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Take thyroid medication day of labs?

I finally met my Endo chronologist. The lab was closed by the time we ended the appointment. I asked her about taking my medication the morning of my blood work she said it did not matter because it takes 5 to 6 days to leave my system anyhow. It was a rather contentious appointment given that she Was over an hour late seeing me as a new patient.  So I need to know should I take my levothyroxine 75 MCG’s the day of my labs or not? After a lot of negotiating she agreed to test my antibodies, free T4 and T3, Cortizol, B 12 and ferritin but will not test me for vitamin D, without a osteoporosis diagnosis.
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It is very disappointing that an Endo displayed such a lack of knowledge about thyroid med.   How long it takes to leave the system is not the issue regarding when to take thyroid med relative to the blood draw.  The issue is how quickly it affects serum levels.   Even the ATA/AACE Guidelines for Hypothyroidism provides a recommendation.    Following is  a link.  

https://www.aace.com/files/hypothyroidism_guidelines.pdf

In the link, on page 999 it states:

"In  monitoring  patients  with  hypothyroidism  on L-thyroxine replacement, blood for assessment of serum free T4 should be collected before dosing because the level will be transiently increased by up to 20% after L-thyroxine administration  (72).  In  one  small  study  of  athyreotic patients, serum total T4 levels increased above baseline by 1 hour and peaked at 2.5 hours, while serum free T4 levels peaked at 3.5 hours and remained higher than baseline for 9 hours (72)"

So, to avoid false high results, which could affect the doctor's decision about your dosage, it is best to delay your thyroid med dose until after the blood draw for tests for FT4 and FT3.  
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Avatar universal
My doctor told me not to.
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1756321 tn?1547095325
I just went to another doctor to have antibodies tested. When the tests came back both high I showed them to the doctor who refused to test these labs. Sour face anyone? lol Last time I saw that Doc.
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1756321 tn?1547095325
Oh I forgot..that sane doctor who refused to test my antibodies did test my vitamin D as I requested. Said no action needed. I requested my lab work to make sure as I trust no doctor. I had vitamin D deficiency. smh
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4 Comments
Can't trust 'em can you?  A Nurse Practitioner I was seeing said my Vitamin D was "good" at 28, but "if I wanted to" it was okay to supplement... seriously!!  I don't see her anymore either.
I stopped being so trusting when my primary doctor for years kept telling me I'm fine your just a "weight worrier" and your swallowing troubles and severe panick attacks were because Im a "weight worrier" to only find out I in fact had thyroid cancer....now that I have no thyroid all my weight gain is because im and "emotional" person and I need diet pills and that my 8 hour a day sleeping habit is not nearly enough because my lack of thyroid has nothing to do with my weight its all my fault.  

I think you need to trust that you doctors have your best interest at heart but I also think you should question everything and research a bit.  I spent years as and ostrich now Im going to spend years running around my health issues like a chicken with its head cut off.

Life is complicated.
Amen sister's! Oh wait sisters is cancelled lol
Don't run around like a chicken with its head cut off - do the research and set out to get what you need.  If your current doctor won't provide it, find one that will.   It mad take several before you find the right doctor, but keep looking.  In my case, I haven't really found the right doctor but I've researched a lot of things and I handle my own supplements, diet, exercise etc and if the doctor don't like it, s/he can get with the program and take care of business.
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