Thyroid Hormones

A set of flashcards covering key terms related to thyroid hormones, their functions, disorders, and related tests.

Thyroid Hormones

Regulate metabolism, promote growth, and are essential for normal CNS function, increase O2 consumption

Tri-iodothyronine (T3)

A thyroid hormone that is four times more active than thyroxine (T4) and has a half-life of 1.5 days.

Thyroxine (T4)

A thyroid hormone with a half-life of 9 days that can be converted into T3 in tissues.

Negative Feedback Control

A regulatory mechanism in which TSH and TRH levels are controlled based on free T3 and T4 concentrations.

Hypothyroidism

A condition characterized by low thyroid hormone levels, affecting about 2% of women and 0.2% of men in the UK.

Hashimoto's Thyroiditis

An autoimmune condition where the immune system attacks the thyroid gland, leading to hypothyroidism.

Total T3

The total amount of tri-iodothyronine in the bloodstream, used to evaluate thyroid function.

Graves' Disease

An autoimmune disorder that is a common cause of hyperthyroidism, characterized by excessive thyroid hormone production.

Hyperthyroidism

A condition characterized by excessive thyroid hormone levels, affecting approximately 1% of women and 0.1% of men in the UK.

Thyroid Function Tests

Tests that measure levels of total T3, T4, and TSH to assess thyroid function and diagnose disorders.

Hypothyroidism Causes

• Post thyroidectomy

• Ant thyroid drugs

• Congenital hypothyroidism

• Iodine deficiency

Hypothyroidism symptoms

• Weight gain

• Deep voice

• Low appetite

• Cold intolerance

• Bradycardia

• Constipation

Hyperthyroidism symptoms

• Weight loss

• Hyperkinesis

• Sweaty

• Tachycardia

• Diarrhoea

• Heat intolerance

Hyperthyroidism causes

• Graves

• Toxic nodules

• Ectopic thyroid tissue

• TSH secreting tumours

Hyperthyroidism management

• anti thyroid drugs

• Radioiodine therapy

• Thyroidectomy

Non - thyroidal illness tests

• thyroid reg disturbed

• Conversion T4 to reverse T3 so both low

• TSH low or norm

• Wait until recovery before testing function

TBG

Increase

• total T4/3

• Pregnancy

• Inherited TBG excess

• Oral

Decrease

• severe illness

• Protein loss

• Malnutrition

• Androgens

• Cushings