sudden drop in TSH + switch to Synthroid?

[thegalnextdoor]

I'm a 38 year old female, 5'11", 130 lbs., in very good health. I was diagnosed as hypothyroid several years ago after a TSH test came back at over 28. I was put on 0.05mg of Eltroxin, and my TSH normalized quickly. The following year it was 0.6; the next it was 0.5; but in June 2007 it went back up to 2.58. No big worry...but over the past six months I seemed to develop signs of having too much thyroxine (lost 10 lbs., sleeplessness, anxiety...which I had thought were simply related to an increase in stress in my life).

A couple of weeks ago I went for my annual blood work, and my TSH was only 0.04. My GP has now put me on 0.025mg of Synthroid. I asked whether the unusually low TSH result could be an anomaly, and he said no. I asked what the possible reason could be for a drop like that, and he said, "Sometimes it just happens." I'm not particularly reassured by either answer.

My questions are:

* could stress and weight loss affect TSH? if not, are there other factors that could cause a temporary drop or spike? and have I been switched too soon?

* Eltroxin was working fine (eventually too well, I suppose) and I had no problems on it, but I have heard many stories of people having problems with Synthroid -- is it a mistake to switch brands? I know Eltroxin doesn't make a 0.025mg dose, but I'm very nervous about Synthroid...especially since my doctor has said he'll keep me on it (at 0.025mg and all subsequent increases in dosage) instead of switching me back to Eltroxin, if needed.

* at what point is it reasonable to request a referral to an endocrinologist? I saw one when I was first diagnosed, but didn't need to go back because of the quick normalization. As mentioned, I'm not 100% confident in my family doctor.

Many thanks in advance!

[thegalnextdoor]

Many thanks, Dr. Lupo!

I'm scheduled to return for more blood work in six weeks...though I may return sooner because (after four days on the 25mcg dose) I'm beginning to have dizzy spells and have been feeling somewhat sluggish.

I'm hoping the dizziness is just a temporary side effect resulting from the dosage switch...but if it persists after a couple more days I will go back to the GP.

[thegalnextdoor]

How soon would labs be affected (i.e., would a TSH level be altered) after starting on a new dose of Synthroid?

I ask because I have been on the 25mcg dosage for six days and (after the third day) I've begun having dizzy spells. I've also been feeling very "weepy" and somewhat fatigued...all of which were symptoms I had right before I was diagnosed as hypo four years ago. It feels as though my hypo symptoms are returning.

I'm wondering if a dosage change (up or down) can result in side effects like this and, if so, are they temporary? How long does it take the body to adjust?

And would blood work done less than two weeks after the dosage switch reveal whether the dose is now too low?

Many thanks, once again.

[hypogirl80]

Sounds you are now at the Hyper side. Unless you can see your doctor right away, I think you should stop taking Thyroid for a few days and see if that improve your condition..

[Mark Lupo, M.D.]

This is a good example of why we often recheck an abnormal TSH 5-6 weeks later to confirm that it is not a transient problem.

That being said, would talk to GP about a trial w/o synthroid (b/c 25mcg is quite low and a TSH of 0.04 is also quite low) and a retest in 6 weeks.  If TSH still low, then need evaluation for hyperthyroid etiology which may include an I-123 uptake/scan and/or thyroid antibodies (including TSI to check for Graves)

These things do happen sometimes,  but an endo is probably the best person to sort out why....