Hyperthyroidism Flashcards
What is thyrotoxicosis?
The clinical effect of excess thyroid hormones, usually from gland hyperfunction.
Symptoms of hyperthyroidism
Diarrhoea Weight loss Increased appetite Over-active Sweats Heat intolerance Palpitations Tremor Irritability Labile emotions Oligomenorrhoea Infertility Rarely: Psychosis Chorea Panic Itch Alopecia Urticaria
Signs of hyperthyroidism
Pulse (fast/irregular)- AF, SVT, VT Warm moist skin Fine tremor Palmar erythema Thin hair Lid lag Lid retraction (exposure of sclera above the iris, causing stare) Hyperreflexia Goitre, thyroid nodules or bruit depeding on the cause
Signs of Grave’s disease
- Eye disease- exophthalmos, ophthalmoplegia
- Pretibial myxoedema- oedematous swellings above lateral malleoli
- Thyroid acropachy- extreme manifestation, with clubbing, painful finger and toe swelling and periosteal reaction in limb bones
Tests for hyperthyroidism
TSH (suppressed)
Free T4
Free T3
FBC (mild normocytic anaemia, mild neutropenia (Graves))
Raised ESR
Raised calcium levels
LFTs
Thyroid autoantibodies
Isotope scan if the causes are unclear to detect nodular disease or subacute thyroiditis
If ophthalmopathy, test visual fields, acuity and eye movements
Causes of hyperthyroidism
Grave's disease Toxic multinodular goitre Toxic adenoma Ectopic thyroid tissue Exogenous Subacute de Quervain's thyroiditis Self-limiting post-viral with painful goitre Amiodarone Lithium Postpartum TB
What is Grave’s disease?
Typical age- 40-60 years
Cause: Circulating IgG autoantibodies binding to and activating G-protein-coupled thyrotropin receptors which cause smooth thyroid enlargement and increased hormone production (esp. T3) and react with orbital autoantigens.
Triggers: Stress, infection, childbirth.
Patients are often hyperthyroid.
Linked to other autoimmune conditions-vitiligo, T1DM and Addison’s disease.
What is toxic multinodular goitre?
Seen in the elderly and in iodine-deficient areas.
There are nodules that secrete thyroid hormones.
Surgery is indicated for compressive symptoms from the enlarged thyroid.
What is toxic adenoma?
There is a solitary nodule producing thyroid hormones.
On isotope scan, the nodule is hot and the rest of the gland is suppressed.
What is ectopic thyroid tissue?
Metastatic follicular thyroid cancer or stroma ovarii.
Ovarian teratoma with thyroid tissue.
Exogenous causes of hyperthyroidism
Iodine excess
Food contamination
Contrast media
Levothyroxine excess
Treatment of hyperthyroidism
Beta-blockers (propranolol 40mg/6h) for rapid control of symptoms.
1)Antithyroid medication: two strategies (equally effective):
A) Titration, eg carbimazole 20–40mg/24h PO for 4wks, reduce according to TFTs every 1–2 months.
B) Block- replace: Give carbimazole + levothyroxine simultaneously (less risk of iatrogenic hypothyroidism).
In Graves’, maintain on either regimen for 12–18 months then withdraw. ~50% will relapse, requiring radioiodine or surgery.
Carbimazole SE: agranulocytosis (neutrophils, can lead to dangerous sepsis; rare (0.03%)); warn to stop and get an urgent FBC if signs of infection, eg sore throat/mouth ulcers.
Consider propylthiouracil for adults:
who experience adverse reactions to carbimazole
who are pregnant or trying to become pregnant within the following 6 months
with a history of pancreatitis.
2) Radioiodine ( 131I):
Most become hypothyroid post-treatment.
There is no evidence for increased risk of cancer, birth defects, or infertility in women.
CI: pregnancy, lactation.
Caution in active hyperthyroidism as there is a risk of thyroid storm.
Radioiodine can precipitate Grave’s ophthalmopathy and there is a complication of neck discomfort.
3) Thyroidectomy (usually total):
Carries risk of damage to the recurrent laryngeal nerve (hoarse voice) and hypoparathyroidism. Patients will become hypothyroid, so thyroid replacement needed.
4) In pregnancy and infancy: Get expert help.
Complications of hyperthyroidism
Heart failure Angina AF (seen in 10-25%) Osteoporosis Ophthalmopathy Gynaecomastia Thyroid storm
Which symptoms have the greatest ability to discriminate between euthyroidism and hypothyroidism?
Constipation
Myalgia and muscle weakness
Hoarse or deep voice
Cold intolerance
