Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharmacy Year 3 > Thyroid > Flashcards

Thyroid Flashcards

1
Q

What do thyroid follicular cells secrete?

A

T3 and T4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are parafollicular C cells responsible for?

A

Section of calcitonin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does thyroglobulin contain?

A

Iodide to supply thyroid hormones for 90 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What effect does TSH have on thyroid follicular cells?

A

Stimulates thyroid follicular cells to produce thyronine hormones (T3 and T4)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What role of cAMP have on thyroid cells?

A

Activates functional aspects of thyroid cells e.g.
Thyroglobulin synthesis
Iodide pumping
Iodination by thyroid peroxidase
Endocytosis, proteolysis and hormone release

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the process of iodide transport in follicular cells

A

Iodide ions are transported from the bloodstream into cells via NIS which transports 2Na+ or each I- anion into the cell

Iodide ions are transported from the cells into the lumen via Pendrin transporter

Once inside the lumen, I- is oxidised into atomic iodine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the action of thyroid peroxidase enzyme

A

TPO spends the apical membrane and is responsible for the iodination of thyroglobulin

TPO adds iodide onto thyroglobulin backbone - consists of tyrosine residues. Can be added in 2 different places to give mono/di-iodotyrosine

Iodinated thyroglobulin is taken into cells by endocytosis,. Proteolysis occurs by lysosomes which release T2 and T4 from the backbone of thyroglobulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Give examples of 2 thyroid hormones

Discuss their abundance/characteristics

A

Thyronine - T3: more active/potent
Thyroxine - T4: major form in the blood and has a longer half life than T3

T4 can be converted to T3 as required to protect the body from excess

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which drugs are used to treat hypothyroidism?

A

Levothyroxine sodium T4: tablets or oral solution

Liothyronine T3: tablets or slow iv infusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which drugs are used to treat hyperthyroidism?

A

Carbimazole

Propylthiouracil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the characteristics of thyroxine

A

Insoluble in serum - transported in serum in conjunction with specific binding proteins which are synthesised in the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What effect does lover disease have on T4?

A

Loss of effective T4 transport to peripheral tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How doe thyroid hormones enter cells?

A

Via specific transporters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the location and actions of iodothyronine deiodinases

A

DIO1 - predominant in the liver, kidney and muscle. Also found in thyroid. Produces most of the circulating T3

DIO2 - predominant in areas of CNS and pituitary thryrotropes. Controls intercellular T3 concentration. Important for feedback regulation. Found in skeletal muscle in some species

DIO3 - produces inactive rT3 and prevents thyroid hormone access to specific tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where are thyroid hormone receptors located?

A

TR⍺ and TRβ are found in the nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe thyroid hormone action

A 
Functions as a transcription factor
Bind to thyroid responsive element
Higher affinity for T3 and T4
Increases gene transcription 
Can inhibit gene transcription
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the action of thyroid hormones in the anterior pituitary

A

Thyroid gland predominantly secretes T4
Human serum has a high conc of T4 binding proteins this causes high circulating levels of protein bound T4
Only free T3 and T4 are biologically active
T3 and T4 bind to nuclear hormone receptors to alter gene transcription in target cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

List the biological actions of thyroid hormones

A
  1. Control of metabolic rate
  2. Growth
  3. Foetal development
  4. Cardiovascular effects
  5. Musculoskeletal effects
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How are thyroid hormones involved in growth?

What do deficiencies lead to?

A

Affect most bodily functions
Often synergise with other hormones

Deficiencies lead to abnormal growth, development, reproduction, behaviour and metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How are thyroid hormones involved in foetal development?

What happens when there is a low supply of T4?

A

Develop neural and skeletal systems

Loss of T4 supply to the foetus leads to irreversible mental impairment and dwarfism - congenital iodine deficiency syndrome.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the effects of low T4 on a foetus, neonate and child & adolescent?

A

Foetus: miscarriage, still births, congenital abnormalities, perinatal morbidity, mortality and congenital iodine deficiency syndrome

Neonate: goitre hypothyroidism and impaired mental function

Child and adolescent: goiter hypothyroidism, impaired mental function, impaired physical development

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How are thyroid hormones involved in cardiovascular events?

