11 - Thyroid Disorders

Question 1

What can be concluded from a px w/ normal levels of T4 but high levels of TSH?

Answer 1

They have a thyroid problem b/c the px has to produce more to keep the thyroid levels normal

Question 2

What is the difference between T4 and T3?

Answer 2

T4 is an inactive form that is activated to T3 at the site of action

Question 3

What is the function of TSH? Where is it released from and where does it go?

Answer 3

• Function = stimulate thyroid to release T4

- Released from anterior pituitary and acts on thyroid

Question 4

The majority of _____ in the body goes to the thyroid

Answer 4

Iodine

Question 5

What happens when T4 is metabolized?

Answer 5

• 20% inactivated

- 80% converted to T3

Question 6

What is the relationship between TSH and T4 and T3?

Answer 6

T4 and T3 provide negative feedback on TSH

Question 7

Does T3 or T4 have a longer half life?

Answer 7

T4 (7 days), while T3 (1 day)

Question 8

What are the levels of T4, T3, TSH, and serum thyroglobulin in hypothyroidism?

Answer 8

• T4 = low
• T3 = normal or low
• TSH = high
• Serum thyroglobulin = low

Question 9

What are the levels of T4, T3, TSH, and serum thyroglobulin in hyperthyroidism?

Answer 9

• T4 = high
• T3 = high
• TSH = low
• Serum thyroglobulin = high

Question 10

Do children have higher or lower T3 than adults?

Answer 10

Higher

Question 11

Is hypothyroidism more common in men or women?

Answer 11

Women

Question 12

What is Hashimoto’s thyroiditis?

Answer 12

• Autoimmune disorder

- Antibodies against thyroid peroxidase and/or thyroglobulin gradually destroy thyroid gland follicles

Question 13

What is the presentation of hypothyroidism?

Answer 13

• Slowing of body functions (heart, mental acuity, strength, cold and scaly skin, sparse hair)
• Puffiness (myxadema)
• Droopy eyelids

Question 14

What is the function of thyroid hormone in infants?

Answer 14

Critical for brain development, and important in physical features

Question 15

What are sx of hashimoto’s thyroiditis?

Answer 15

• Slower metabolism
• Reduced CNS activity
• Weight gain
• Fatigue
• Depression
• Constipation
• Memory loss
• Can also cause reactive hyperthyroidism (=> mania, tachycardia, panic attacks)

Question 16

How is hashimoto’s thyroiditis detected?

Answer 16

• Presence of specific antibodies
• Also will see increased TSH and often lymphocyte invasion of thyroid gland
• Enlargement of thyroid (goiter)

Question 17

What effect do thyroid hormones have on catecholamines?

Answer 17

Increase adrenergic receptor sensitivity to catecholamines

Question 18

What effect do hypothyroidism and hyperthyroidism have on ability to get pregnant?

Answer 18

• Hypothyroidism makes it difficult to get pregnant

- Hyperthyroidism increases chances of spontaneous abortion

Question 19

What is the tx for hypothyroidism?

Answer 19

• If due to iodine deficiency, add iodine to diet

- For gland failure, levothyroxine (T4) is tx of choice

Question 20

What happens if a person w/ normal T4 levels is given more T4?

Answer 20

Body only converts T4 to T3 as needed, so it will do no harm

Question 21

How long is it before effects of T4 tx is seen?

Answer 21

2-3 weeks

Question 22

What are sx of hyperthyroidism?

Answer 22

• Exophthalmos (bug eyes)
• Goiter
• Under 40 y/o mainly experience nervous system effects (anxiety, paranoia, mood swings)
• Over 40 y/o mainly experience CV effects

Question 23

What is the prevalence of hyperthyroidism?

Answer 23

• Most common btwn 20-60 y/o

- More prevalent in females

Question 24

What is the most common form of hyperthyroidism?

Answer 24

• Graves’ disease

- Activating antibody to TSH receptor, causes increased T3 and T4

Question 25

What is the tx of choice for hyperthyroidism?

Answer 25

• Radioiodine to destroy portion of thyroid gland

- Normally given 131i

Question 26

What are contraindications for radioiodine?

Answer 26

Pregnancy and children (b/c radioiodine will be taken up into bones)

Question 27

What are some precautions w/ radioiodine?

Answer 27

• Delay in therapeutic response (2-6 months)
• Radiation-induced thyroiditis
• Hypothyroidism (if destroy too much)
• Thyroid cancer

Question 28

What is recommended for px w/ hyperthyroidism who can’t or don’t want radioiodine tx?

Answer 28

Thioamide drugs

• Propylthiouracil (PTU)
• Methimazole
• Carbimazole

Recommended = methimazole once daily and PTU q8h

Question 29

What is the MOA of thioamide drugs?

Answer 29

• Block synthesis of thyroid hormones
• Propylthiouracil inhibits conversion of T4 to T3
• Do not affect uptake of iodine or T4/T3 release

Question 30

Is methimazole or PTU more potent?

Answer 30

Methimazole

Question 31

Antithyroid drug therapy should be adjusted and/or reduced every _____

Answer 31

4-6 weeks

Question 32

What is the tx of choice for hyperthyroidism in pregnancy?

Answer 32

PTU (less placental crossing and no teratogenic reports)

Question 33

What are some side effects of thioamide drugs?

Answer 33

• Fever, rash

- Arthritis-like sx

Question 34

What happens to WBC w/ hyperthyroidism tx? How is the handled?

Answer 34

• WBC counts change w/ thyroid status

- Stop drug therapy at first sign of a sore throat and/or fever and determine WBC status

Question 35

What can kill a px w/ hyperthyroidism? What are the sx?

Answer 35

• Thyroid storm

- Sx = greatly increased BP, SOB, anxiety, sweating, tachycardia, MI

Question 36

What should be given to a px experiencing thyroid storm?

Answer 36

Propranolol