Biotin, before blood tests

[airedalelady]

I have a blood test booked for 20th Feb, please can you advise how long before this should I stop taking Biotin, and are there any other "do's or dont's". Am on 75mcgs Levothyroxine daily. Thanks for any advice.

[SeasideSusie Remembering]

airedalelady

It depends on how much biotin you take.

It's high dose biotin, ie >5mg, that affects blood test results and in that case we tend to suggest leaving off for 7 days. That sort of dose is usually found in hair/nail supplements and stand alone biotin supplements.

The amount of biotin in a B Complex is usually something like 400mcg/500mcg and it would be fine to just leave that off for 3 days.

This is what we generally suggest when doing 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:

healthunlocked.com/thyroidu...

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 3-7 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

thyroid.org/patient-thyroid...

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.

[airedalelady in reply to SeasideSusie]

Thankyou for all this helpful information which I have printed off to keep. I am taking a Biotin supplement of 500 ugs (which I think means mcgs), to hopefully help my receding and thinning hair, I also take a B Complex oral spray which contains 50 ugs of biotin, so a daily total of 550 ugs. This seems a very low dosage after reading the amounts mentioned in your reply, do you think I should take more Biotin to battle my hair loss?

[SeasideSusie Remembering in reply to airedalelady]

Sorry but I really know nothing about how effective biotin is for hair loss.

Ferritin needs to be at least 70 ug/L for hair regrowth so have you tested that?

Also hair loss is a symptom of hypothyroidism/undermedication so you need optimal thyroid levels.