Can anybody explain to me what exactly this test is?
My GP focuses on TSH, which looks ok in my case (2) but my Free T4 is on the border (mine is 13 and reference is 12 to 23) and I am wondering if this causes some of my symptoms such as night sweats, sore joints, muscle twitches..
Thank you
What is your TSH level?
FT4 should be towards top of range, not right at bottom
See from other posts you have Hashimotos
Are you on strictly gluten free diet? If not ask GP for coeliac blood test
Low vitamins are extremely common too
Ask for vitamin D, folate, ferritin and B12 to be tested
These need to be optimal, not just in range
Post the actual results and ranges and members can advise
50mcg of Levo is only a standard starter dose.
Read as many posts as possible
Learn to take control. Many GP’s under medicate patients, you sound like such a case
My TSH has always been under 2 since I got pregnant (I am 9 months pregnant now). Just got tested for vitamins, VitD is good it looks like I am low on B12 (I am 138, normal range 160-710) and iron has been low since the beginning of pregnancy although I take iron pills. Could these be the reason of muscle twitches baby?
By the way I have been on the standard dose for years-even my TSH went up to 12, they kept me at 50mcg
Thank you for your comments!
Your B12 is very very low and your child could be born with low B12 which would threaten her or his development. I would consider that an emergency if I were your obstetrician. You should be on B12 injections or sublingual high dose B12. Have a look at the films in this article or read it. candobetter.net/node/4463. There are details on risks to children of mothers with low B12. Also, of course, you need supplements for your own health. I cannot believe how cavalier modern doctors are about this. And the addition to cereals of Folic Acid actually creates problems with B12. Good luck.
they don’t even check for b12 as a part of preganncy tests if you don’t ask for it here in the NL. I am giving birth soon so there is nothing i can do to fix my b12 in these last couple of days. I will ask if they can check baby’s levels after she is born of course
T4 is the thyroid storage hormone, that needs to be converted to T3.
Free T4 is the T4 that is available to your body for use - the other type of T4 is called Bound T4 and is tested with a Total T4 test, which tests both Bound T4 and Free T4, but doesn't tell you how much of each.
Low FT4 in itself will not cause symptoms. But, it means that you don't have enough Free T4 to convert to FT3. And, it's low T3 that causes symptoms like you describe. Your FT4 needs to be in the top third of the range for you to have enough.
The NHS, in its doubtful wisdom, does not test for FT3 - and very often not for FT4! - because it's taught its doctors that all they need to diagnose and dose by is the TSH. Doctors have no idea how to interpret an FT3 result! And that's why so many patients are kept sick. 
Private tests are available. Thousands on here forced to do this as NHS often refuses to test FT3 or antibodies
thyroiduk.org.uk/tuk/testin...
Medichecks Thyroid plus ultra vitamin or Blue Horizon Thyroid plus eleven are the most popular choice. DIY finger prick test or option to pay extra for private blood draw. Both companies often have money off offers.
All thyroid tests should ideally be done as early as possible in morning and fasting.
If on Levothyroxine, don't take in the 24 hours prior to test, delay and take straight after. This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, GP will be unaware)
If antibodies are high this is Hashimoto's, (also known by medics here in UK more commonly as autoimmune thyroid disease).
About 90% of all hypothyroidism in Uk is due to Hashimoto's. Low vitamins are especially common with Hashimoto's. Food intolerances common too, especially gluten. So it's important to get antibodies tested.
Low vitamins can cause symptoms too. Low B12 can cause night sweats. Sore joints low vitamin D
Thank you. I know it is not a common symptom but my first sign was night sweats just before I was diagnosed as hypo. After 2 weeks of taking Levo, they disappeared. Every now and then they come back and that's how I know my thyroid isn't doing well. I will try the tests you mentioned, since I have never been tested for FT3 by my GP in the last 5 years
TSH is a hormone produced by the pituitary gland - not the thyroid - which is supposed to rise when your thyroid hormones fall and drop when they rise (but it doesn't work well in everyone and isn't quite as simple as it sounds). GPs can get away with just testing TSH and still following guidelines so they do, but ti doesn't really tell you what your thyroid status is.
The thyroid hormones are Thyroxine, known as T4, and liothyronine, known as T3 (from the number of iodine atoms they contain). A free T4 test shows how much thyroxine is available for the body to use. Although that's better than a TSH test on its own, it STILL doesn't tell you what you need to know as T4 is a storage hormone and doesn't do anything on its own; it has to be converted to T3. so you need all three tests TSH, free T4 and Free t3 done at the same time, early in the morning, fasting (as TSH is affected by time of day and eating). Most healthy people have a TSH around 1.2.
It is possible to have a low or low-ish TSH and still have a thyroid problem if the pituitary gland or hypothalamus aren't working correctly. This a called central hypothyroidism and GPs are NOT equipped to deal with it (or even diagnose it) - needs an endo referral.
If you are on meds, you should not take them for 24 hours before blood test and TSH should be between 0.2 and 1 and free T4 (and free T3) in the top quarter of their ranges.
thank you so much for all this info, it is super helpful. My doctor tells me it is ok to test all thyroid hormones anytime during the day and I can take Levo before. My TSH always comes good (under 2) while my free T4 is always on the lower side. They never ever checked T3.
FT4 should be in top 1/3 of range, NOT at the bottom of range
Dr Toft, past president of the British Thyroid Association and leading endocrinologist, states in Pulse Magazine,
"The appropriate dose of levothyroxine is that which restores euthyroidism and serum TSH to the lower part of the reference range - 0.2-0.5mU/l.
In this case, free thyroxine is likely to be in the upper part of its reference range or even slightly elevated – 18-22pmol/l.
Most patients will feel well in that circumstance. But some need a higher dose of levothyroxine to suppress serum TSH and then the serum-free T4 concentration will be elevated at around 24-28pmol/l.
This 'exogenous subclinical hyperthyroidism' is not dangerous as long as serum T3 is unequivocally normal – that is, serum total around T3 1.7nmol/l (reference range 1.0-2.2nmol/l)."
You can obtain a copy of the articles from Thyroid UK email print it and highlight question 6 to show your doctor please email Dionne at
tukadmin@thyroiduk.org
Official NHS guidelines saying TSH should be between 0.2 and 2.0 when on Levothyroxine
(Many of us need TSH nearer 0.2 than 2.0 to feel well)
See box
Thyroxine replacement in primary hypothyroidism
lactose free t4
Free T4 levels
High free T4
free t4 level 
