Blood test

[lorrainewilson64]

Doctor sending me for T3 T4 ferritin b12/folate plus my routine diabetes and my cholesterol ....said I don't need to Fast but I've had my levo this morning and breakfast so shud I wait till tomorrow and go b4 medication

[humanbean]

Yes, definitely. Fast overnight (apart from water, which can be drunk freely), don't eat between bedtime and getting your blood taken, don't take any supplements between now and getting your blood taken, don't take any levo between now and getting your blood taken.

In the morning get your blood taken as early in the day as possible.

Take any skipped doses of levo after blood is taken.

Edited : Changed the first paragraph, because I had worded my response very badly and inadvertently suggested that people should starve for nearly a full day. Sorry!

[lorrainewilson64 in reply to humanbean]

Hi thank you will have it done tomorrow morning. .know they said not to Fast as it's not necessary anymore but I'd rather fast

[humanbean in reply to lorrainewilson64]

I would definitely recommend fasting. There are some blood tests for which fasting is required e.g. cholesterol testing and some kinds of blood sugar testing.

Apart from the impact on thyroid tests there are other factors to consider.

Suppose your doctor wanted you to have a cholesterol test and said you should fast for it. Suppose as well that you were also going to have a thyroid function test (TFT) at the same time. If all previous TFTs had been done having eaten breakfast, then how can you compare the results if the conditions had changed?

I arrange all blood tests for first thing in the morning and fast overnight apart from water, unless there is a really, really good reason why I can't do this. It increases the comparability of all my testing.

[Angel_of_the_North in reply to lorrainewilson64]

It's in their interests NOT to have to treat you even if you feel bad, so non-fasting is good for them - lower TSH etc. Not so good for you. The blood sugar ranges are slightly different for fasting and non-fasting, but not much.