Hyperthyroidism Flashcards
Hyperthyroidism Definition
The clinical condition is caused by increased circulating free levels of thyroid hormones. Aka thyrotoxicosis
Hyperthyroidism Epidemiology
The prevalence is 2%. It is more common in females (5:1) and middle age (Graves’). TMG is the most common in older females
Hyperthyroidism Causes
- Graves’ disease (75%)
- Toxic Multinodular Goitre (15%)
- Toxic Adenoma (5%)
- Hashimoto’s thyroiditis
- Exogenous
- Iodine excess
- Food contamination
- Contrast media
- Excess thyroxine
- Iodine excess
- Other
- Subacute de Quervain’s Thyroiditis
- Drugs
- Amiodarone
- Lithium (more commonly hypothyroidism)
- Postpartum
- TB
Define Graves’s Disease
An autoimmune condition in a genetically susceptible person resulting from the interaction of antibodies to IgG thyroid-stimulating hormone (TSH) receptors, causing thyroid gland stimulation
Define Toxic Multinodular Goitre
A goitre contains multiple autonomously functioning nodules, resulting in hyperthyroidism. These function independently of TSH and almost always begin benign. However, non-functioning thyroid nodules in the same goitre may be malignant
Define Adenoma
‘Single nodular goitre’ An autonomous hyper functioning nodule that produces excess thyroid hormone and suppresses TSH activity. Those nodules are almost always benign
Define Hashimoto’s thyroiditis
Autoimmune disorder that may produce hyperthyroidism then hypothyroidism
Pathogenesis of Graves’ Disease
There is uniform enlargement of the thyroid, which may reach several times the normal size. The follicular epithelium is hyper plastic and may show papillary infoldings. The tan colour of normal thyroid, due to stored colloid is missing.
Graves’ Disease
- Broken down colloid (cannot store the colloid)
- Hyperplastic epithelium
Hyperthyroidism Clinical Presentation
THYROIDISM:
- Tremor
- Heart rate up
- Yawning [fatigability]
- Restlessness
- Oligomenorrhea & amenorrhea
- Intolerance to heat
- Diarrhea
- Irritability
- Sweating
- Musle wasting & weight loss
- Exophthalmos
- In Graves’
- Ophthalmopathy
- Gritty eyes and lid lag
- Preorbital oedema
- Diplopia
- Pretibial myxoedema (0.5%)
- Clubbing
- Ophthalmopathy
- In Graves’
Hyperthyroidism Investigations
- TFTs
- Thyroid autoantibodies
- Imaging
- Thyroid uptake scans
TFTs in Hyperthyroidism
TSH - Primary - decrease - Secondary - increase T4 - Primary & Secondary - Increase T3 - Primary & Secondary - Increase
Thyroid autoantibodies investigations in hyperthyroidism
- Thyroid autoantibodies
* Anti-Thyroid Peroxidase (Anti-TPO) and Anti-Thyroglobulin Antibodies (ATA)
* Suggest autoimmune cause (i.e. Graves’ or Hashimoto’s)* TSH-receptor antibody * Graves’ disease
Thyroid uptake scans for hyperthyroidism types
Graves - bright diffuse uptake TMG - multiple bright uptake areas Adenoma - single bright uptake focus Thyroiditis - Diffuse uptake
Hyperthyroidism Management
Severe
- One of either
- Carbimazole
- Block hormone synthesis
- Propylthiouracil
- Block hormone synthesis
- Inhibits peripheral T4 conversion to T3
- Carbimazole
Mild-Moderate
- One of either
- Carbimazole
- Propylthiouracil (at lower doses)
Relapse
- Radioactive iodine
- Surgery
Define Thyroid Storm
Severe hyperthyroidism amplified by a factor, such as infection or physical stress. It affects 2% of patients and has a mortality of 10-20%
