thyroid Flashcards

1
Q

Thyroid hormones are derived from ?

A

tyrosine

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

what does the thyroid gland produce

A

thyroid hormones & calcitonin

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

follicle cells produce ?

A

T3 + T4

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

C-cells produce?

A

calcitonin

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

what are the effects of thyroid hormone on the Cardiovascular system

A

↑ CO (↑HR, bp, contractility)
↑ O2 and E consumption
↑ erythropoiesis → ↑ O2 delivery

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

what is the main cause of primary hypothyroidism

A

Lymphocytic thyroiditis
inflammation and damage to thyroid gland –> can’t produce normal amounts of thyroid hormone
↑ circulating anti-thyroglobulin antibodies

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

what is another cause of primary hypothyroidism but very uncommon

A

Congenital hypothyroidism (usually terriers)
Autosomal recessive mutations in the thyroid peroxidase gene

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

what are the causes of Secondary Hypothyroidism

A
  • Lots of other diseases / nutritional status
  • Drug-induced!
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what drugs have the potential to cause Secondary Hypothyroidism

A
  • Trimethoprim / sulfonamides
  • Glucocorticoids
  • Phenobarbital
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

LEVOTHYROXINE is ?

A

T4

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

why is levothyroxine (T4) largely confined to vasculature

A

b/c it mostly binds to plasma proteins

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

what is the main risk w/ giving levothyroxine (T4)

A

causing Iatrogenic hyperthyroidism/thyrotoxicosis (gave too much drug)

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

levothyroxine is contraindicated in patients w/ what illnesses & why

A
  • Thyrotoxicosis - producing too much thyroid hormone to begin with
  • Acute myocardial infarction - T4 has cardiovascular effects (increase CO, increases O2 and E demand)
  • Untreated adrenal insufficiency
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the most common endocrine disorder of cats

A

hyperthyroidism

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

what is the cause of hyperthyroidism in cats

A

adenomatous hyperplasia of the thyroid;
Benign tumor in the thyroid gland that causes uncontrolled production of thyroid hormones

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

what other disease does hyperthyroidism often mask and how

A

Chronic Kidney Disease
b/c hyperthyroidism increases CO which increases perfusion of kidneys & GFR
↑ GFR can mask low GFR of CKD

17
Q

treatment with METHIMAZOLE can often unmask what other illness

A

CKD

18
Q

what drug forms antinuclear antibodies that in can lead to MS like syndrome

A

methimazole

19
Q

why is iodine 131 an irreverisble treatment

A

Radioactive iodine concentrates in thyroid colloid
- causes death of follicle cells (but not C-cells)

20
Q

how does propranolol work to treat hyperthyroidism

A

it promotes the inactivation of T4 by blocking type I+II monodeiodinases (which convert inactive thyroxine T4 into active triiodothyronine T3)

21
Q

how can hyperthyroidism / thyrotoxicosis
cause tachycardia +/- arrhythmia

A

↑ sensitivity to sympathetic stim
↑ CO (↑HR, bp, contractility)

21
Q

how can hyperthyroidism / thyroidotoxicosis result in blindness

A

Hypertension → retinal damage, blindness