EXAM 3 Hypothyroidism Dr. Hess Flashcards
Why is the patient presentation in thyroid diseases so broad?
Because thyroid hormones are involved in the metabolism in many parts of the body
Patient presentation in hypothyroidism - Head
EXAM!
-Puffy eyes
-tiredness
-forgetfulness /slow thinking
-moodiness/irritability
-depression
-inability to concentrate
-thinning of hair
Patient presentation in hypothyroidism - skin
-loss of body hair
-dry skin
-cold
Patient presentation in hypothyroidism - inner body
-elevated cholesterol
-weight gain
-slower heartbeat
-menstrual irregularities/heavy periods
-infertility
-constipation
-muscle weakness, cramps
Patient presentation in hypothyroidism - throat
-Swelling (goiter)
-hoarsness/deepening of voice
-dry or sore throat
-difficulty swallowing
What is the drug of choice based on the guidelines?
Supplementation of thyroxine
-> synthetic levothyroxine (LT4)
Brands:
-Synthroid
-Levoxyl
-Levothroid
-Unithroid
-Tirosint capsules (gel capsule - better absorption)
Why is T4 the drug of choice VS T3?
it most closely mimics normal physiological secretion of T4 -> gets converted to T3 (active form)
Practice for changing thyroid drug products
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)
What is the starting dose for Levothyroxine?
1.6mcg/kg/day
-> use ideal body weight !!! even if obese
When should a low dose of Levothyroxine be used?
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
Which thyroid drug formulation has its origin in animals (pigs)?
Desiccated thyroids
Thyroid USP
-antigenic risk
How should Levothroxine be taken?
-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
How should other drugs or foods be spaced from thyroid drugs?
1-2h before
4-6h after
-> otherwise it decreases the absorption of thyroid
What is the BBW for thyroid drugs?
Don’t use it for obesity or weight loss management
Color and Strengths
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
What is the drug product for synthetic LT3?
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
When should combination therapy with LT4 and LT3 be considered?
-the patient has tried LT4 -> the thyroid hormone level is normal but still has symptoms
-rule out other causes before considering combo therapy
Which drug product provides the physiologic ratio of the thyroid in its product?
Liotrix (Thyrolar)
T4:T3 -> 4:1
How would the TSH and T4 level present in primary Hypothyroidism?
TSH: high
T4: low
How would the TSH and T4 level present in secondary Hypothyroidism?
TSH: low
T4: low
How would the TSH and T4 level present in secondary Hyperthyroidism?
TSH: low
T4: high
When should thyroid levels be checked after starting therapy?
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)
When should thyroid levels be checked if the patient is stable?
6-12 months
Which hormones in the thyroid axis are out of range in the early stage of the disease?
- TSH
- T4
- T3
The dose titration is based on the level of which hormone?
TSH
-> TSH levels will tell how severe the hypothyroidism is???
What does the term Subclinical hypothyroidism refer to?
-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
How is Hypothyroidism treated in pregnancy?
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
How often should TSH levels be monitored in pregnant patients?
every 4 weeks (monthly) after dosage changes
