Hypothyroidism

Question 1

Define:

Answer 1

The clinical syndrome resulting from insufficient secretion of thyroid hormones.

Question 2

Aetiology/risk factors of primary acquired:

Answer 2

Primary - decreased thyroid function

-Primary atrophic hypothyroidism: lymphocytic infiltration of the thyroid, leading to atrophy, no goitre
• Hashimoto’s thyroiditis (autoimmune): goitre due to lymphocytic and plasma cell infiltration
• Iatrogenic (post-thyroidectomy, radioiodine, hyperthyroid medication, amiodarone, lithium, iodine)
• Severe iodine deficiency (chief cause worldwide)
• Iodine excess (Wolff-Chaikoff effect)
• Thyroiditis (subacute – temporary hypothyroidism after hyperthyroid phase)

Question 3

Aetiology/risk factors of primary congenital:

Answer 3

• Thyroid dysgenesis

* Inherited defects in thyroid hormone biosynthesis

Question 4

Aetiology/risk factors of secondary:

Answer 4

o Pituitary and Hypothalamic Disease - resulting in reduced TSH and TRH and, hence, reduced stimulation of thyroid hormone production

Question 5

Epidemiology:

Answer 5

0.1-2% in adults

6x more common in females

Peak incidence occurs >40 years

Iodine deficiency in those living in mountainous areas

Question 6

Symptoms:

Answer 6

EVERYTHING SLOWS DOWN

Insidious onset

Weight gain

Loss of appetite

Intolerance to cold

Lethargy

Mental slowness

Hoarseness

Irregular or absent periods

parasthesia

Depression

Constipation

Cramps

Ataxia

Dry skin

Hyperthyroid treatment

Question 7

Symptoms of myxoedema coma:

Answer 7

Hypothermia 
Heart failure 
Hypoventilation 
Hyopnatremia 
Confusion 
Coma

Question 8

Signs:

Answer 8

Hands:

• Cold hands
• Bradycardia

Face/neck:

• Goitre
• oedema
• pale puffy face
• vitiligo
• dry skin

Chest:

• pericardial effusion
• Pleural effusion

Nerves:

• Slow reflexes
• Carpal tunnel

Abdo:
-Ascites

Question 9

Investigations:

Answer 9

Bloods:

T3/T4 - will be low in both primary and secondary

TSH - will be low in myxoedema and primary BUT high in secondary.

FBC - may show normocytic anaemia

Cholesterol - may be high

U + E’s - may have low sodium

Question 10

Management of hypothyroidism:

Answer 10

Levothyroxine (T4)
-insure that you have excluded adrenal insufficiency as can lead to Addison’s (want to normalise levels but not suppress TSH)

-In secondary do not use levels of TSH as a measure must use free T4

Question 11

Management of myxoedema coma:

Answer 11

Oxygen 
Rewarming 
Rehydration 
IV T3/4 (liothyronine (IV T3))
Treat underlying cause (e.g. infection)

Question 12

Complications:

Answer 12

Myxoedema coma

Myxoedema madness (psychosis with delusions, hallucination and dementia)

Question 13

Prognosis:

Answer 13

Will have to have to take levothyroxine for life

Myxoedema will have 80% mortality