Hi I've been on levo for 6 weeks and due to have a blood check on Monday at 9am. When should I take my levo and should I fast?
Best time for blood retest: Hi I've been on levo... - Thyroid UK
Best time for blood retest
Because doctors are so fixed on looking at your TSH reading and want to get it higher then the ideal situation is to give your blood when it's as high as possible in the hope they don't want to lower your medication in an attempt to do this. The level changes throughout the day so the best time to make your appointment is as early as possible. Whether you have eaten or not also changes the value do eating lowers the TSH so do not eat before your test.
So best time is as early as possible and starved.
Also don't take Levo in 24 hours before hand.
If you normally take it at bedtime, or on waking, delay taking it until immediately after blood test.
9am is a good time. The earliest possible is even better. Don't take your Levothyroxine for 24 hours before the test, you can take it as soon as the test is done. It's best not to have breakfast - you can drink water. Of course you can have breakfast after the test.
Apparently your TSH is highest first thing in the morning and drops after a meal and after taking Levothyroxine, and what you want is a nice high TSH so that you don't end up undermedicated.
Don't take your levo within 12 hours of a blood test, it will skew the results.