Sian, doctors won't tell you about fasting, it is a patient to patient tip, along with the other things I mentioned, to get the highest possible TSH. TSH falls after eating and is also lower later in the day.
Regardless of being borderline, your GP made the decision to start you on Levo. The aim of a treated hypo patient generally is for TSH to be 1 or below and FT4 and FT3 to be in the upper part of their respective reference ranges if that is where you feel well.
Take a look at ThyroidUK's website and Treatment Options here thyroiduk.org.uk/tuk/about_...
It refers to a book written by Dr Toft, leading endocrinologist and past president of the British Thyroid Association and says:
"According to the BMA's booklet, "Understanding Thyroid Disorders", many people do not feel well unless their levels are at the bottom of the TSH range or below and at the top of the FT4 range or a little above."
That book is available from Amazon or pharmacies for about £4.95.
Dr Toft also states in Pulse Onine 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)."
A copy of that article is available by emailing email@example.com
If these are your latest test results
Serum TSH level 4.09 mIU/L [0.3 - 3.94] -Outside reference range
Serum free T4 level 16.2 pmol/L [12.3 - 20.2]
then your GP was correct to raise your dose. However, ifyou have had side effects you might be sensitive to dose increases and need to do it gradually. You could halve the increase, use a pill cutter and take 37.5mcg a day and see how that feels. If all goes well then you could get up to 50mcg eventually.
Are you still on the same brand of Levo or has the brand been changed? Some people do better on one brand than another due to fillers, so a brand change could have caused a problem.
Also worth testing are Vit D, B12, Folate and Ferritin. All need to be optimal (not just in range) for thyroid hormone to work properly.
Nothing particularly stands out as wrong with any of your other tests but you can check them out here, just put the name of the test in the search box labtestsonline.org.uk/under...