Timing of taking T4/T3 prior to TSH Lab Work

[bessygo]

I have started taking my T4/T3 at 12:00 am Midnight. If I have fasting TSH lab work done at 7:30 a.m. the following morning, should I still take my Thyroid medication at that time (7 hours prior to testing)? How much are one's TSH/T4/T3 readings effected by NOT taking Thyroid Meds 24 hours prior to testing? Wouldn't I want my readings to reflect what my TSH/T4//T3 are WITH my medication? Why would I want to "alter" my "true readings with medication"? Obviously if the medication wasn't in my system, my numbers would be askew. No? Is this why, perhaps, many drs don't mention fasting, timing of taking meds in relationship to lab testing?

[G2G2]

I use NDT & used to also take T3. My functional medicine doctor said to take 8-10 hours before labs.

[Hidden]

I must admit I question keeping information from our Endos ie: "patient to patient"

myself! I find that deceitful.How can we have an honest relationship with our medical team if we do that ? Would we be happy for them to do that too?

I attend a teaching hospital.Am I helping by deliberately concealing when I last took my medication? My results this visit were the best ever and very good.However,when I said I hadn't taken my meds for 24 hours before the test I was asked "Why not"?

How do I know what percentage to add on ,allowing for my meds,when we are all individuals? If I add 20% to my FT3 now, It goes above range.

Does it now become a guessing game?

I am now being referred to a rheumatologist for my muscular pain which I am happy about .I have spent years blaming it on to being hypothyroid and under medicated.

It's all very confusing.

[SlowDragon Administrator in reply to Hidden]

Thyroid specialist endocrinologists will advise to not take Levothyroxine in 24 hours prior to blood test

And also to not take any T3 in 8-12 hours prior to blood test

Obviously a GP or general endocrinologist will be completely unaware of significance of timings of last dose of Levothyroxine or T3

[SlowDragon Administrator]

You could/should take last dose of T3 8-12 hours prior to blood test. So only need very minor dose time alteration

But ideally would take last Levothyroxine 24 hours prior to blood test

If taking Levothyroxine at bedtime normally, we advise delaying evening dose until morning of day BEFORE blood test. Then taking evening dose from night before straight after blood test

So if testing on a Monday morning. Delay Saturday evening dose until Sunday morning. Delay Sunday evening dose until After Monday blood test

[Hidden in reply to SlowDragon]

Sorry,I'm not meaning to be difficult and yes I do know about time gaps for taking meds before blood tests.Thankfully we are continually reminded here.

Also, when I go for a blood test ,the phlebotomist always asks what meds I am taking and when did I last take them? (NHS Hospital). So I am fully OK with my own situation,but we also see references to info best kept " patient to patient".

I just wondered why? I don't see how that helps anyone?

[SlowDragon Administrator in reply to Hidden]

Because time and time again, if patients request early morning appointment they are told they don't need it, it's irrelevant. Test done in afternoon can be enough of difference in TSH for dose to get reduced

Or if patient asks, GP says they should take Levothyroxine before test. Then FT4 comes back high....dose gets reduced

New NHS England Liothyronine guidelines November 2018 clearly state on pages 8 & 12 that TSH should be between 0.4-1.5 when treated with just Levothyroxine

Note that it says test should be in morning BEFORE taking Levo thyroxine

Also to test vitamin D, folate, B12 and ferritin

sps.nhs.uk/wp-content/uploa...

[SeasideSusie Remembering in reply to Hidden]

but we also see references to info best kept " patient to patient".

This is because most doctors and phlebotomists don't know anything about how levels vary.

Levo and T3 peak in the blood 2-4 hours after ingestion. So taking blood at that point will give a false high because you're measuring the dose just taken. T3 starts to leave the blood after 12 hours, so testing blood after that will give a false low. The blood test can't tell us what's in the cells, only what's in the blood at the time of the blood draw.

According to this article, immediately after taking T3 the TSH starts to fall and can become suppressed, and as most doctors tend to adjust dose by TSH that would probably mean that a doctor would lower the dose.

theinvisiblehypothyroidism....

If we want a reflection of the normal amount of circulating hormone then the advised time gaps will give that.

