Thyroid Flashcards
(30 cards)
What is the location of the thyroid?
In the anterior neck between the C5 and T1 vertebra
Are males or females more affected by thryoid disease?
Females (about 5-10 times as much)
What is the definition of thyrotoxicosis?
Excess thyroid hormone in the blood
What is the definition of hyperthyroidism?
Overproduction of thyroid hormone
What is the definition of hypothyroidism?
Under production of thyroid hormone
Give 3 reasons for increased levels of thyroid hormone
- Hyperthyroidism
- Leakage of preformed hormone from the thyroid (due to autoimmune of infection destruction of the follicular cells)
- Ingestion of excess thyroid hormone
Give 4 predisposing factors to thyroid autoimmunity
- Genetics e.g. HLA
- Environment (including diet, smoking, stress, iodine levels etc)
- Endogenous factors e.g. sex hormones, glucocorticoids, pregnancy
- Being female
What are the 2 main antibodies involved in thyroid autoimmunity?
Thyroglobulin and thyroid peroxidases (TPO) antibodies
How is thyroid cell destruction mediated?
By cytotoxic T cell (CD8+)
What is a goitre?
A palpable and visible thyroid enlargement due to a variety of causes
What are the 2 types of goitre?
- Diffuse smooth
2. Nodular (multi and single)
What are some causes of a diffuse smooth goitre?
- Graves’ disease
- Thyroiditis
- Iodine deficiency
- Medications (e.g. lithium, amiodarone)
- Hereditary factors
What are some causes of a single nodular goitre?
- Cyst
- Adenoma
- Carcinoma
- Other rare causes
What is the difference between primary and secondary hyperthyroidism?
Primary is due to a thyroid pathology whereas secondary is due to thyroid stimulation by excess TSH
What is the most common cause of hyperthyroidism?
Graves’ disease
Give the 3 more common causes of hyperthyroidism
- Graves’ disease (most common – 75-80% of cases)
- Toxic multinodular goitre
- Toxic adenoma (benign)
Give some less common causes of hyperthyroidism
- Exogenous/drug induced (iodine/T4 excess)
- Ectopic thyroid tissue (metastases)
- Subacute, postpartum and silent thyroiditis
Give some clinical features of hyperthyroidism
- Weight loss
- Tachycardia
- Hyperphagia (excessive eating)
- Anxiety
- Tremor
- Heat intolerance
- Sweating
- Diarrhoea
- Menstrual disturbance
- Lid lag and ‘stare’
How would you investigate and diagnose hyperthyroidism?
- Thyroid function tests
- Thyroid antibodies
- Isotope uptake scan
- Diagnosis of underlying cause
- Clinical history and physical signs
What would you expect to see from the TFTs of primary and secondary hyperthyroidism?
- Primary: increased [free T4], increased [free T3], supressed TSH
- Secondary: increased [free T4], increased [free T3], inappropriately high TSH
How would you treat hyperthyroidism?
- Beta blockers for rapid symptom control
- Anti-thyroid drugs (a course or long-term)
- Radioiodine (I-131)
- Surgery
What is the most common cause of primary hypothyroidism?
Iodine deficiency
Give some causes of primary hypothyroidism
- Autoimmune/atrophic hypothyroidism
- Hashimoto’s thyroiditis
- I-131 therapy
- Thyroidectomy
- Post-partum thyroiditis
- Iodine deficiency
- Drug induced e.g. carbimazole, lithium, amiodarone
- Thyroid hormone resistance
What causes secondary hypothyroidism?
Pituitary or hypothalamic disease
