hyperthyroidism

Question 1

How to initially dose Methimazole?

Answer 1

Can initial dose according to FT4 level:
*FT4 1-1.5x ULN: 5-10mg
*FT4 1.5-2x ULN:10-20mg
*FT4 2-3x ULN: 30-40mg

Note that also should take into account patient’s symptoms, gland size, TT3 level (especially TT3

Question 2

How frequently is PTU given?

Answer 2

twice to three times a day

Question 3

What is the typical initial dose of PTU?

Answer 3

50-150mg TID depending on severity of the hyperthyroidism

Question 4

What dose PTU can be used as TFTs and clinical findings return to normal?

Answer 4

50mg 2-3x/day

Question 5

When should FT4 and TT3 be obtained after initial of ATDs (meds)?

Answer 5

2-6 weeks after initiation depending on the severity of thyrotoxiciosis (TSH will lag behind thus not important to monitor in the beginning)

Question 6

When can you start to decrease MMI dose?

Answer 6

Once the patient is euthyroid, the dose of MMI can be decreased by 30-50%

Question 7

When should you retest TFTs after dose of MMI is decreased?

Answer 7

4-6 weeks

Question 8

Timeline of starting MMI to decreasing dose

Answer 8

1. Start MMI
2. Recheck TT3 and FT4 in 2-6 weeks depending on severity of clinical findings and TFTs
3. Increase dose as needed to achieve euthyroid state. Recheck TT3 and FT3 q4-6 weeks after dose change.
4. Once achieve euthyroid state, can start to decrease dose of MMI by 30-50% q4-6 weeks.
5. Once pt is on minimal dose of MMI, TFTs can be repeated q2-3 months.
6. Repeat thyroid antibodies after 12-18 months.
   a)If antibodies are low or negative than can stop MMI.
   b) if antibodies are high
   i. could continue ATD therapy and repeat TRAb after 12-18 months -> reconsider discontinuation of MMI if TRAb levels become negative; pts on long-term MMI should have TFTs q4-6 months and seen for apts q6-10 months
   ii. or could opt for alternate definitive therapy (RAI or surgery)

Question 9

What length of MMI use is considered “long-term MMI”?

Answer 9

> 18 months

Question 10

How frequently to evaluate TFTs if patient is on long-term MMI?

Answer 10

q6 months

Question 11

When is a patient with Graves’ disease considered to be in remission?

Answer 11

Once serum TSH, FT4, and TT3 has been normal for 1 year after discontinuation of ATD therapy

Question 12

What are risk factors for low remission rate of Graves’ disease? (3)

Answer 12

1. Men
2. Smokers (especially men)
3. Pts with large goiters (>/=80g)

Question 13

Relapse rates for pts with persistently elevated TRAb

Answer 13

80-100%

Question 14

Relapse rates for pts with low or undetectable TRAb after MMI treatment

Answer 14

20-30%

Question 15

If TRAb are positive after 12-18 months of therapy what do you do?

Answer 15

A)could continue ATD therapy and repeat TRAb after 12-18 months
B) OR could opt for alternate definitive therapy (RAI or surgery)

Question 16

If pt has persistently high TRAb after 12-18 months of therapy chooses to pursue long-term MMI use, how frequently should TRAb be repeated?

Answer 16

-repeat TRAb q12-18 months

Question 17

Pts on long-term MMI should have TFTs checked how frequently?

Answer 17

Q6-12 months

Question 18

What patients are candidates for long-term MMI if TRAb is persistently elevated after 12-18 months of therapy?

Answer 18

younger pts with mild stable disease on a low dose of MMI

Question 19

If MMI is discontinued for a patient with low or normal TRab after 12-18 months, how frequently should TFTs be checked?

Answer 19

-q2-3 months for the first 6 months
-q4-6 months for the next 6 months
-q6-12 months thereafter
-or sooner if pts develop symptoms of hyperthyroidism

Question 20

What is possible treatment for pt’s with relapse of Graves’ disease?

Answer 20

another course of MMI, RAI or surgery

Question 21

what dosage ratio of MMI to PTU is recommended when switching from one drug to another?

Answer 21

1:20 (MMI:PTU) -> i.e. if pt on 15mg of MMI then they would take 100mg TID of PTU (300mg daily)