how long levothyroxine remains in system

[angelap24]

I have an under active thyroid, reading 3.8 but my doctor will not prescribe medication until that reading is 4.  In the meantime I have put on a stone in weight over the last six  months and feel like a slug, I can not get up in the morning and count the hours until I can get back in to bed.. I have been taking levothyroxine not prescribed for me because it is better than feeling as I do.
Due a blood test soon, how long does it stay in your system? Does anyone know, please?

[gimel]

As a UK member, there are some important things you should become familiar with.  I won't repeat here, but you can get the info from reading the thread under the name of a fellow UK member, LionHeart_62, near the bottom of this page.  

[angelap24]

Thank you very much for your reply. I will see what information I can get from my doctors

[FTB4]

That depends on the actual production or how underproductive your thyroid is, being a supplement Levothyroxine is a T4 Medication, prescribed to replace the hormone your lacking, so every person is different, average time for blood work is 4-6 weeks, in the US it is 6 weeks between labs, they judge that by the time a dosage increase has an effect and shows up in blood tests. Do you have any test results with the ranges they provided, being in the UK, I doubt they did Free T3 and Free T4, but if you have them, please post with ranges for more advise and member comments. Thank You FTB4