EXAM 3 Hypothyroidism Dr. Hess

Question 1

Why is the patient presentation in thyroid diseases so broad?

Answer 1

Because thyroid hormones are involved in the metabolism in many parts of the body

Question 2

Patient presentation in hypothyroidism - Head
EXAM!

Answer 2

-Puffy eyes
-tiredness
-forgetfulness /slow thinking
-moodiness/irritability
-depression
-inability to concentrate
-thinning of hair

Question 3

Patient presentation in hypothyroidism - skin

Answer 3

-loss of body hair
-dry skin
-cold

Question 4

Patient presentation in hypothyroidism - inner body

Answer 4

-elevated cholesterol
-weight gain
-slower heartbeat
-menstrual irregularities/heavy periods
-infertility
-constipation
-muscle weakness, cramps

Question 5

Patient presentation in hypothyroidism - throat

Answer 5

-Swelling (goiter)
-hoarsness/deepening of voice
-dry or sore throat
-difficulty swallowing

Question 6

What is the drug of choice based on the guidelines?

Answer 6

Supplementation of thyroxine
-> synthetic levothyroxine (LT4)

Brands:
-Synthroid
-Levoxyl
-Levothroid
-Unithroid
-Tirosint capsules (gel capsule - better absorption)

Question 7

Why is T4 the drug of choice VS T3?

Answer 7

it most closely mimics normal physiological secretion of T4 -> gets converted to T3 (active form)

Question 8

Practice for changing thyroid drug products

Answer 8

patients should stay on the drug once they are stable

-> different products may NOT be therapeutically equivalent
-> different manufacturer may use different excipients that may influence the absorption -> since it is a narrow therapeutic index drug it can have a significant change in the drug level

-recent studies have shown that switching is just fine (little differences in levels when switching)

Question 9

What is the starting dose for Levothyroxine?

Answer 9

1.6mcg/kg/day
-> use ideal body weight !!! even if obese

Question 10

When should a low dose of Levothyroxine be used?

Answer 10

25 mcg/day -> titrate up to normal blood levels

patients with a history of:

-preexisting heart disease (fe angina, arrhythmias)
-> thyroid increases the HR and may overexert the heart
-osteopenia/osteoporosis (too much LT4 can deplete bone mass)
-elderly

Question 11

Which thyroid drug formulation has its origin in animals (pigs)?

Answer 11

Desiccated thyroids

Thyroid USP
-antigenic risk

Question 12

How should Levothroxine be taken?

Answer 12

-in the morning
-on an empty stomach
-no food or other medications for at least 30 minutes -> to prevent other things to compete with absorption (since narrow therapeutic index)

-can take it at bedtime (no food for 3h before taking it) -> but has to be consistent

Question 13

How should other drugs or foods be spaced from thyroid drugs?

Answer 13

1-2h before

4-6h after
-> otherwise it decreases the absorption of thyroid

Question 14

What is the BBW for thyroid drugs?

Answer 14

Don’t use it for obesity or weight loss management

Question 15

Color and Strengths

Answer 15

Orange = 25mcg
White = 50mcg
Violet = 75mcg
Olive = 88mcg
Yellow = 100mcg

Rose = 112mcg
Brown = 125 mcg
Turquoise = 137mcg
Blue = 150mcg
Lilac = 175 mcg

Pink = 200mcg
Green = 300 mcg

Orangutans Will Vomit On You Right Before They Become Large, Proud Gorillas

Question 16

What is the drug product for synthetic LT3?

Answer 16

Liothyronine (Cytomel)

-Higher incidence of cardiac & thyrotoxicosis adverse effects
-> since we give the active form which directly contribute to the toxicity, rather than T4 which has to be converted first

Question 17

When should combination therapy with LT4 and LT3 be considered?

Answer 17

-the patient has tried LT4 -> the thyroid hormone level is normal but still has symptoms

-rule out other causes before considering combo therapy

Question 18

Which drug product provides the physiologic ratio of the thyroid in its product?

Answer 18

Liotrix (Thyrolar)

T4:T3 -> 4:1

Question 19

How would the TSH and T4 level present in primary Hypothyroidism?

Answer 19

TSH: high

T4: low

Question 20

How would the TSH and T4 level present in secondary Hypothyroidism?

Answer 20

TSH: low

T4: low

Question 21

How would the TSH and T4 level present in secondary Hyperthyroidism?

Answer 21

TSH: low

T4: high

Question 22

When should thyroid levels be checked after starting therapy?

Answer 22

After 6-8 weeks of dose/product change

T4 has a half-life of a week, it takes 5 half-lives to get to steady state -> approx 5 weeks

(T3 has a half-life of 1 day)

Question 23

When should thyroid levels be checked if the patient is stable?

Answer 23

6-12 months

Question 24

Which hormones in the thyroid axis are out of range in the early stage of the disease?

Answer 24

1. TSH
2. T4
3. T3

Question 25

The dose titration is based on the level of which hormone?

Answer 25

TSH
-> TSH levels will tell how severe the hypothyroidism is???

Question 26

What does the term Subclinical hypothyroidism refer to?

Answer 26

-TSH elevated but the free T4 is normal
-NO symptoms

-could be pre-hypothyroidsm where it turns to hypothyroidism with symptoms

-> treatment is controversial -> don’t have to treat, but if we treat we would use the low dose 25 mcg/day

Question 27

How is Hypothyroidism treated in pregnancy?

Answer 27

LT4 is the drug of choice

-increase LT4 replacement dose by 30% when the pregnancy is confirmed, bc thyroid is essential for neural development of the baby

-increase by 50% during the pregnancy

-after delivery go back to the dose they used before

Question 28

How often should TSH levels be monitored in pregnant patients?

Answer 28

every 4 weeks (monthly) after dosage changes