[bessygo in reply to SeasideSusie]

I take my T3 (just started) and Synthroid at Midnight (12 am). I have incredibly horrible insomnia (parapsychological insomnia, been to sleep labs, etc.etc. take crappy generic 12.5 extended release Ambien and sometimes 1 mg of Ativan when desperate). Since you said T3 peaks 2-4 hours after ingestion, should I be taking these meds in the AM instead? I used to, but because I drink a home made Nespresso with milk and take a calcium chew at that time so I can go on elliptical to get my workout...I opted to take my Thyroid meds at night. However, maybe that is worsening my insomnia? I am beyond frustrated on when to take my thyroid meds. To be honest, for many years, I just took it in the AM and had my coffee and milk and took my supplements since no one told me differently. Now that I am obsessing about it because of messed up circadian rhythms...it seems to be worse. I just started taking soy free phosphatidylserine because my cortisol levels rises at 9:30 pm.....by midnight I am still wide awake even after not sleeping the night before. Then I get horrible carb cravings. I am gluten free since I have Hashimoto (my levels are low....69) so I'm wanting that pasta, those pretzels, etc. I may eat corn chips or have some turkey at 11:30 pm to stop the cravings...Then I may take my Thyroid meds between 2am and 4 am......My symptoms aren't too horrible...hair loss, never fatigued, sluggish...but voice has gotten hoarse and low which is a clear sign my thyroid isn't stable...always wired even on no sleep....I keep reading how everyone reacts differently to T3/T4 meds....I guess there's no answer...but am exhausted experimenting and trying to figure it all out.....thanks to everyones' input....if you were all my doctors, you would have fired me by now!

[SlowDragon Administrator in reply to bessygo]

Have you tried taking T3 as three small doses per day at 8 hour intervals

It's the ONLY way I can tolerate. I take 20mcg per day, 10mcg at 7am, 5mcg at 3pm and 11pm.

But I realise everyone is different

I found by accident (when adjusting last dose of T3 to be 8-12 hours before blood test) that 5mcg T3 before bed dramatically improves my sleep.

[bessygo in reply to SlowDragon]

Thanks so much for your input. I was given a script for T3 5 mcg to be split and to take .25 mcg (which I know is teeny tiny) with my T4 so I take at around midnight. My dr. knows about my anxiety, ADHD , insomnia, etc and was concerned about giving me T3. Now I know why Michael Jackson was taking IV sleep meds....it is horrible to be sleep deprived. My last hope was to adjust my Thyroid meds especially when I was upped to .75 Levo from .50 and my voice got very low and hoarse. I am diagnosing myself since Drs here are busy and I'm a nonentity since I don't have cancer or major issues. Just trying to get through the day ( or night ) at this point. I do use medical cannabis (Glaucoma and cannabis vaped lowers pressures) since I don't want to increase Benzos (I take 1 mg of Ativan at night maybe every 3 nights with an Ambien when I am freaking out about not sleeping). Have tried all the sleep etiquette stuff, lights out, cool room, aromatherapy, etc. Meditation tapes....but when it's dark and quiet my mind goes to bad places...and I know I'm not the only one....a lot of it is from PTSD from caring for dying husband who was a victim of poor medical care and being given RXs from busy drs. I am so aware of this that when a dr. gives me a script, I am already researching it before I agree to take it.....sometimes ignorance is bliss except when it leads to bad side effects from meds....insert sad emoji face RIGHT HERE.

[SeasideSusie Remembering in reply to bessygo]

We have to experiment and find what suits us as an individual. I can take my T3 in one dose along with my Levo, and I don't feel any different from when I was splitting my T3 dose, so for ease I just take it in one dose. Others find they need to split their T3 into 2 or 3 doses.

[Hidden in reply to SeasideSusie]

The Invisblehypothyroidism is an interesting article,so thanks for that.I have also just purchased The Thyroid Patient's Manual by Paul Robinson which will be a good reference book. (recommended by my TUK member friend.)

I don't take my Meds beforehand on the morning of a blood test,but take them when back in the car afterwards.It takes 30mts to drive home from the hospital and then I'm ready to get breakfast and turn on BBC1Breakfast TV and settle down watching the lovely Dan Walker............Oh it's a hard life 😊🌸

[Hidden]

Yes I recommend keeping a record of test results along with meds and changes of dosage.I have kept a typed record since 2012 which was when on only T4 levo and before the addition of T3. It is so helpful when keeping an eye on your thyroid journey.

[SeasideSusie Remembering]

It should be 8-12 hours for NDT because of the T3 it contains. You'll be getting a false low FT3 result if you leave 24 hours and as FT3 is the most important result that's the one to take notice of so needs to be as accurate as possible when taking T3 or NDT.

[SeasideSusie Remembering]

I've not seen any articles that say adding 20% will give an accurate result. It may give some kind of indication but not necessarily accurate. I think a more accurate picture is given when the correct timing is used. The FT4 result is not as important as the FT3 result when on NDT or T3 because taking that will lower FT4 anyway.

[SeasideSusie Remembering]

The previous admin may have done. Did they also link to an article which explained this?

[SeasideSusie Remembering]

I don't know, do you have Hashi's?

[Hidden]

I was only querying "patient to patient "

I'm happy with my medical team.However.....results .....blood test taken at 8.00 am

before taking meds.

TSH 0.06(0.3 - 5.0. FT4 11.5 (7.9 - 16) + 20% 13.8 FT3 5.8 ( 3.8 -6.0 ) +20% = 6.9

Meds. 100/75 mcgs T4. + 10mcgs T3