emmteeSeptember 29, 2016 at 11:40 pmPost count: 148
I’ve been on levothyroxine since my thyroidectomy 10 months ago. Over the summer, I became hyperthyroid, and when I saw my endo 7 weeks ago, she lowered my dosage. I was on 175 mcg, and she gave me the option of changing to 150 mcg or just skipping one dose a week. Either way, the weekly dose is 1050, and she said it wouldn’t make a difference. I opted to stay on the same dose and skip a day.
I went in for a blood test this morning. My appointment is next Wednesday, and since I skip Sundays, I figured that testing on Thursday morning would be good. When I woke up and was about to take my levothyroxine, it occurred to me that maybe I should wait until after my blood test to take it. I don’t know why I never thought of this with any of my previous blood tests in the last 10 months. Was I right to wait to take my medication or am I making this more complicated than it needs to be?
BTW – When I see my endo next week, I’m going to ask about switching to the lower dose seven days a week. I thought it would be nice to have a day off, but I end up stressing about it anyway.Liz1967September 30, 2016 at 4:19 amPost count: 305
Your FT4 is highest in the two hours after taking the levothyroxine. FT4 measures how much hormone you have in your blood and since you are not producing it, it reflects how much levothyroxine you are taking. TSH remains stable regardless of eating, activity, etc. It may be affected by time of day, but the studies I have seen are conflicting, some saying lower in middle of night, some morning, some evening, some saying not at all, so i just get blood drawn about same time of day. I pretty much ignore the FT4 as long as it is somewhere within normal range. I would be consistent if you pay attention to FT4.
Levothyroxine has a half life of seven days, which means it is not totally gone for a month at least. Dosing daily or skipping a day will not matter as of the long half life. It may lower FT4 slightly on the skip day or next day as opposed to getting labs within two hours of taking it. It will not affect your TSH, which reflects more of your body’s demand for hormone over time.KimberlyOnline FacilitatorSeptember 30, 2016 at 5:30 pmPost count: 4274
Hello – My doc always stamps on the lab order “no thyroid meds prior to labs“. However, at a recent event hosted by the American Thyroid Association in Denver, most of the docs there did not feel that it made a significant difference. Our Founder, Nancy, suggests getting labs done at the same time of the day (i.e. always morning or always afternoon).emmteeSeptember 30, 2016 at 5:57 pmPost count: 148
Thanks! So, if I had woken up in the very early morning to use the bathroom and taken it then (as I sometimes do), it would have been okay to get my blood drawn several hours later. I think it’s good that I waited yesterday, though, because I didn’t wake up until 7:30 AM and I arrived at the lab at about 10:00.
I actually had to wait an hour and 40 minutes to have my blood drawn. By the time I got home and was able to take my levothyroxine, it was nearly noon. Then I had to wait an hour to finally eat. Next time, I think I’ll make a point of setting my alarm so I can take it in the middle of the night.
I pretty much ignore my TSH and always go by my T4. In the five years since my diagnosis, I’ve only had one normal TSH, and that was a test taken 11 days after my thyroidectomy and 4 days on levothyroxine. That was my best blood test ever – TSH and T4 right in the middle of the normal range. My next test was 5 weeks later, and my T4 was at the high end of the normal range, but my TSH had dropped low again. In my last two tests, my T4 was a little high, but my TSH was too low for the lab to measure. (They only measure as low as 0.006).
(Edited to add: I wrote this just before I read Kimberly’s post. Since this was a test done to evaluate a dosage change, I’m glad I waited to take my medication. From here on out, I’ll try to test at a consistent time – and also make an appointment at the lab so I don’t have to wait so long!)emmteeOctober 6, 2016 at 8:14 pmPost count: 148
I saw my endo yesterday, and asked her this question. Your answers were right on. My endo told me that there is a little boost of hormone right after you take your levothyroxine, so it’s better to take the medication a little late rather than right before your blood test.
My Free T4 was good – right in the middle of the normal range, and my TSH was improved, but still low.
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