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Thyroid Cancer, Nodules & Hyperthyroidism (Expert Forum)
Amiodarone based hyperthyroidism
Answered by
Mark Lupo, M.D. - Thyroid Nodules, Thyroid Cancer, hyperthyroidism, hypothyroidism, Thyroid Ultrasound
Thyroid & Endocrine Center of Florida
Sarasota - FL
Questions in the Thyroid forum are answered by Mark Lupo, MD. Topics covered include Goiter, Graves Disease, Hyperthyroid, Parathyroid/Calcium Problems, Thyroid Cancer, Thyroid Nodules/Cysts, Thyroiditis, Thyroid & Pregnancy, Thyroid Stimulating Hormone (TSH), Thyroid Tests, and Thyroid Surgery.
Amiodarone based hyperthyroidism
by mmfd, Sep 25, 2005 12:00AM
Thanks for taking my question. I have multiple cardiac problems and took amiodarone for 2 and a half years, last dose on May 11. I was taken off it for prolonged Q-T syndrome (585). I went into AF with RVR 5 weeks ago. Initially it was thought I had Grave's disease, but the antibodies were negative. I have been on PTU for 5 weeks now and my TSH is still not measurable. I was back in the hospital this past week for recurring AF with RVR. Should I be on steroids also?? My Inderal was increased recently. How long is it going to take to bring my numbers into control? The endocrine guy says it will take several more months. Once I am euthyroid is it necessary to ablate my thyroid? Thanks in advance!
Doctor's Answer
by Mark Lupo, M.D., Sep 25, 2005 12:00AM
, Sep 25, 2005 12:00AM
Amiodarone induced hyperthyroid is complicated. There are two types - 1)iodine overload in which the thyroid is not able to down-regulate thyroid hormone production to compensate (usually in patients with Graves or a toxic nodule) and 2) Destructive Thyroiditis. #1 is more common in the US -- it should be treated with PTU or Tapazole as well as beta-blocker (inderal). The problem is knowing which type it is -- in unstable cardiac patients I have had to treat both at the same time and monitor closely -- that is, use tapazole (or PTU) and steroids. #2 will often get better within 2-3 months on its own and does not respond to antithyroid drugs (as overproduction is not the problem, but destruction of the thyroid -- usually it recovers though). Steroids are helpful in this setting.
Recommendations to discriminate between #1 and #2 - ultrasound with color doppler (increased in #1, minimal doppler flow in #2). Markers of inflammation (eg. IL-6 and ESR) are inc'd in #2. I-123 uptake/scan is only helpful if the uptake is >5% (give or take) as the iodine overload and destruction both cause low uptake but destruction classically causes 0 uptake.
24h urine iodine will tell you how much iodine is still in the system -- remember -- Amio has over a hundred times the RDA of iodine AND takes months to get out of your body -- if urinary iodine is normal - - more likely destructive.
OK - if tapazole/PTU and steroids and beta-blockers not working -- then consider using ioponoic acid (a radiocontrast material) or SSKI or perchlorate -- these are sometimes risky and many endos don't have experience in this regard --- but if they work it may save you from thyroid surgery -- sometimes necessary in severe cases.
Good luck and let me know what happens -- this is a topic I am very interested in....ML
Recommendations to discriminate between #1 and #2 - ultrasound with color doppler (increased in #1, minimal doppler flow in #2). Markers of inflammation (eg. IL-6 and ESR) are inc'd in #2. I-123 uptake/scan is only helpful if the uptake is >5% (give or take) as the iodine overload and destruction both cause low uptake but destruction classically causes 0 uptake.
24h urine iodine will tell you how much iodine is still in the system -- remember -- Amio has over a hundred times the RDA of iodine AND takes months to get out of your body -- if urinary iodine is normal - - more likely destructive.
OK - if tapazole/PTU and steroids and beta-blockers not working -- then consider using ioponoic acid (a radiocontrast material) or SSKI or perchlorate -- these are sometimes risky and many endos don't have experience in this regard --- but if they work it may save you from thyroid surgery -- sometimes necessary in severe cases.
Good luck and let me know what happens -- this is a topic I am very interested in....ML
Member Comments (4)
by mmfd, Sep 25, 2005 12:00AM
I should add that I am a 57 year old female and an RN. My EF is now up to 45% and I have been cleared for a thyroidectomy in case I go into the rapid a fib again. Would you agree that a thyroidectomy would be necessary then? I have been in somewhat a decompensated CHF since the hyperthyroidism started.
by mmfd, Sep 25, 2005 12:00AM
To: Dr. Mark
Hi again. I had an ultrasound right away that showed diffuse enlargement, but I don't believe a doppler was done. I did have a 24 hour urine for iodine done this last admission, but the results weren't back yet. It is complicated by the fact that I had a CAT scan of the chest with contrast done the day I started the PTU. I sure wish the solutions were cut and dried!
by Mark Lupo, M.D., Sep 27, 2005 12:00AM
, Sep 27, 2005 12:00AM
These are tough cases and seldom clear-cut. The 24hU will be tough to interpret -- you certainly have a large iodine load between the amio and the contrast. If not improving - may be worth trying perchlorate or iopanoic acid as a last resort prior to thyroidectomy - often thyroidectomy is the best option for decompensated CHF/a-fib patients.
