What is the location of the thyroid gland?
Located in the neck
The thyroid gland has a left and right lobe with a central isthmus, giving it a butterfly-shaped appearance.
What are the active thyroid hormones produced by the thyroid gland?
- T3
- T4
The thyroid gland produces and stores these hormones, which regulate metabolism.
What is the physiological effect of thyroid hormones on metabolism?
Increases cell metabolism via nuclear receptors
Thyroid hormones are vital for growth and mental development.
What is the normal range for TSH in thyroid function tests?
0.4-4.2 mU/L
This range is used to assess thyroid function in common disorders.
What are the common causes of hyperthyroidism?
- Graves disease
- Toxic multinodular goitre
- Toxic adenoma
- Thyroiditis
- Drug induced
- Hyperemesis gravidarum
- TSH secreting pituitary tumour
- Thyrotoxicosis factitial
- Pituitary resistance to thyroid hormone
- Molar pregnancy
Graves disease is the most common cause of primary hyperthyroidism.
What is the most common cause of primary hypothyroidism?
Chronic autoimmune thyroiditis
This condition can present in two forms: Hashimoto’s thyroiditis (goitre present) and atrophic thyroiditis (no enlargement).
What are the clinical features of hyperthyroidism?
- Heat intolerance
- Weight loss
- Weakness/fatigue
- Eye signs (lid lag and stare)
- Tachycardia/AF
- Tremor
- Warm moist skin
- Thyroid enlargement
Symptoms depend on the duration of the disease and the degree of hormone excess.
What are the diagnostic criteria for hyperthyroidism?
- Serum TSH: below normal
- Free T4: Raised
- Free T3: Raised
Occasionally, Free T4 may be normal while Free T3 is raised.
What are the symptoms of hypothyroidism?
- Periorbital oedema
- Cool, dry skin
- Coarse hair
- Bradycardia
- Mental slowness
- Mild obesity
Other symptoms may include non-pitting oedema and loss of eyebrows.
What is the management for primary hypothyroidism?
Lifelong thyroid hormone therapy (levothyroxine)
Regular measurement of serum TSH is essential for monitoring.
What are the clinical features of hypothyroidism?
- Depression
- Fatigue
- Weight gain
- Cold intolerance
- Dry, itchy skin
- Bradycardia
- Goitre possible
Symptoms contrast with those of hyperthyroidism.
What is a thyroid crisis or thyroid storm?
Rare condition with rapid deterioration of hyperthyroidism
Symptoms include hyperpyrexia, severe tachycardia, and extreme restlessness.
What is a non-toxic goitre?
Generalized enlargement of the thyroid gland without abnormal secretion function
Most common cause is iodine deficiency.
What is the management for large goitres causing obstructive symptoms?
Surgical excision
Iodine supplementation may also be required.