A

T3 increases cardiac contraction and output heart rate, oxygen supply to tissues and CO2 removal from tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the direct effects of thyroid hormones on the heart?

A

Increased myocardial Ca2+ uptake

Increase expression of ⍺-myosin heavy chain and decrease β heavy chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the indirect effects of thyroid hormones on the heart?

A

Increased metabolism - thermogenesis and vasodilation

Increased sensitivity to catecholamamines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How are thyroid hormones involved in musculoskeletal system?

A

T3 has potent stimulatory effects on bone turnover, increasing formation and resorption
T3 increases linear bone growth after birth
T3 increase rate of muscle relaxation
Normal skeletal muscle function requires T3

26
Q

How is calcium involved in bodily functions?

A 
Growth
Maintenance of skeletal system
Neurotransmitter release
Muscle contraction 
Hormone secretion 
Blood clotting
Intracellular Ca2+ signaling
Apoptosis
27
Q

Give examples of calcium rich foods

A

Dairy, kale, spinach, organic tofu, broccoli, almonds and flax/sesame seeds

28
Q

How is calcium homeostasis governed?

A

Careful balancing of absorption, excretion and storage of ions

29
Q

Give 2 examples of main hormones involved in the regulation of calcium homeostasis

A

Calcitonin

Parathyroid hormone

30
Q

Name the cells involved in bone turnover

A

Osteoblasts: synthesise bone tissue
Osteoclasts: resorb bone tissue - they are critical in the maintenance and repair of long bones in the mammalian skeleton

31
Q

Describe primary hyperparathyroidism and treatment

A

Inappropriate excess production and secretion of PTH

Caused by a single benign growth or nodule in one parathyroid gland

Signs and symptoms: increases calcium in blood and urine and calcium deposits in the kidney

Mild disease doesn’t usually need treatment but should be monitors, can offer vitamin D supplements

32
Q

Describe secondary hyperparathyroidism and treatment

A

Long term high PTH levels to attempt to raise blood calcium due to chronic hypocalcaemia

Commonly de to vitamin D deficiency and CKD

Symptoms: muscle aches and weakness

Treat with vitamin D and calcium supplements

33
Q

Give examples of disease states caused by ineffective Ca2+ homeostasis

A 
Primary hyperparathyroidsim
Secondary hyperparathyroidism
Osteoporosis
Rickets 
Calcium stones 
Receptor mutation
34
Q

What is the function of calcitonin?

A

Reduce blood concentration Ca2+

It opposes the effect of PTH: reduces osteoclast activity to reduce bone resorption, allows rapid bone deposition by osteoblasts and to reduce blood Ca2+

35
Q

Describe the parathyroid gland

A

Most people have 4 parathyroid glands located on the posterior surface of the thyroid

Has 2 cell types: chief cells and oxyphil cells
Chief cells are responsible for the production of PTH

36
Q

Describe parathyroid hormone

A

Small helical protein
T half life <20 mins
Function is to increase blood concentration of Ca2+ when it gets too low
Opposes effect of calcitonin

37
Q

Describe the action of parathyroid hormone

A

Low calcium is detected by GPC Ca2+ sensing receptors

Indirectly stimulate oesteoclasts to release more Ca2+ from bone resorption

Increases renal Ca2+ reabsorption, reducing excretion through infiltration

Increases production of vitamin D - increases absorption of Ca2+ from the intestine

38
Q

How is parathyroid hormone regulated?

A

Regulation occurs through negative feedback

  • increase in blood decreases PTH secretion
  • increases bone formation
39
Q

What are the different levels of thyroid disease?

A

Primary thyroid disease: affects production of T3 and T4

Secondary thyroid disease: affects pituitary glands, there are problems with T3 and T4 but also with TSH

Tertiary thyroid disease: knocks out THR

40
Q

What are the causes of primary hypothyroidism?

A

Autoimmune - most common
Result of previous treatment for hyperthyroidism
Iodine imblanace
Congenital hyperthyroidism

41
Q

What are the symptoms of hypothyroidism?

A 
Lethargy
Weakness
Dry scaly skin 
Dislike of cold weather
Depression 
Hair loss
Memory loss
Weight gain 
Constipation 
Gruff voice
42
Q

What would TFTs should in hypothyroidism?

