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Thyroid UK
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Can someone help understand Thyroid test results?


I'm new here, 29 yrs old female 5'4 110lbs.

I did my test for thyroid on July 21st just before my menstrual cycle at July 29th.

Fasting, early morning TSH result at 4.58 0.35-5.00 mlU/L

I went back and got detail thyroid work requested on Aug 9th.

No fasting, afternoon TSH result at 3.36 0.35-5.00 mlU/L

T4 free at 15 12-22 pmol/L

Free T3 at 4.8 2.6-5.7 pmol/L

Thyroglobulin AB less than 20 range less than 41 klU/L

Thyroid Peroxidase AB at 18 less than 35 kiU/L

6 Replies


Can you post the lab ref ranges (the figures in brackets after the results)?

The disparity in TSH results is due to testing at different times of day. TSH is always higher early in the morning and before eating and drinking.


Hi Foodie

There are others with much more experience than me who will offer good advice I'm sure, but my thoughts are:-

Not sure why there's a difference in your TSH between the two tests, unless the fasting had an impact. I've never really fasted for thyroid tests, but I don't take my morning medication when I have a morning test as it can show a bit of a spike if your test is not long after you've taken medication.

In general it is thought that TSH is better to be at the lower end of the range, but you'd need to post the range from the lab you had the tests done to determine that. TSH range is usually 0.5 to 4.0 but different labs sometimes use a different range. So I would think it would be better for you if your TSH was quite a bit lower.

What thyroid med are you taking and when do you take it and how long have you been taking it for? And do you have the ranges for your tests? Your Free T3 looks potentially good but again need the range to comment properly.


I pressed the go button about the same time as Clutter :-) apologies for duplicating information.


There's always a difference with the TSH. It is highest earliest a.m. and drops throughout the day. That's why we always recommend the earliest possible blood test and fasting and a gap of 24 hours between thyroid hormones (if prescribed). All of this allows the TSH to be at its highest and prevents GP adjusting the dose unnecessarily.

You can get palpitations etc with low thyroid as heart struggles because it doesn't have sufficient hormones to run our whole metabolism from head to toe. If




Thank you for replies.

Sure, here are the ranges from the lab.

TSH 0.35-5.00 mlU/L

T4 free 12-22 pmol/L

Free T3 4.8 2.6-5.7 pmol/L

Thyroglobulin AB less than 41 klU/L

Thyroid Peroxidase AB less than 35 kiU/L

The problem is that I have symptoms similar to hypothyroidism but my endro doesn't think my thyroid is the issue.


Hi - with a Tsh of 4.58 the issue definitely is your thyroid, as anything over 2ish shows it is struggling. Whether any doctor will treat you or not at that level is down to the individual doctor (I assume you are in US?). Whilst this test doesn't show you positive for auto-immune as antibodies (both lots of AB in results) are below range, these can fluctuate so it isn't conclusive that you are actually negative. The high Tsh is the pituitary gland in the brain shouting at the thyroid to work harder to produce more hormones, predominantly t4, and to convert more of it (mostly done in liver) into the active hormone t3 that drives your entire system from brain to muscles. A good place to learn more is our parent website thyroiduk.org

At your Tsh level you really should merit a trial of treatment, especially if you have multiple symptoms, so could you push for this?

There are somenutrients that are vital for effectiveness of thyroid - vit d, vit b12, folate and ferritin all have to be at fairly high levels - not just in range - to be optimum. Serious deficiencies in these are almost universal with hypo, causing many symptoms of their own as well.

Good luck,



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