Flashcards in Endo-Repro L14 Thyroid drugs Deck (16):
1
Thyroid hormone synthesis and secretion: (8 steps)
1. Iodide building block using ATP Na+ iodide symporter – taken into cell.
2. Pendride → Cl- iodide transported – colloid.
3. Uptake of iodide
4. Iodination and coupling
5. Endocytosis and secretion
6. Vesicle fuses w/ lysosomes
7. Breakdown of protein → T3/4 released
8. MIt/DIT taken up by colloid to reuse
2
Regulation of thyroid hormone release:
1. Cold, trauma and stress input into the hypothalamus.
2. Hypothalamus releases TRH which stimulates the anterior pituitary
3. The Anterior pituitary releases TSH which stimulates the thyroid to make and release T3/4
a. Binds via GPCR
4. T3/4 negatively feedback to the pituitary
3
Actions of thyroid hormone:
1. Calorigenesis → degeneration of heat
2. Increased Metabolism → production and use of energy
3. Growth and maturation
4. Cardiovascular effects
4
Hypothyroidism: Causes
Primary → autoimmune thyroiditis or iodiopathic atrophy.
Secondary → affecting anterior pituitary
Tertiary → affecting the hypothalamus
Iodine defiency → diet related → increased release of TSH
Natural goitrogens → interfere with iodine uptake.
5
Hypothyroidism: Symptoms
Cretinism in young
Myxoedema in adult:
1. Lethargy
2. Cold intolerant
3. Weight gain
4. Cold, raw skin
5. Husky voice
6. Muscle weakness
6
Hypothyroidism:Diagnosis → Can measure
1. Increased levels of TSH
2. Thyroglobulin (TgAB) antibodies (lymphocytic thyroidism)
3. Reduced T3/4 levels (can’t always measure)
4. Hypercholestraemia
7
Hypothyroidism: Treatment – mainly replacement
• Levothyroxine sodium, T4 → given orally, standard treatment.
• Tri-iodothyronine, liothyronine, T3 (more difficult to manage as has quick high spikes)
• Iodide (sodium or potassium iodide
8
Hyperthyroidism (Thyrotoxicosis): Common Causes
• Grave’s disease
• Tumours of the thyroid gland
9
Hyperthyroidism (Thyrotoxicosis): Symptoms
Nervousness
Irritability
Increased perspiration
Heart racing
Hand tremors
Anxiety
Difficulty sleeping
Thinning of the skin
Fine brittle hair
Muscular weakness
10
Hyperthyroidism (Thyrotoxicosis): Diagnosis
Symptoms of hyperthyroidism
Mass at base of neck
Increased levels of T4
Decreased levels of TSH
11
Hyperthyroidism (Thyrotoxicosis): Treatment
Drugs that inhibit T3/4 secretion
High disease of iodide
Thyroidectomy
Beta-adrenergic receptor antagonist (propranolol)
Radio iodine
12
Hyperthyroidism (Thyrotoxicosis): Drugs that inhibit T3/4 secretion
Thiureylenes
Carbimazole
Methimazole
Felimazole
13
High disease of iodide
Reduced synthesis and release of thyroid hormones (unsure why)
14
Radio iodine
Concentrated in thyroid gland destroys follicle cells → beta radiation
15
Beta-adrenergic receptor antagonist (propranolol)
Doesn’t change hormone concentration but blocks effect on here.
16