Thyroid problems Flashcards
What does the thyroid secrete?
What is the active form of this, and where does it become active?
The thyroid secretes thyroxine T4 (Thyroid hormone) into the blood
Thyroxine is taken into cells and is metabolised into triiodothyronine T3 (Active form)
What does triiodothyronine do?
It increases cell metabolic activity, increases sympathetic activity, and promotes growth and development
What are the parathyroid glands responsible for?
Calcium metabolism
How is thyroid hormone regulated?
By a negative feedback loop
The hypothalamus signals the pituitary (using thyroid releasing hormone) to signal the thyroid (using thyroid stimulating hormone) to produce thyroxine to raise the level of blood thyroxine, and these hormones will stop secreting when blood thyroxine is too high.
This keeps thyroxine between 12-20 mmol/L in the blood
What can cause the thyroid to overproduce thyroxine?
Benign
- Obstruction
- Hyperthyroidism
Malignant
- Well and poorly-differentiated cancers
What is primary hyperthyroidism?
Hyperthyroidism originating from an issue within the gland
What is secondary hyperthyroidism?
Hyperthyroidism originating from the oversecretion of thyroid stimulating hormone
What is graves disease?
The most common cause of hyperthyroidism
An autoimmune condition in which antibodies that mimic thyroid stimulating hormone are created
What are some symptoms of Graves disease?
Exophthalmos (bulging eyeballs)
- Swelling and hypertrophy of muscles behind eyes due to overproduction of thyroxine
Pretibial myxoedema (specific to graves)
- Deposits of mucin underneath the skin which can become waxy and discoloured
What is a solitary toxic thyroid nodule?
What is Plummer’s disease?
Solitary toxic thyroid nodule: A single abnormal thyroid nodule overproducing thyroxine which can be fixed by surgical removal of the single nodule
Plummer’s disease: The formation of a toxic multinodular goitre
What is de quervains thyroiditis?
What is the progression of this?
A viral infection of the thyroid
As the infection progresses the patient will naturally go from hyperthyroid phase, to hypothyroid phase to normal
What are some symptoms of hyperthyroidism?
All related to increased metabolic activity
Anxiety and irritability
Sweating and heat intolerance
Tachycardia
Weight loss
Sexual dysfunction
Frequent loose stools
Fatigue
What is the first line treatment for hyperthyroidism?
Carbimazole - Inhibits thyroxine production.
Takes between 4-8 weeks to normalise thyroid function
What are alternative management options for hyperthyroidism?
Radioactive iodine
- Thyroid absorbs radioactive iodine, which destroys thyroid cells resulting in reduced thyroid hormone production
Beta-blockers
- Doesn’t treat hyperthyroidism
- Treats symptoms associated with hyperthyroidism
Surgery
- Hemithyroidectomy or total thyroidectomy
- Levothyroxine supplementation for life after total thyroidectomy
What are some physical signs of hypocalcemia?
How do you know for sure?
Chvostek’s sign
- Tapping facial nerve causes face twitching
Trousseau’s sign
- Squeezing bicep past systolic pressure causes wrist flexion
Blood test to definitively check for hypocalcemia
