Thyroid UK
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Oh no! Ate before blood test

Soo not my proudest moment but I accidentally ate 2 ounces of butter and 1 bag of precooked brown rice around 6:30 and went in for bloodwork around 8:03. I completely forgot not to eat and remembered just as I was in the lab techs office (by this point she was already getting the needles ready to draw blood).

I had a lot of bloodwork done (vitamin d, iron, TSH, ft4, ft3, rt3, ferritin, estradiol, testosterone, progesterone, lipid panel, ect.)

Should I email my doctor? What should I do? My test aren't going to be accurate.

2 Replies


TSH fluctuates throughout the day and night. Blood test are always accurate and are just a snapshot in time. A non-fasting blood test means TSH may be a little lower than it would otherwise be.

Unless you were specifically advised to fast for any of the other blood tests there is no need to worry or contact your GP as they won't be fasting tests.


Petcrazy18 Was that 8.03 in the morning? TSH is always highest early morning and it's useful to get blood drawn then if looking for an increase in thyroid meds, or to avoid a reduction.


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