Over the last 18 months my TSH level has fallen to 0.03 my T4 is 14
I take 100 of Levothyroxine
My GP wrote to endocrinologist who recommended MRI scan which is this Friday as suspected pituitary problem
Has anyone else had this problem as feeling worried about out come
What's the range for the FT4? Has that risen? Have you been on 100 mcg for the past 18 months? Have you had your FT3 tested? Do you know your levels at the time of diagnosis? I'm afraid we're going to need a lot more detail to be able to help. 
Just testing TSH and FT4 is completely inadequate
What's the range on the FT4?
How do you feel?
For full Thyroid evaluation you need TSH, FT4 and FT3 plus both TPO and TG thyroid antibodies tested. Also extremely important to test vitamin D, folate, ferritin and B12
Low vitamin levels are extremely common, especially if Thyroid antibodies are raised
Low vitamins often lowers TSH
Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and fasting. Do not take Levothyroxine dose in the 24 hours prior to test, delay and take immediately after blood draw. This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, best not mentioned to GP or phlebotomist)
Is this how you do your tests?
Ask GP to test thyroid antibodies and vitamins
Private tests are available. Thousands on here forced to do this as NHS often refuses to test FT3 or antibodies or vitamins
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 special offers, Medichecks usually have offers on Thursdays, Blue Horizon its more random
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 are very common too, especially gluten. So it's important to get TPO and TG thyroid antibodies tested at least once .
Link about thyroid blood tests
thyroiduk.org/tuk/testing/t...
Link about antibodies and Hashimoto's
thyroiduk.org.uk/tuk/about_...
thyroiduk.org.uk/tuk/about_...
Understanding Hashimoto's
hashimotoshealing.com/under...
List of hypothyroid symptoms
Very Low TSH With Low T4
TSH low the rest normal
low TSH Graves’ disease 
Very low TSH and low T4
LOW TSH WITH STABLE T4
