Brief history: 2007 diagnosed overactive; 2011 RAI treatment, so now underactive.
Dosage 150mcg Levo.
Latest bloods:
TSH 3.76 (0.3 - 5)
FT4 21.0 (11 - 20)
FT3 4.8 (3.1 - 6.8)
Does the FT4 mean I'm overmedicated and the TSH undermedicated?
Thanks - Geoff.
When did you take your last dose of levothyroxine prior to the blood being drawn for this test?
Hiya RedApple, I take my levo first thing in the morning and the bloods appt was just before midday.
Geoff.
Aha... this could account for some, if not all, of the apparent discrepancy. When you take levothyroxine (which is T4), it takes a while to get absorbed in the stomach and then into the blood. The FT4 level is typically at it's peak from 2-4 hours after swallowing the pills. Hence, blood level of FT4 will to some extent, directly relate to the timing of the blood draw and taking of the medication.
TSH on the other hand, is not so directly related to the time you take those levo pills. Rather, it tends to stabilise over a period of weeks (assuming a consistent dose of levo during that time). But it does also fluctuate according to time of day, generally being at it's highest in the early hours of the morning, and lower later in the day.
Next time you get tested, on the day, don't take your levothyroxine until after the test. Try to aim for an early morning test appointment, and take that days levo immediately afterwards. This should result in a more accurate picture of how things are when you're at your lowest point (i.e. 24 hours after your last levo dose).
Going back to your question, my interpretation is that as TSH is towards the high end of the range, and FT3 towards the low end of its range, under-medication seems more likely than over.
But the real answer needs to also take into account how you feel. If you feel good, then all is well and there's nothing to be changed. If you don't feel good, then maybe a dose increase would be worth trying. Of course your GP may be reluctant to offer a dose increase if he goes into a panic about the high FT4. But if he goes only by TSH, then he should see that you have plenty of room for manoeuvre.
Wow thanks RedApple - this site is brilliant.
My TSH is coming down but extremely slowly. I will be making an appointment to see my GP to go over these results and it will be interesting to get their interpretation. If I recall rightly my blood results round about September 2012 threw up the same circumstances and the GP was also in two minds whether I was over or under medicated.
At least this time I will have something to add to the discussion.
How am I feeling? The same usual ....... I've completely forgotten what "normal" feels like.
Geoff.
Your GP sounds as if he's not aware of the direct relationship between taking the levo and measuring the FT4 level. No surprise, as most haven't a clue about this. At the moment, I can't bring to mind any medical paper that backs this up, but if I do, i'll post a link for you so that you can go armed with something more than just telling them you heard it on a support group 
Thanks RedApple,
"you can go armed with something more than just telling them you heard it on a support group :)"
Well would you believe my very first Endo consultation went like,
"Yes you've got an overactive thyroid now go home and read about it on the internet"
I kid you not.
So if my GP goes tsk then I can say I'm only doing what I was told to do !
By the way - most if not all of my blood appointments have been between 11 and midday so in future I will wait till after the bloods before I take my Levo.
Geoff.
when i have my blood tests done the nurse always asks me when did i last take my levo i didnt realise you wernt suppose to take it before tests i understand why she asks me know.
Blood results feel over medicated
Confused over FT4 test result
Am I under medicated now 
Symptom of under medicated 
Confused!
