Fasting before blood tests, vitamins and variou... - Thyroid UK

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Fasting before blood tests, vitamins and various random questions!

Fluffysheep profile image
7 Replies

Sorry if this all comes out as a bit rambling, but have a few different questions to ask!

I've got Hashimotos (the only thing that was right on a recent letter from my one and only Endo appointment, but that's another story!). Was on 50mg of levo until Friday, when the GP upped it to 75mg on the basis of my most recent blood test and me still being massively symptomatic.

Most recent blood test (2 weeks ago) on 50mg levo

TSH 1.39 miu/L (0.27 - 4.2)

T4 13.4 pmol/L (12 - 22)

Nothing else checked, usual NHS rubbish. This was a fasting test done first thing, and I hadn't taken my daily dose of levo, so had been 24 hours since last dose.

I had a blood test done on the 4th October, however it wasn't fasting and I HAD taken my levo (I had no idea they were going to test thyroid levels, it was a pre-op appointment). I'm a bit gutted, as my T3 was checked for this blood test, so really wish I'd know it was going to be done. First question, I know that not fasting and taking your medication before the test means that the TSH result is basically useless (mine was 0.12 for this test!), but does it also effect your T4 and T3 levels, or are they still a reasonable representation of what is going on? My T4 was 20.9 with the same reference range as above, so well up on the test 2 weeks later, which makes me think it was effected after taking my medication. T3 was 5.1, with a reference range of (3.1 - 6.8). The only other time I've had my T3 checked was on a medichecks test prior to being diagnosed, so I wasn't on any medication, but again, I didn't fast (was before I found this site and knew that I should). On that occasion my T3 was 4.7 with the same reference range.

So, if my levo didn't effect T3, and 5.1 is an accurate representation of what it is, does that mean with my most recent T4 being 13.4 that I should be considering trying to source some T3 to try to help with my symptoms, or not? The reason I ask is I am going on a Greek Island cruise soon, I've read that you can buy T3 over the counter in Greece, although can be hard to source, and I'm wondering whether to try when I'm in port. Would love any thoughts on this.

Second question relates to vitamins - I've recently bought the Better You Vitamin D with K3 spray as a test showed I was deficient ( was given a 6 week loading dose then told to sort myself out). I'm currently taking that spray after dinner, whilst having my levo first thing. Just wanted to check that was ok, as I think I read they shouldn't be taken together?

I've also bought the Better You Vitamin B12 spray, although I haven't started that. B12 showed as within range, but it was low, so thought it a good idea to supplement. Does that also need to be taken at a different time to levo? Can it be taken at a similar time to the Vitamin D? Is that spray enough, or is there anything else I should be taking to make it work?

Final question (sorry!) is to do with ferritin and folate. These were tested back in March, were in range but both low. Serum ferritin level was 58ng/mL with a range of 11 - 307, serum folate level was 9.9ng/mL with a range of 3 - 20. Think I've read on here that folate should be at least midway through for thyroid hormone to work, obviously mine isn't. I should point out that I am vegetarian before I'm told to start eating liver etc! Gp not interested, so looking for how best to get these up.

GP basically told me that she is happy to up my levo whilst I am in range for TSH, even if that is right at the bottom, but once it gets there she won't up it any more without the say so of an endo. I saw the endo in September, he seemed ok, but the letter he sent didn't bear much resemblance to what we actually talked about, and he said in that letter that he wanted my TSH to be between 0.5 - 1.5, so I guess I won't get any support from him. He also discharged my back to the GP after the one appointment, so if this recent increase to 75mg of levo takes my TSH under 0.2, I suspect I've got no chance of an increase, which is another reason I've asked about T3 at the beginning of this.

Sorry it's so long, I just needed to get it all down whilst it's all relatively fresh in my head.

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Fluffysheep
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7 Replies
SeasideSusie profile image
SeasideSusieRemembering

I know that not fasting and taking your medication before the test means that the TSH result is basically useless (mine was 0.12 for this test!), but does it also effect your T4

The reason we fast is because eating may lower TSH. It doesn't affect FT4. Coffee also affects TSH.

The reason we leave off Levo for 24 hours is because taking it too close to blood draw gives a false high FT4. It doesn't affect TSH.

If you took your Levo before a test then your FT4 will measure higher than your normal circulating hormone when test is done 24 hours after last dose.

So it looks as though taking your Levo before the test could have lowered your TSH and raised your FT4. Also, TSH is highest early morning and lowers throughout the day, so a 9am test gives the highest TSH and a test between 1-4pm gives the lowest TSH. Graph of daily rhythm of thyroid hormones here:

healthunlocked.com/thyroidu...

So, if my levo didn't effect T3, and 5.1 is an accurate representation of what it is, does that mean with my most recent T4 being 13.4 that I should be considering trying to source some T3 to try to help with my symptoms, or not?

