Hypothyroidism Flashcards

1
Q

thyroid hormone synthesis steps

A
trapping 
organification 
coupling 
storage 
secretion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is trapping?

A

trapping of iodide, transported by NIS

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

organification

A
  • of iodide into iodine and condensed into tyrosine residues
  • forms MIT or DIT
  • catalyzed by TPO
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

coupling

A

DIT + MIT = T3

DIT + DIT = T4

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

what is the Jod Basedow effect?

A

linear increase in organification / T4 formation with increasing iodide concentration

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

what is the wolff-chaikoff effect?

A

linear decrease in organification / T4 formation with increasing iodide concentration following the jod basedow effect

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

what is the escape phenomenon?

A

linear increase in organification / T4 formation with increasing iodide concentration following the wolff-chaikoff effect?

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

what is the primary binding protein?

A

thyroid binding globulin

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

what factors increase TBG?

A

estrogen (pregnancy, BCP)

congenital

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

what factors decrease TBG?

A

systemic illness

glucocorticoids

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

besides TSH what other hormone can be increased by TRH?

A

prolactin

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

which thyroid test is usually the best test of thyroid function? it is inversely proportional to what function?

A

TSH

inversely proportional to thyroid function

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

hypothryoidism: relationship of TSH and FT4 levels

A

TSH exceeds the reference range before FT4 gets too low

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

hyperthryoidism: relationship of TSH and FT4 levels

A

TSH drops below reference range before FT4 gets too high

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

which thyroid test predicts thyroiditis and hypothyroidism?

A

thyroperoxidase Ab

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

low T3/T4, low TSH

A

secondary / central hypothyroidism

17
Q

low T3/T4, high TSH

A

primary hypothyroidism

18
Q

normal T3/T4, low TSH

A

subclinical hypothyroidism

19
Q

normal T3/T4, high TSH

A

subclinical hypothyroidism

20
Q

high T3/T4, low TSH

A

primary hyperthyroidism

21
Q

high T3/T4, high TSH

A

central hyperthyroidism / resistance

22
Q

secondary / central hypothyroidism

A

low T3/T4, low TSH

23
Q

primary hypothyroidism

A

low T3/T4, high TSH

24
Q

subclinical hypothyroidism

A

normal T3/T4, low TSH

or

normal T3/T4, high TSH

25
primary hyperthyroidism
high T3/T4, low TSH
26
central hyperthyroidism / resistance
high T3/T4, high TSH
27
what is the most common cause of hypothyroidism in iodine-sufficient areas?
hashimoto thyroiditis
28
hashimoto thyroiditis: pathogenesis
autoimmune mediated destruction of thyroid - lymphocytic infiltration
29
what are the clinical features of hashimoto's thyroiditis?
goiter | surface may have a 'bossillated' feel
30
what are the labs associated with hashimoto thyroiditis?
- elevated TSH +/- low T4 - usually TPO antibodies are elevated - classical heterogeneous appearance on US
31
what is the treatment for hypothyroidism?
levothyroxine (T4)
32
what are the contributing factors to hypothyroidism during pregnancy?
- weight gain - increasing TBG levels - increased 5 deiodination
33
what are the clinical features of myxedema coma?
medical emergency consisting of - mental status changes - hypothermia - hypoglycemia - respiratory failure, hypotension, bradycardia
34
during what condition(s) is TSH no longer reliable? what should be used to guide adjustments?
pituitary or hypothalamic insult free T4