Subclinical Hyperthyroidism or Something Else

[MichelleP_3811]

My TSH generally tests on the low end of the range.  I haven't been out of range but my levels went lower since the last test.  I had a medical procedure and ponder whether or not that is affecting the TSH and that they will go back up given time away from the medical troubles.  That said, my doctor tested my Free T4 since the TSH was so close to the bottom end and the Free T4 actually came back in normal range, actually in the optimal range.  I however do have some minor symptoms related to hyperthyroidism.  The hot flashes and getting hot very easily, a rapid pulse, frequent bowel movements, insomnia, light periods, irritability.  I don't really feel sick persay as I hear most get super sick with hyperthyroidism and my hormone levels are actually good so could there be another reason my TSH is low but my hormones are normal thus causing the symptoms?    

[Barb135]

Thyroid and reproductive hormones must work together in order for us to feel well; it's not unusual for thyroid issues to show up as we age, so I do hope you'll keep on eye on your levels.  Best of luck.

[MichelleP_3811]

Thanks for taking the time to respond.  I actually looked up perimenopause and the symptoms are very similar and I am in my mid 40s.  My periods have gotten lighter over the past 5 or so years and that length of time is when the hot flashes start.  My bowel movements might actually be on the high end of normal though they are overly frequent right before my period but always have been so this well may be an estrogen issue I have been having.  I also had a couple of large fibroids in my history so again this may well be all female related.  Thyroid wasn't even on my radar until the doctor made a comment about my TSH being low but it is still in range so I am sure I am just overly thinking a normal body change associated with age.   I will keep an eye on the symptoms and see if they get worse and I will definitely bring this up with my Gyni on my next check up and see if I can get my estrogen levels checked, I bet they are askew.   Well thanks again for taking the time to respond.  I appreciate you an goolarra explaining it a bit, understanding the thyroid is very confusing.    

[Barb135]

Free T3 is especially important in diagnosing hyperthyroidism, since, as goolarra said, it's the biologically active hormone.  It would be the Free T3 suppressing your TSH and causing symptoms; you really should try to get tested.  

Even if you don't feel "bad", having symptoms indicates that your body is trying to tell you something.

[MichelleP_3811]

My TSH is at .76, range .45 - 4.5 so within range but on the low side and my Free T4 is 1.21, range .8 - 1.8.  I am not on any thyroid meds because I have not been diagnosed with any condition.  There just have been some symptom changes since my last TSH test in the summer which was at .93.  I did not have a FT3 test done.  The doctor did not order it and I thought that was more to diagnose Hypothyroidism.  The only reason I got the T4 test was my heart rate was elevated when I was in the office.  I doubt my doctor would order the FT3 test since I am not really sick like most people with thyroid problems present.  I just noticed new symptoms that I didn't have before and wondered what could cause someone to have fairly low TSH while having normal thyroid levels.  I'm probably just normally low for TSH.  The last 3 years they have always been under 1.  Well I am sure everything is fine.  Like I said, I don't feel outwardly sick just wonder is all and I don't really mind feeling hot because I was always cold before.  : )

[goolarra]

Please post your actual FT4 results with reference ranges.  

In addition to TSH and FT4, your doctor should be testing FT3.  FT3 is the biologically active form of the thyroid hormones and correlates best with symptoms.  There are thyroid conditions that cause FT3 levels to be high, even if FT4 is "optimal".  High FT3 levels could be suppressing your TSH.

Are you on any thyroid meds?