Lecture 36-Thyroid Flashcards
1
Q
What does TSH stimulate? (3)
A
- TPO synthesis
- activity of the I pump
- movement of T3/T4 across the follicular cell
2
Q
What are the 4 thioureas used to treat hyperthyroid?
A
- thiourea
- thiouracil
- PTU: not usually used due to the severe liver damage it causes
- methimzazole
3
Q
When IS PTU used instead of methimazole?
A
- during 1st trimester of pregnancy (methamizole has teratogenic effects)
- if allergic to methimazole
- during thyroid storm
4
Q
What does methimazole not do?
A
block T4 –> T3 conversion
5
Q
What is nTRE?
A
A response element that TRs bind and even in the presence of hormone represses transcription activation
6
Q
What is a genetic reason that TH may stimulate growth?
A
- The palindrome/direct repeat that TR binds are found in the GH gene
7
Q
Endemic goiter
A
- insufficient dietary I intake
- Insufficient TH made and therefore TSH constitutively released (causing growth)
- common in mountainous areas
- TH tested for in babies because it is EXTREMELY important in growth and brain development
8
Q
Cretinism
A
- low TH at birth due to maternal iodine deficiency: VERY hypothyroid
- short
- large stomach
- preventable if treated at birth
- poor muscle coordination, muscle weakness
- mental retardation
9
Q
Congential Hypothyroidism
A
- insufficient TH due to malfunctioning thyroid
- cretinism prevented by TH treatment at birth
10
Q
Graves disease
A
- activating antibody to TSH receptor (TSI)
- constitutively active TSH receptor, unregulated production of TH
- proptosis due to inflammation behind the eye
- diffuse goiter
- most common form of hyperthyroid
- 70% have Hashimoto’s as well
- treated with I131, PTU or surgery
11
Q
Symptoms of hyperthyroidism (4)
A
- heat intolerance
- tremor
- weight loss
- proptosis
12
Q
Symptoms of hypothyroidism (3)
A
- cold clammy skin
- cold intolerance
- weight gain
13
Q
Hashimoto’s Thyroditis
A
- abs made against Tgb and TPO
- can cause a transient initial increase in thyroid hormone due to TH release from Tgb but ultimately leads to hypothyroid
- people with Hashimoto’s and Graves have destruction and production at the same time but the symptoms depend on which one predominates
14
Q
Why do some people get thryroid storm during surgery? What happens to those with Hashimoto’s?
A
- When doing surgery in and around the neck you may get partial breakdown of the thyroid and follicle rupture. This releases a large amount of TH which significantly increases HR
- Large bolus of I is given to transiently block the effects (it inhibits TH synthesis)
- If someone with Hashimoto’s is given the I this can cause long term blockage of TH production resulting in a goiter and hypothyroidism
- to treat they are given a large bolus of TH that should produce a long term effect
15
Q
What affect does Li on the thyroid?
A
It prevents TH release
