Hypothyroidism

Question 1

Define hypothyroidism

Answer 1

Syndrome resulting from insufficient secretion of thyroid hormones T4 (<10.2) and T3 (<3.2)

Question 2

Aetiology of hypothyroidism

Answer 2

Primary (TSH high)
- Hashimoto’s (Autoimmune)
- Subacute/De Quervain’s thyroiditis
- Riedel thyroiditis
- DiGeorge Syndrome
- Iatrogenic (post surgery/radioiodine)
- Severe iodine deficiency or excess
- Drugs - lithium, amiodarone, interferon-a, thalidomide, tyrosine kinase inhibitors

Secondary (low TSH)
- Pituitary/hypothalamic disease e.g. tumour
- Thyroid hormone resistance

Question 3

What are the risk factors for hypothyroidism

Answer 3

Iodine deficiency
Female sex
Middle age
Family history of autoimmune thyroiditis
PMHx autoimmune disorders
Graves’
Post-partum thyroiditis
Turner’s and Down’s syndromes
Primary pulmonary hypertension
MS
Radiotherapy

Question 4

What are the phases of De Quervain’s thyroiditis

Answer 4

1. Hyperthyroidism, painful goitre, raised ESR (3-6 weeks)
2. Euthyroid (1-3 weeks)
3. Hypothyroidism (weeks-months)
4. Thyroid structure and function normal

Question 5

What are the symptoms of hypothyroidism

Answer 5

Cold intolerance
Deepening voice
Constipation
Bradycardia
Weakness or myalgia
Lethargy, depression
Weight gain (but reduced appetite)
Menstrual irregularity
Eyelid or facial oedema, dry or coarse skin
Thick tongue

Question 6

What are the signs and symptoms of myxoedema coma

Answer 6

Hypothermia
Hypoventilation
Confusion
Coma
LMN signs (differentiates from stroke)
Hyponatraemia
Heart failure

Precipitating factors: Infection, MI, stroke, trauma

Question 7

What are the signs of hypothyroidism on examination

Answer 7

Hands: bradycardia, cold
Head/neck/skin: pale and puffy face, goitre (Hashimoto’s), oedema, hair loss, dry skin, vitiligo
Chest: pericardial or pleural effusion
Abdomen: ascites
Neurological: slow relaxation of reflexes, signs of carpal tunnel syndrome

Question 8

What investigations should be done for hypothyroidism

Answer 8

ECG: ?HF

TFTs
Thyroid antibodies (TPO and TG)
FBC: ?anaemia
U&Es: ?hypoNa
Cholesterol: elevated
Glucose: ?T1DM (ass. with primary hypoT)

Thyroid scintigraphy: Globally reduced uptake
Pituitary function testing: ?secondary hypoT

Question 9

What is the management for hypothyroidism

Answer 9

Thyroxine replacement: Levothyroxine sodium PO 50 micrograms/day - 50 (25 in elderly or IHD)
- Primary: use TSH to guide
- Secondary: use fT4 to guide (middle of reference range)

Question 10

What is the management for de Quervain’s thyroiditis

Answer 10

Self-limiting
Aspirin or NSAIDs for pain
Steroids if severe

Question 11

What is the management for myxoedema coma

Answer 11

1. Oxygen
2. Rewarming
3. Rehydration (IV fluids)
4. IV T4/T3 liothyronine sodium then levothyroxine
5. IV hydrocortisone

Question 12

What are the complications of hypothyroidism

Answer 12

Hyponatraemia
Myxoedema coma
Myxoedema madness (psychosis with delusions and hallucinations or dementia
Angina or AF
Osteoporosis
Resistant hypothyroidism
Pregnancy complications
Sick Sinus syndrome (alternating bradycardia and tachycardia)

Question 13

What is the prognosis for hypothyroidism

Answer 13

Lifelong therapy required
Generally excellent prognosis with full recovery if treated
Myxoedema coma has mortality of up to 80%