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TSH - Erratic Fluctuations?

What would cause TSH levels to fluctuate erratically but yet stay within the range? I'm on Nutri Thyroid and Thyro Complex but since Jan been on a trial of Thyroxine 50mcg. I've had an MRI scan of the pituitary and that appears to be ok, everything was signalling secondary hypothyroidism.

Last year (March) whilst on Nutri Thyroid and Thyro Complex my Free T4 came up slowly to 15 nmol, my TSH was depressed. Yet in July in that heat my Free T4 crashed to 9.3 the lowest I'd known it go. Question is why did it crash?

My Endo thought that I was on Thyroxine when I showed him my results when my Free T4 came upto 15. so he was interested when I told him i was In fact on Nutri Thyroid and Thyro complex.

I am on Sertraline. They've never tested me for antibodies plus I have psoriasis.

Anyone have any ideas?

7 Replies

GSP, SSRIs can increase the metabolism of T4 so you may need an increase in Levothyroxine if you recently started taking Sertraline.

Hashi attacks on your thyroid are the likely reasons for fluctuations in thyroid hormone. 90% of hypothyroidism is caused by autoimmune thyroid disease.


Thanks Clutter, wondering if the Sertraline is causing problems, is a bit like a sticking plaster, I was getting panic attacks for no apparent reason, least little thing would stress me out, would get very anxious. I assume the Sertraline isn't giving me a true reflection on my blood results.

I will ask again for a antibody test, after I was told by my GP that the labs usually request it and it's not something they routinely test for.


GSP, I don't think the Sertraline actually affects your bloods, it didn't mine and I was on 200mcg, it's more that if you were on 50mcg T4 with TSH 1.0 then started Sertraline you may metabolise the 50mcg faster and may need a slight increase in T4 to keep your TSH around 1.0.

1 like

The TSH can vary throughout the day. Excerpt:-

Dr. Lowe:

TSH levels don’t significantly correlate day-to-day[1] or week-to-week.[2] One research group measured the TSH and free T3 and free T4 levels of ten normal young men.[3] When they measured the levels every 30 minutes for 24 hours, they found that the hormone levels were lower during the day and higher at night. During the day, the free T3 was 15% lower, the free T4 was 7% lower, and the TSH was 140% lower. When the researchers measured the hormone levels every five minutes for six to seven hours (7 PM-to-11 PM), the levels varied every thirty minutes. The TSH level varied 13%, the free T3 15%, and the free T4 11%.


I personally think you need an increase in your levo from 50mcg to 75mcg.


Many thanks, my TSH has never gone above 2.5 that I'm aware of range 0.27 to 4.2. My levels don't appear to expressing classic primary hypothyroidism with a really high TSH, could it be tertiary hypothyroidism?


My TSH has been suppressed when on Nutri thyroid and Thyro complex apart from on a couple of occasions. The results seems quite erratic. Above is an old post, bearing in mind my MRI on my pituitary hasn't shown up anything untoward. What would your thoughts be on this?

Thanks again, appreciate any feedback.

I can't help but think whether there is something else underlying.


I would ask for TPO antibody test. My TSH was up and down for 2 years until I felt really unwell. TPO test was very raised


If you are having the test at different times of day you will get fluctuating results. Best to go first thing in the morning as soon as it opens if not before ;)


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