How long to fast before blood draw

[mountainice]

Hi - I have searched posts but can't seem to find the right one. I have got my kit from Medichecks for thyroid testing and have also found the info on here about blood draw and making sure hands are warm etc. My question is should I fast from after main mail in the evening, around 6.30 or doesn't it matter if I say, eat another snack or drink milk at bedtime - I don't always, just needed to know for the best outcome. Many thanks.

[SeasideSusie Remembering]

mountainice

When doing thyroid tests, we advise:

* Book the first appointment of the morning, or with private tests at home no later than 9am. This is because TSH is highest early morning and lowers throughout the day. If we are looking for a diagnosis of hypothyroidism, or looking for an increase in dose or to avoid a reduction then we need TSH to be as high as possible.

* Fast overnight - have your evening meal/supper as normal the night before but delay breakfast on the day of the test and drink water only until after the blood draw. Eating may lower TSH, caffeine containing drinks affect TSH.

* If taking thyroid hormone replacement, last dose of Levo should be 24 hours before blood draw, if taking NDT or T3 then last dose should be 8-12 hours before blood draw. Adjust timing the day before if necessary. This avoids measuring hormone levels at their peak after ingestion of hormone replacement. Take your thyroid meds after the blood draw. Taking your dose too close to the blood draw will give false high results, leaving any longer gap will give false low results.

* If you take Biotin or a B Complex containing Biotin (B7), leave this off for 7 days before any blood test. This is because if Biotin is used in the testing procedure it will give false results (Medichecks definitely use Biotin, they have confirmed this and the amount of time to leave the supplement off).

These are patient to patient tips which we don't discuss with doctors or phlebotomists.

[mountainice in reply to SeasideSusie]

Thank you. Yes, I have been leaving off supplements as I knew about the Biotin in the B Complex. I am doing a home test, hope I will manage it. My question also was - can I have snacks/milky drinks around 10pm the night before or should it be no food after the evening meal?

[SeasideSusie Remembering in reply to mountainice]

Nothing wrong with a milky drink in the evening but it depends what you mean by "snacks". I don't imagine a biscuit or two would hurt but I wouldn't have more than that.

[mountainice in reply to SeasideSusie]

Ok, we don't usually eat in the evening anyway after our meal, but very occasionally I might eat some cereal before bed! I'll leave that off then. Thanks.