Thyroid/Parathyroid 1 Flashcards

1
Q

The following are signs of what?

cold intolerance

fatigue

face/eyelid edema

brittle hair/nails

A

Hypothyroidism

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2
Q

The folllowing are signs of what?

heat intolerance

bulging eyes

Inc. HR

weight loss

A

Hyperthyroidism

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3
Q

Which structures release which hormones in relation to the thyroid and parathyroid?

A

hypothalamus –> TRH –> ant pit. –> TSH –> thyroid gland –> T3/T4

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4
Q

Affinity at the receptor for ____ is 10x lower than T3.

A

Affinity at the receptor for T4 is 10x lower than T3.

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5
Q

T/F: Starvation leads to decreased T3/T4 receptors.

A

True

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6
Q

Which drugs cause a decrease in T3/T4?

A

corticosteroids

diclofenac (T3)

Naproxen (T3)

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7
Q

Lab results for Primary hypothyroidism

A

Inc TSH, Dec. T4

This is a thyroid problem

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8
Q

lab results for secondary hypothyroidism

A

dec. free & total T3/T4

cannot trust TSHL it could be nml or decreased

This is a pituitary problem

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9
Q

lab results for autoimmune thyroiditis

A

elevated anti-thyroid peroxidase antibodies

anti-TG antibodies

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10
Q

lab results for subclinical TSH

A

inc. TSH, normal T4

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11
Q

When would you treat subclinical hypothyroidism?

A

if pt has:

  1. iron deficiency anemia
  2. TSH >10
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12
Q

What changes should you make to thyroid medications during pregnancy?

A

Increase thyroid meds dosage by 25-50%

Monitor TSH monthly in 1st trimester

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13
Q

What is the TSH goal in 1st trimester of pregnancy?

A

TSH: 2-2.5

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14
Q

Which drug can increase TSH?

A

amiodarone

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15
Q

What is the half-life of levothyroxine?

A

7 days

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16
Q

When should you recheck labs after giving levothyroxine?

A

4-6 weeks post initial dose or dose change

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17
Q

Levothyroxine mimics which Thyroid hormone?

A

T4

18
Q

What does it mean that the relationship between Levothyroxine (T4) and TSH is not linear?

A

very small changes in T4 concentration can lead to substantial changes in TSH

19
Q

What can impair Levothyroxine (T4) absorption?

How should you take it then?

A

Food can impair absorption

Take in AM 1hr before food

20
Q

Meds that decrease levothyroxine(T4)

A

iron

Ca carbonate

espresso coffee

H2 blockers/PPIs

21
Q

What 2 things could block the conversion of T4 to T3?

A

selenium deficiency

amiodarone

22
Q

Liothyronine (cytomel)

A

synthetic T3

gives you a burst of energy and has rapid onset

23
Q

Dessicated Thyroid Extract

A

natural forms: dessicated pork thyroid gland

NOT RECOMMENDED AS TX

24
Q

Most pts require starting at _____mcg/kg/day of levothyroxine(T4) for full replacement

A

Most pts require starting at 1.6 mcg/kg/day of levothyroxine(T4) for full replacement

25
Q

T/F: dose of Levothyroxine is estimated on ideal Body weight

A

True

26
Q

What Levothyoxine (T4) dosage should you start patients >45y/old w/o CVD on and what should you increase to after 1 month?

A

Initiate with 50mcg QD and increase to 100mcg QD after 1 mo

27
Q

Initial dose of Levothyroxine in older patients

A

25mcg QD: titrate up by 25mcg monthly

28
Q

T/F: Give only 2/3rds of Levothyroxine dose in older patients because they have a greater clearance.

A

False: Give only 2/3rds of Levothyroxine dose in older patients because they have a lesser clearance.

29
Q

T/F: Increase the levothyroxine dose when starting post-menopausal hormone replacement.

A

True

30
Q

Excess doses of Levothyroxine has what 2 effects?

A

Increased serum digoxin levels

decreases sensitivity to warfarin (need to increase warfarin dosage)

31
Q

Excess doses of thyroid hormone cause

A

heart failure

angina pectoris

MI

32
Q

least allergenic levothyroxine dosage?

A

50mcg tablet

33
Q

when do you want to use levothyroxine tx?

A
  1. nodular thyroid dz
  2. diffuse goiter
  3. H/o thyriod irradiation
  4. thyroid CA

Levothyroxine suppresses TSH to keep thyroid from functioning

34
Q

ideal TSH levels of high-risk thyroid CA pts

A

suppress TSH < 0.1

35
Q

ideal TSH levels for low-risk thyroid CA pts

A

suppress TSH to lower limit nml: (0.1-0.5)

36
Q

cardinal signs of hyperthyroidism

A

weight loss and increased appetite

37
Q

antithyroid drugs are 1st line tx in which 3 populations?

A

kids

adolescents

preggos

38
Q

pros of antithyroid drugs

A
  1. noninvasive
  2. reduced cost
  3. decreased risk of permanent hypothyroid
39
Q

cons of antithyroid drugs

A
  1. low cure rate
  2. ADEs
  3. reduced compliance
40
Q

MOA of thiourea drugs

A

serve as preferential iodinating intermediate of thyroid peroxidase–> inhibit coupling of monoiodo tyrosine & diiodotyrosine to form T3 & T4

41
Q
A