Hypo and Hyperthyroidism Flashcards
What is hyperthyroidism
Due to excess T3 and T4
Is hyperthyroidism usually caused by excess TSH
No, this is very rare
What is the most common cause of hyperthyroidism
Graves’ disease
What is thyrotoxicosis
Clinical syndrome resulting from the effect on the tissues due to circulating T3 and T4 - increased metabolic rate
What three diseases usually result in hyperthyroidism
- Graves’ thyroiditis
- Functioning adenoma
- Toxic nodular goitre
What is strums ovarii
A rare tumour in which thyroid hormones are produced and released into the blood - leading to an excess
Signs of Graves’ thyroiditis
- Associated with diffuse goitre
- Thyroid is enlarged, firm and red
- Hyperplasia of acing epithelium
- Reduction in colloid
- Accumulation of lymphocytes in lymphoid follicle formation
Why does the thyroid appear red in Graves’ thyroiditis
Due to increased vascularisation
How does Graves’ thyroiditis occur
IgG are produced (autoimmune) which bind to thyroid epithelial cells and stimulates it like TSH would - stimulatory hypersensitivity
What are the IgG autoantibodies known as
LATS - Long-acting thyroid hypersensitivity
Symptoms of individuals with Graves’ thyroiditis
- Exopthalmos (bulging of eyes due to deposition of fat in retrobulbal area + inflammatio/oedema of extra-ocular muscles) - MOST COMMON
- Accumulation of mucopolysaccharides in dermis
- Finger clubbing
Do adipocytes have receptors to TSH
Yes
What is nodular goitre
Thyroid enlarges (usually due to iodine deficiency)
How does hypothyroidism effect the metabolic rate
Lowers it
Symptoms of hypothyroidism
- Accumulation of mucopolysaccharides in the face - myxoedema face
How does hypothyroidism effect a newborn
- Physical growth and mental development impaired - Cretinism
Where is cretinism common
Areas where diet contains insufficient iodine for thyroid hormone synthesis
What is the most common cause of hypothyroidism
Hashimoto’s thyroiditis
Describe some iatrogenic causes of hypothyroidism
- Removal of the thyroid surgically
2. Certain drugs causing it as a side-effect
What is myxoedema
swelling of the skin and underlying tissues giving a waxy consistency
What can happen to the thyroid later on in patients with hypothyroidism
Atrophy and fibrosis
Appearance of the thyroid during hypothyroidism
- Firm, fleshy and pale
- Densley infiltrated by plasma cells and lymphocytes with lymphocytic colloid formation
- reduction in colloids
- Thyroid epithelial cells enlarge and develop eosinophilic granular cytoplasm
Why do thyroid epithelial cells develop eosinophilic granular cytoplasms in hypothyroidism and what are they now known as
Due to proliferation of mitochondria
Askanazy cells