I have ordered The Advanced Thyroid function test from medichecks. It says I need to stop taking B12, two weeks before taking the test and biotin, two days before. I knew about the biotin (I thought that was 8 days prior, not sure where I got that from). I only have a week to stop taking the B12 as a family friend who is visiting is taking the blood draw and she’s only here for the day. How will this affect the result and should I stop taking all my vitamins ie vitamin D before the test. My other question is, I take my Levothyroxine before bed. If I am having my test Saturday morning, when should I take my last dose of Levothyroxine. Your advice on both these queries would be much appreciated.
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Cockerpoo
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What they say about B12 is pretty much nonsense. If you are taking a B12 supplement and want to know your baseline level to see what you are holding on to then you stop B12 for 4-5 months before testing. If you want to see if the amount you are taking is adequate for your needs or to see if you are achieving too high or too low a level then you continue taking it, just take after the test on the day. Stopping it for 2 weeks helps neither of these scenarios.
As for Biotin, it's high dose biotin that needs to be stopped for 7 days, the small amount in a B Complex (eg 300mcg) is fine to stop 3 days before a test, or if you want to be extra cautious then 3-7 days.
As for other supplements, including Vit D, you can continue taking them but take them after the test on the day.
My other question is, I take my Levothyroxine before bed. If I am having my test Saturday morning, when should I take my last dose of Levothyroxine.
There is a problem here. You should not do your test on a Saturday. The sample needs to arrive as quickly as possible, preferably the next day. Medichecks Ts and Cs say:
You must send samples collected in accordance with clauses 8.3 and 8.4 above to the laboratory using the pre-paid envelope provided on the day the sample was taken (or the following day in the case of a home visit which is late in the day) to ensure that it arrives at the laboratory the following day. Failure to do so may lead to deterioration of your sample which could affect the accuracy of your test results. We do not accept responsibility for results that are compromised due to delays in returning samples or where samples are lost in the post. If you are concerned that your usual postal service will not result in next day delivery, we recommend that you return your sample using a guaranteed next-day service. This will be at your cost.
By doing your blood draw on a Saturday, even if you catch Saturday's post it will be hanging around the postal system and the earliest possible time it can be delivered is Monday and you would have to go into the Post Office and request Special Delivery Guaranteed by 1pm Next Day (which should deliver on Monday). All the testing companies that I have seen advise to do the test Monday-Wednesday only if using normal post, or Monday-Thursday if using Guaranteed Next Day delivery. Even then the Guaranteed Next Day delivery can fail (in which case you can claim the fee back), I always use this service and although most do arrive the next day I have had 2 or 3 take 48 hours.
The Royal Mail Tracked 24 envelope enclosed with the kit does not guarantee it will arrive the next working day.
I understand that you may have no alternative, in which case you should understand that there just may be the possibility that the delay might affect the test.
To answer your question about timing of Levo, if you were to do your test on Saturday then you would alter your dose times as follows:
Thursday - delay that night's dose until Friday morning.
Friday morning - take Thursday night's dose.
Saturday morning - do your test, take Friday night's dose after the test.
Hi. Thank you so much for pointing this out. I have spoken to my friend and she is leaving Monday so will take the sample on Monday morning. It didn’t even occur to me. So glad I enquired 👍🏻
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