I've not contacted this group before. I just got my results back and here they are ;-
My Doctor reduced me from 125 mg to 100mg about 18 months ago and I'm wondering whether my low result is because of this ? I've been feeling rough for months. I'm talking to my GP on Tues and want to ask for my dose to be increased. Any advice ? What can I ask for ?
Many thanks
Written by
Frankham
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If you take your Levo just before the blood test then you are measuring what you have just taken. To get best results and the correct dose you need to have taken your last Levo 24hrs before the blood test. Otherwise you get a false high of FT4 and your doctor will reduce your dose.
Thank you very much ! I don't remember taking my medication before my test though but it is possible , I have been very forgetful of late. I will ask for another test and some more that you mentioned.
To get a measure of your normal circulating hormone and for nothing to interfere in any way with your results, always advised here when having thyroid tests:
* 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.
In fact, 9am is the perfect time, see first graph here, it shows TSH is highest around midnight - 4am (when we can't get a blood draw), then lowers, next high is at 9am then lowers before it starts it's climb again about 9pm:
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.
* Nothing to eat or drink except water before the test - 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. Certain foods 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, split dose and 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 can give false results (most labs use biotin).
These are patient to patient tips which we don't discuss with phlebotomists or doctors.
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