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TSH falling while lowering synthroid dose
I am a 37 year old female who was diagnosed with hypothyroidism 8 years ago. I recently have experienced something that has never happened before and am looking for some insight into why this might occur.
Awhile ago I started experiencing symptoms of hyperthyroidism, heart palpitations, etc. My tsh level at the time was .08 (ref range .27-4.20). My synthroid dose was lowered from 137mcg to 125 mcg. Follow up labs 8 weeks later showed a tsh level of .07 and an FT4 level 1.64 (ref range .71-1.85). I was surprised by the results as the palpitations were getting better. Nonetheless, my synthroid dose was lowered again to 112 mcg. Eight weeks later follow up labs showed a tsh level of .04 and an FT4 level of 1.87. All of the labs were performed at the same time of day and by the same lab.
Why would the tsh level continue to drop rather than rise when the synthroid dose is being lowered? Is this something to be concerned about?
Awhile ago I started experiencing symptoms of hyperthyroidism, heart palpitations, etc. My tsh level at the time was .08 (ref range .27-4.20). My synthroid dose was lowered from 137mcg to 125 mcg. Follow up labs 8 weeks later showed a tsh level of .07 and an FT4 level 1.64 (ref range .71-1.85). I was surprised by the results as the palpitations were getting better. Nonetheless, my synthroid dose was lowered again to 112 mcg. Eight weeks later follow up labs showed a tsh level of .04 and an FT4 level of 1.87. All of the labs were performed at the same time of day and by the same lab.
Why would the tsh level continue to drop rather than rise when the synthroid dose is being lowered? Is this something to be concerned about?
Thank you for the responses. I am on regular Synthroid, not generic. I did go off the birth control pill over a year ago. How long does it take for that to show an effect on TSH levels? Also, how important is it to have the TSH level within range. I am currently seeing a nurse practitioner. As long as I am "feeling fine", she doesn't seem concerned about leaving the TSH level at .04.
MEDICAL PROFESSIONAL
Make sure the tablet is not generic -- ie it is Synthroid by Abbott.
Have you stopped any meds that increase thyroid requirements -- ie birth control (or anything with estrogen), zoloft, meds like prilosec, iron, calcium, hi-fiber diet -- to name a few?
The other alternative is that your gland is developing some function -- the most common cause of this is an autonomous nodule -- but this is somewhat unusual.
I usually keep decreasing the dose and re-checking every 8 weeks as your doc is doing then re-evaluate.
Have you stopped any meds that increase thyroid requirements -- ie birth control (or anything with estrogen), zoloft, meds like prilosec, iron, calcium, hi-fiber diet -- to name a few?
The other alternative is that your gland is developing some function -- the most common cause of this is an autonomous nodule -- but this is somewhat unusual.
I usually keep decreasing the dose and re-checking every 8 weeks as your doc is doing then re-evaluate.
Get your adrenal hormones tested. High cortisol can cause T4 to be high, because high cortisol causes a conversion problem from T4 to T3, which in turn would probably explain the falling TSH. You may have developed an adrenal problem along the way. The heart palpitations can be a cortisol problem, too.
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