Thyroid Disorders Zobeck Flashcards
What is the purpose of the Thyroid hormone?
To regulate metabolism in every cell
Which thyroid hormone is more potent?
T3
Which thyroid hormone has a shorter half life?
T3
Which thyroid hormone is more protein bounded?
T4
What blocks NIS?
SCN, ClO4, low anions
What blocks TPO?
PTU, MMI, Carbimazole
If there is an excess of T4 and T3 in your body, how will that affect TSH and TRH?
negative feedback. Less TSH and TRH.
What are the proteins that TH bind to?
TBG, Albumin, Transthyretin
Is bound TH or unbound active?
UNbound is active because it is free TH
An increase in TBG …
decrease the free T4
What increases TBG
- Pregnancy
- New born state
- HIV infection
- Hepatitis
- Birth control
- Tamoxifen
- Perphenazine
What decreases TBG
- Steroids
- Glucocorticoids
- Salicylates
- Chronic liver disease
- systemic illness
- Nephrosis
- Phenytoin,
- carbamazepine
What is used to measure hormone levels?
Free T4
What are the symptoms of Hypothyroidism?
- Decrease BP, HR, CO
- Cold intolerance
- Constipation
- Lethargy, tired, depressed , mental fogginess
- dry skin, scaly, brittle nails, dry hair
- weight gain, hyperglycemia, hyperlipidemia, hypertriglyceridemia
- Goiter, myxedema
What are the symptoms of Hyperthyroidism?
- increase HR, BP, A. Fib, Myocardial hypertrophy
- Heat intolerance, flushing and sweating
- Anxiety, insomnia, tremor
- Warm/moist skin, hair loss
- Weight loss
- Osteoporosis
What is the most sensitive lab test for thyroid function?
TSH
What tests do you use to diagnose initial diagnosis
- TSH
2. FT4
What test do you use to test for abnormalities
FT3
What lab test is not useful
TT4
What are the FT4, TSH, T3 values for primary Hypothyroidism?
- FT4, low
- TSH, high
- T3 N/A
What are the FT4, TSH, T3 values for central Hypothyroidism?
- FT4, low
- TSH, low
- T3 N/A
What are the FT4, TSH, T3 values for Thyroid-mediated Hyperthyroidism?
- FT4, High
- TSH, low
- T3 High
What are the FT4, TSH, T3 values for TSH-mediated Hyperthyroidism?
- FT4, High
- TSH, High
- T3 High
What does Radioactive iodine uptake scan measure?
- Iodine utilization
2. Differentiates hyperthyroidism etiology
What does Radioactive iodine uptake NOT measure?
hormone synthesis
What does TSab test for?
Autoimmune disease
Test for thyroid stimulating antibodies. which can act like TSH to make hormones
What is Grave’s Disease?
- High FT4
- Low TSH
- Tsab +
- goiter
Autoimmune disease. Antibodies make a lot of TH.
Hyperthyroidism
What is the first and second line defense for Grave’s Disease?
- Thioamides
- Thyroidectomy
- I radiation
What is a Toxic Thyroid Adenoma?
benign tumor that secretes T3 or T4
What are the treatments for hyperthyroidism?
1. Beta blocker Propranolol 10-40 mg q6h 2. Calcium channel blockers -diltiazem, verapamil 3. MMI, PTU 4. Iodine
How should you adjust the dose of PTU, MMI once euthyroid?
Reduce by 30-75%.
What is the dose of Methimazole?
- Initial dose: 15-60 mg/ TID
2. Maintenance dose: 5-15 mg TID
What hyperthyroid drug is preferred?
MMI because they taste better, have a longer half life and is 10 times more potent than PTU
What hyperthyroid drug is preferred for pregnancy?
PTU
What is the dose of PTU?
- Intial: 100-200mg TID q4-6
2. Maintenance: 50-100mg TID
What are the side effects of PTU and methimazole?
- Liver damage
- Leukopenia
- Rash
What are the Iodine treatments available?
- SSKI
2. Lugol’s solution
Which one of the Iodine solution is more concentrated?
SSKI
50mg/drop TID
What are the side effects of Radioactive I and total thyroidectomy?
Hypothyroidism
If a pregnant women has hyperthyroidism, how often should you monitor her FT4?
Every four weeks
What medication for hyperthyroidism is preferred for a mother that is nursing?
MMI
What is Thyroid Storm?
Hyperthyroidism
What are the treatment for Thyroid Storm?
- MMI 60-80 mg
- PTU 500-100mg, 250mg q4
- propranolol 60-80mg q 4h
- SSKI
- Steroid IV
- hydrocortisone 300mg IV x1, then 100mg IV Q8hrs
What do the laboratory results for hypothyroidism show?
- Low TT4
- Low FT4
- High TSH
- High Cholesterol
- Antibodies if Hoshimoto
What are the treatment for hypothyroidism?
- Levothyroxine (T4)
- Initial: 50-125 mcg/day
then 12.5 to 25mcg/day
When do you want to use Liothyronine sodium (Cytomel) over levothyroxine?
- can’t absorb levothyroxine
- Can’t convert T4 to T3
- quicker onset of action
What is Liotrix?
4:1, Levothyroxine:liothyronine
What is Armour Thyroid
For hypothyriodism Natural unstable allergic potential varaible potency
what happens if you over dose on liothyronine?
You cannot go back to T4
What’s the difference between Liothyronine and levothyrioxine
Quicker onset on action and shorter duration
What should you dose an elderly patient if they are using levothyroxine?
12.5-25 mcg/day
Why do you want to monitor elderly patients who are taking Levothryoxine?
They have a slower CL of T4 so they are at risk for toxicity.
How often should you check TSH after a new treatment therapy?
6-8 weeks
What are should CP for Levothyroxine?
- Monitor TSH
- Monitor closely in elderly
- Separate with food, medications and other drinks
What dose of Levothryoxine should elderly be put on?
25 mcg/day. Can be increased 12.5 to 25 mcg q 6-8 weeks
What dose of Levothyroxine should patients with pre-existing coronary artery disease be put on?
12.5 mcg/day can increase dose 12.5mcg q 6-8 weeks
In pregnancy, while taking Levothyroxine, how much should your dose be increased by?
50% because the fetus needs T4 to develop
What are the concealing points for pregnancy and levothyroxine
- Monitor every 4 weeks FSH, FT4
what is Myxedema Coma?
Coma due to long standing hypothyroidism. Have to give T4 in IV because your body is shut down
