Hypothyrodism - test results for TSH level

I had a TSH level test in Feb. 2003 with results showing 0.01 (low).  I was called by the medical staff at my doctors office and informed that my medication did not need to be adjusted.  After much discussion with the staff, they informed me that the results appear low because I am on L-Thyroxine (Synthroid) 100MCG and that causes the results to look low -- that the level was fine.  I had the same TSH test in Feb. 2006 with the same results - 0.01 (low).  This time I was told that my medication would be reduced to 75MCG to bring my TSH level into range.  I am wondering if the reduced Synthroid dosage is correct?  It seems that the dosage would maybe be increased to stimulate the pituitary gland to produce more TSH?  And, at this point, would it be appropriate to request a referral to an Endocronologist?

[Mark Lupo, M.D.]

The TSH comes from the pituitary.  In response to elevated thyroid levels in the body, the pituitary decreases TSH production and vice-versa.  Thus too much synthroid causes a low TSH and a low TSH is associated with increased risk of irregular heartbeat as well as bone loss.  So 0.01 is low and the usual response is a dose decrease (ie to 88mcg)....

[ancientmariner]

Was it 2 different doctors looking at your results? Many doctors don't seem to know/understand/believe that when you are taking oral thyroid meds, your TSH can be suppressed, and is probably not a good test to use to adjust your meds. The way I've heard it said is: A normal thyroid puts out miniscule amounts of thyroid hormone all day long. The pituitary gland checks to see how much thyroid hormone is there, and puts out more TSH if you need more thyroid hormones and less if you don't. TSH comes from the pituitary gland and it tells your thyroid what to do. So now, you're taking oral thyroid replacement - a whole day's worth all at once. Your pituitary senses that, and lowers the TSH, i.e. it's trying to tell your thyroid to stop producing so much.

This certainly makes sense to me - I know it's really a bit more complex than that, but that's the basics. So, it sounds like the first doctor knew this, and the second doctor didn't???

[Dina95]

hi All

My tests showed high TSH =85 and low T4=3 about four months back. after being on Eltroxin 50 raised to 100 for about 10 weeks now, my tests got reversed  into TSH 0.188 and T4 23.However i took my normal dose the day i went for the last test.Is that why my TSH is very low and T4 is high?I also have an annoying pain at my right side of neck especially when i swallow. Should my dose be reduced?! Can hypothyroid turn into hyperthyroid because of high dose.Your comment is really appreciated.

[sharon7]

A related discussion, thyroid was started.

[ElaineZoe]

A related discussion, Insomnia/Hypothyroid medications comparisons was started.