Describe thyroid dysfunction caused by excess in thyroid hormone
- Excess thyroid hormone - hyperthyroidism
- primary: common
- secondary: rare
- thyrotoxicosis can occur without hyperthyroidism
- usually due to weight loss attempts using excess thyroid replacing hormone
Describe thyroid dysfunction caused by a deficiency in thyroid hormone
- Deficiency - hypothyroidism
- primary: common
- secondary: less common
What are causes of hyperthyroidism?
- Graves’ disease - 70-80% of cases
- autoantibodies stimulating TSH receptor: results in excess hormone release - Toxic multi-nodular goitre
- Toxic adenoma
- tumour within the thyroid gland which stimulates unregulated release of thyroid hormone resulting in hyperthyroidism - Pituitary tumour (rare)
- produces excess TSH which makes the thyroid gland produce too much hormone
What are signs of hyperthyroidism?
- Signs
•warm moist skin
- increased metabolism results in more heat generation
•tachycardia and atrial fibrillation
•increased blood pressure and heart failure
•tremor and hyperreflexia
• eyelid retraction and lid lag
- in lid lag the eyeball moves down and exposes white sclera of the eye before the eyelid can catch up
What are symptoms of hyperthyroidism?
- Hot and excess sweating, weight loss, diarrhoea
- Palpitations, muscle weakness
- Irritable, manic, anxious
List some diseases which are often found in the family history of patients with Graves’ disease
- Vitiligo
- Pernicious anaemia
- Type 1 diabetes mellitus
- Coeliac disease
- Myaesthenia gravis
What other clinical features are associated with Graves’ disease?
- Diffuse goitre (enlarged thyroid gland)
- Opthalmopthy
- sceral injection
- proptosis
- periorbital oedema - Conjunctival oedema
- chemosis
Describe primary hypothyroidism
- Autoimmune (hashimoto’s) thyroiditis (90% of cases)
- Idiopathic atrophy
- Radioiodine treatment/thyroidectomy surgery
- excessive thyroid tissue removed results in hypothyroidism
- radioiodine treatments reduce thyroid secretion which can lead to atrophy of the thyroid gland - Iodine deficiency
- Drugs
- carbimazole, amiodarone, lithium - Congenital
Describe Hashimoto’s thyroiditis
- Autoimmune
- antibodies attack the thyroid gland resulting in inflammation which causes gradual fibrosis and destruction of specialised thyroid tissue
Describe secondary hypothyroidism
- Caused by hypothalamic/pituitary disease
What are signs of hypothyroidism?
- Dry coarse skin
- Bradycardia, hyperlipidaemia
- Psychiatric or confusion
- Goitre (hashimoto’s)
- Delayed reflexes
What are symptoms of hypothyroidism?
- Tired
- Cold intolerance, weight gain, constipation
- Hoarse voice, goitre, puffed face and extremities
- Angina
- ‘Slow’, poor memory
- Hair loss
What are causes of hypothyroidism?
1.Hashimoto’s thyroiditis
2. Idiopathic atrophy
3. Iodine deficiency
4.
What group is most susceptible to Hashimoto’s thyroiditis and how does it present + what is it associated with?
- Middle Aged and elderly woman
- Presenting features
- goitre
- hypothyroid features - Associations
- often a family history of autoimmune disease
(Vitiligo, PA, type 1 DM, Addison’s disease)
- Down’s syndrome
Describe the epidemiology of idiopathic atrophy
- Increased incidence with age
- 10x more in females
- Likely autoimmune cause
- lymphocyte infiltrate
- associated with organ specific autoimmune disease
What are the 3 main investigations methods for thyroid disease?
- Blood
- TSH, T3 and T4 - Imaging
- ultrasound scan (cysts)
- radioisotope scans - gland uptake - Tissue
- fine needle aspirate/biopsy (FNA and FNB)
Describe the hormone levels in pituitary and graves or adenoma hyperthyroidism
- Pituitary cause
- raised TSH
- raised T3 - Graves or adenoma
- low TSH
- raised T3
(Due to fact that pituitary is still functional so reduces TSH secretion)
Describe hormone levels with a pituitary caused and gland failure caused hypothyroidism
- Pituitary cause
- low TSH
- low T4 - Gland failure
- high TSH
- low T4
What are drug treatments for hyperthyroidism?
- Carbimazole
- titration
- block and replace - T4 as required - Beta-blockers
- Radioiodine- 131I
- hypothyroid risk with time - review
What other treatments are available for hyperthyroidism?
- Surgery - partial thyroidectomy
- usually follows drug therapy to stabilise - Graves’ opthalmopathy - none/simple measures
What are treatments for hypothyroidism?
- Give T4 tablets (thyroxine)
- slow response - weeks
• increase dose slowly
- IHD
• recheck using TSH as a guide of gland failed
Describe goitre
- Diffuse enlargement of the thyroid gland
- often iodine deficient (mountainous are as of developing countries
- diffuse, nodular
- potentially drug related
What other change apart from goitre can occur in the thyroid?
- Solitary nodule enlargement
- adenoma, carcinoma, cyst formation possible
- low cancer risk, however it is suspicious in children or elderly
What feature is often present in thyroid cancer?
Thyroid swelling