You can't go by an FT3 result from a different test and use it with the TSH and FT4 from another test.

You can only go by all 3 tests being done from the same blood draw.

I wouldn't rely on the results of the tests being done after you'd taken your Levo to make any decisions.

Most recent blood test (2 weeks ago) on 50mg levo

TSH 1.39 miu/L (0.27 - 4.2)

T4 13.4 pmol/L (12 - 22)

These results show that it was right to increase your Levo to 75mcg at that time. You now need to wait 6-8 weeks and retest TSH, FT4 and FT3. See what your levels are then.

Second question relates to vitamins - I've recently bought the Better You Vitamin D with K3 spray as a test showed I was deficient ( was given a 6 week loading dose then told to sort myself out). I'm currently taking that spray after dinner, whilst having my levo first thing. Just wanted to check that was ok, as I think I read they shouldn't be taken together?

As an oral spray is absorbed through the mucous membranes in the oral cavity and bypasses the stomach, and Levo is absorbed through the stomach then the duodenum, jejunum and ileum, the 4 hour gap between Levo and Vit D is irrelevant because of the fact that they are absorbed differently. Even if you were taking D3 softgels or capsules, taking your Levo in the morning and D3 after dinner gives plenty of time.

I've also bought the Better You Vitamin B12 spray, although I haven't started that. B12 showed as within range, but it was low, so thought it a good idea to supplement. Does that also need to be taken at a different time to levo?

Again, as it's a spray then the answer is the same as for the Vit D spray.

However, when taking B12 we need a B Complex to balance all the B vitamins and often there's enough B12 in a good B Complex to raise B12 level, brands recommended here are Thorne Basic B or Igennus Super B. If you don't want to waste your B12 spray you could still use it but you need the B Complex as well. I'd take the B Complex daily and the spray a couple of days a week. A B Complex tablet or capsule needs to be 2 hours away from Levo.

Nothing should be taken at the same time as Levo, there should be 2 hours gap for most other medications and supplements although some need 4 hours. This is so that nothing affect's Levo's absorption.

Final question (sorry!) is to do with ferritin and folate. These were tested back in March, were in range but both low. Serum ferritin level was 58ng/mL with a range of 11 - 307, serum folate level was 9.9ng/mL with a range of 3 - 20. Think I've read on here that folate should be at least midway through for thyroid hormone to work, obviously mine isn't. I should point out that I am vegetarian before I'm told to start eating liver etc! Gp not interested, so looking for how best to get these up.

I was pescatarian but decided my health came first and eating liver was more important to raise my ferritin. Here is a list of iron rich foods:

apjcn.nhri.org.tw/server/in...

The B Complex will improve your folate level.

Fluffysheep profile image
Fluffysheep in reply to SeasideSusie

Thank you for your detailed reply SeasideSusie

SlowDragon profile image
SlowDragonAdministrator

Many people find Levothyroxine brands are not interchangeable.

Once you find a brand that suits you, best to make sure to only get that one at each prescription. Watch out for brand change when dose is increased or at repeat prescription.

Many patients do NOT get on well with Teva brand of Levothyroxine. Though it is the only one for lactose intolerant patients. Teva is the only brand that makes 75mcg tablet.

Fluffysheep profile image
Fluffysheep in reply to SlowDragon

Interesting, thank you. My prescription was given to me as 50mg and 25mg. They are two different brands, and are different to the last lot I had as well (last lot of 50mg was Mercury, I think the first lot of 25mg I was on was Teva). I think one of them of them is Teva this time, can't remember off the top of my head what the other one is but it isn't Mercury.

I have got them from the pharmacy next to the Dr's surgery each time, so I assume they receive different branded tablets. Can I request a specific brand next time when I hand in my prescription, or am I likely to be told sorry, no, you basically get what you're given?

SlowDragon profile image
SlowDragonAdministrator in reply to Fluffysheep

You can get paper prescription so that you can take prescription to different pharmacies if you can't get brand you need at local pharmacy

You can get note added to future prescriptions saying which brand you need (if you know which suits you best)

But pharmacy may still try to supply any brand

Always check bag of medication before leaving pharmacy

Fluffysheep profile image
Fluffysheep in reply to SlowDragon

Thank you.

Problem is, I have no idea what suits me as continually feel crap! If I get to a point I don't I will definitely consider this though.

greygoose profile image
greygoose

First question, I know that not fasting and taking your medication before the test means that the TSH result is basically useless (mine was 0.12 for this test!), but does it also effect your T4 and T3 levels, or are they still a reasonable representation of what is going on?

As far as I know, taking your levo in the 24 hours before test will only affect your FT4. It won't affect your TSH because the TSH doesn't move that fast. :)

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