A

Increase in TSH and decrease in free T4

43
Q

What is the initial treatment for hypothyroidism?

A

In adults ≤50 years

  • 50-100µg Levothyroxine OD
  • adjusted by 25-50µg every 3-4 weeks

Adults >50 years and in heart disease

  • 25µg OD
  • adjusted by 25µg every 4 weeks

Congenital hypothyroidism

  • 10-15µg/kg for neonates
  • adjusted by 5µg/kg every 2 weeks

Elderly adults and neonates have similar initial doses

44
Q

What is the maintenance treatment for hypothyroidism?

A

Adults: 100-200µg
Children: 50-200µg

Monitor TSH yearly - should be in the lower half of reference range

45
Q

Can be used as a combination treatment for hypothyroidism?

A

Liothyronine and levothyroxine

46
Q

Give the counselling points for a patient with hypothyroidism

A

Life long treatment
Single daily dose
Don’t take at the same time as calcium/iron preparations
3 strengths of tablet
Need monitoring
Entitled to medical exemption certificate

47
Q

What are the symptoms of hyperthyroidism?

A 
Anxious
Palpitations 
Tremour
Weight loss
Tachycardia 
Goitre
Sleeping 
Diarrhoea
48
Q

What would TFTs should in hyperthyroidism?

A

Reduced TSH and increased T4

49
Q

Which patient groups are thioanamides preferred as treatment for hyperthyroidism?

A 
Children, 
Pregnancy, 
Breast feeding, 
Uncomplicated disease in young adults
Acute phase prior to surgery
50
Q

How do thionamadies work?

A

Interfere with thyroid hormone synthesis by inhibiting thyroperoxidase activity in the follicular lumen

51
Q

Which drug is is first line in hyperthyroidism?

How should it used?

A

Carbimazole
15-40mg OD initially depending on severity
Maintain until TFTs are normal (4-8 weeks)
Maintenance for 12-18 months

52
Q

What is the blocking replacement regimen in hyperthyroidism?

A

Carbimazole 40-60mg for 4 weeks then

Carbimazole 40-60mg + thyroxine 50-100mg

53
Q

Give the counselling points for a patient with hyperthyroidism

A

Carbimazole OD
Tell them duration of treatment and tapering
Short term use of beta blockers
Report signs of agranulocytosis and hepatic dysfunction
Regular medicines review
Management of relapse

54
Q

What is the treatment regime for propylthiouracil?

A

200-400mg daily initial and in divided doses

Reduce to 50-150mg daily maintenance

55
Q

What are the disadvantages of propylthiouracil and carbimazole?

A

They cause drug induced agranulocytosis - bone marrow suppression
White cell count is suppressed which increases risk of infection

56
Q

When would radioactive iodine be used in hyperthyroidism?

A

When patient has failed to respond to drug treatment, relapse after drugs and toxic nodular goitre

57
Q

When would surgery be used in hyperthyroidism?

A

Oesophageal obstruction
Intolerance to drug treatment
Young age

58
Q

What is adjuvant therapy in hyperthyroidism?

A

Beta blockade

Provides rapid relief of symptoms within 4 days

59
Q

Which drugs can induce thyroid disease?

A

Iodine
Aminodarone
Lithium

60
Q

How does iodine induce thyroid disease?

A

Acute overdose: inhibits release of T3/T4
Prolonged overdose: suppressed T3/T4

Iodine deficiency can cause hypothyroidism due to inability to produce T3/T4

61
Q

How does amiodarone induce thyroid disease?

A

Contains organic organic iodine

Hypothyroidism: can occur at any time in treatment, causes inhibition of synthesis and release of T3 and T4. Continue amiodarone and start replacement T4 therapy is necessary

Mild hyperthyroidism: blocks conversion of T4 to T3, this increases TSH and T4. Transient when treatment is started but normalised in 3-4 months

Severe hyperthyroidism: increased production of T4 because of iodine content. Direct thyroiditis - excessive release of T4 into circulation. Withdraw treatment or use carbimazole

62
Q

How does lithium induce thyroid disease?

A

Causes hypothyroidism
Inhibits iodine uptake and prevents T3 and T4 release
Can be transient and subclinical

Hyperthyroidism: rare paradoxical effect

Pharmacy Year 3 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions