Hypothyroidism + Thyroid Tumours Flashcards
What are the causes of hypothyroidism?
Hashimoto’s thyroiditis
Iodine deficiency
Secondary to any treatment for hyperthyroidism
Medications
Hypopituitarism (secondary hypothyroidism)
Which medications might cause hypothyroidism?
Lithium
- causes goitre + hypothyroidism
Amiodarone
- usually causes hypothyroidism, but can cause thyrotoxicosis
What are the clinical features of hypothyroidism?
Weight gain Fatigue Dry skin Coarse hair + hair loss Fluid retention (oedema, pleural effusions, ascites) Heavy/irregular periods Constipation
What would blood tests show in primary + secondary hypothyroidism?
Primary: - T3 + T4 low - TSH high Secondary: - T3 + T4 low - TSH low
What is the treatment for hypothyroidism?
Levothyroxine
- titrate until TSH levels normal
- if TSH levels high, dose is too low
- if TSH levels low, dose is too high
What is levothyroxine?
Synthetic T4, metabolises to T3 in the body
What are the features of Hashimoto’s thyroiditis?
Most common cause of hypothyroidism in developed world
Autoimmune
Anti-TPO + antithyroglobulin antibodies
Initially causes a goitre, but then atrophy of thyroid gland
What is the most common cause of hypothyroidism in the developing world?
Iodine deficiency
Which advice should be given to patients regarding when to take their levothyroxine?
Take on an empty stomach, at least 30 mins before breakfast, caffeine or other drugs which might interfere with absorption
Which drugs might impair absorption of levothyroxine?
Calcium carbonate
Antacids
Iron supplements
Which patients might require a lower dose of levothyroxine initially?
Elderly + those with IHD –> risk of MI
start at low dose and build up
How should levothyroxine dose be altered during pregnancy?
Should be increased by 50% in the first trimester
What are the complications of hypothyroidism?
Myxoedema coma
If chronic:
- heart disease
- dementia
What are the complications of hypothyroidism during pregnancy?
Eclampsia
Anaemia
Prematurity
SGA baby
What is myxoedema come?
Severe, acute hypothyroidism –> 50% mortality
What are the clinical features of myxoedema coma?
Often follows illness (infection, stroke, seizure, surgery) or medication (sedatives):
- hypothermia
- neuro: reduced reflexes, seizures, coma
- hypoglycaemia
- bradycardia
What is the treatment for myxoedema coma?
IV T3
Corticosteroids as Addison’s may be present, either as alternative diagnosis or co-morbid hypopituitarism
What is sick euthyroid syndrome?
Abnormal TFTs during a non-thyroid illness
routine TFTs during illness is not recommended
What are the different types of thyroid tumours?
Benign: - adenomas Carcinomas: - papillary - follicular - medullary - anaplastic
How are thyroid adenomas classified?
Functioning: - releases hormones - 'hot' on radioisotope scan Non-functioning: - 'cold' on radioisotope scan
What is the management of thyroid adenomas? Why?
Hemithyroidectomy + histological analysis
- most are follicular adenomas which cannot be distinguished from follicular carcinoma on FNA
What is the most common thyroid cancer?
Papillary carcinoma
What are the clinical features of papillary thyroid carcinoma?
Young patients
May spread to cervical lymph nodes
Excellent prognosis
How is papillary thyroid carcinoma treated?
Hemithyroidectomy for histology
Followed by completion thyroidectomy (if >1cm)
Then radio iodine
(can do initial thyroidectomy if FNA cytology is definitive)
