uncommon in children – presents as delayed growth, facial maturation, puberty

Question 9

What are the details for subacute thyroiditis

Answer 9

Also granulomatois, giant cell or de Quervain’s thyroiditis

–> viral infection = local symptoms and ++ tenderness w/ nodularity

Question 10

What are the symptoms of hypothyroidism

Answer 10

• Tiredness, lethargy, intolerance to cold
• Dry skin
• Hair loss
• Slowing of intellectual activity e.g. poor memory + difficulty concentrating
• Constipation
• Reduced appetite w/ weight gain
• Deep hoarse voice
• Menorrhagia oligomenorrhoea or amenorrhoea
• Reduced libido
• Reduced hearing due to fluid in ear

Question 11

What are the signs of hypo

Answer 11

•	Dry coarse skin, hair loss + cold peripheries
•	Puffy face, hands + feet (myxedema)
•	Bradycardia
•	Delayed tendon reflexes
•	Carpal tunnel syndrome
•	 Serous cavity effusions e.g. pericarditis or pleural effusion
•	AKI
Can develop in myxoedema
•	Expressionless face w/ peri-orbital puffiness, swollen tongue, sparse hair
•	Enlarged heart
•	Megacolon/ intestinal obstruction
•      Encephalopathy

Question 12

What investigations do you perform

Answer 12

• Symptoms not specific to underactivity gland –> need TFTs
• Anti-thyroid peroxidase (anti-TPO) antibodies/ anti-thyroglobulin
• If asymmetrical goitre - imaging thyroid –> USS

Question 13

How do you treat hypothyroidism

Answer 13

• Need to lower TSH
• Levothyroxine (T4 or tetra-iodothyronine) – decrease dosages in pt w/ cardiac disease, severe hypothyroidism, +50 years
• Risk of T3 therapy + over-treatment w/ T4 = osteoporosis, cardiac arrhythmias
• Free T4 more useful in 2o hypo
• Ferrous sulfate, Ca supplements, rifampicin + amiodarone interfere with T4 absorption