I’m going to do the Advanced Test in the morning. My GP tests only TSH and levothyroxine is slowly increasing which I’m ok about I suppose. However, I want to know more about the vitamin component and T3 and 4.
The Medichecks instructions advise test in the morning but don’t say anything about taking the blood before food or levo, which is advised on here before taking the NHS tests. Any advice please?
Secondly - forgive me if this is a stupid question but I’ve read that biotin supplements skew the results - would this apply to Marmite also by any chance?
Many thanks.
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Calceolaria
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* 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. 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). See
biotin use can result in falsely high levels of T4 and T3 and falsely low levels of TSH
These are patient to patient tips which we don't discuss with phlebotomists or doctors.
If you can't meet all this guidance for your test tomorrow I suggest you delay your test or your results won't be accurate.
Check Royal Mail's website for details of strikes, there are many planned for November in the processing and delivery of post. I would post back using Royal Mail's Special Delivery Guaranteed by 1pm Next Day to have any chance at all of it not being delayed on days delivery is taking place.
Biotin is not listed in the B vitamins contained in Marmite:
Thanks Susie. I think I’ll leave the home test until I can tweak my levo dose over a number of days to bring it closer to a 24 hr spacing. I currently take it at about 6.30 - 7 am. It’ll probably be next Monday before I’m ready.
I think I’ll leave the home test until I can tweak my levo dose over a number of days to bring it closer to a 24 hr spacing. I currently take it at about 6.30 - 7 am.
All you need to do is the day before the test is just delay taking your dose by a couple of hours or so, assuming that you will be doing the test around 8.30-9am-ish. No need to tweak timing over a few days.
I’ve never worried about marmite before the test. I spread it like marmite though, not like chocolate spread, so not massive doses.
(And the story goes that before I could introduce the kids to marmite (I love, hubby hates) my parents took them to a party, they made a beeline for the chocolate spread sandwiches, only to find out they were marmite. Neither of them will go near marmite now.)
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