Take your thyroid meds before of after your Labs?

[Vince]

I've been on Thyroid meds for about 7 years now (I'm still not dialed-in). I've been told not to take my meds before my Labs. So my question is, do you take your thyroid meds before or after your Labs?


How To Get Accurate Lab Tests When Taking Thyroid Medications
The Do's and Don'ts of Thyroid Lab Testing - Dr. Izabella Wentz

 

[Mr. T]

I used the info from that exact post and this one prior to my thyroid tests yesterday.

From reading posts, it sounds like you can note the time(s) of the dosage(s) and time of the test and the doctors at Defy can interpret accordingly.

I take mine 12 hours prior to the test, then take the rest after the test. I'm only speculating, but it seems that consistency with respect to timing should at least yield relative results over time.

 

[OMI100]

FWIW
My DR has me test in the A.M. BEFOR taking the thyroid meds....

 

[jdthoosier]

Do you need to fast before taking the tests?

 

[OMI100]

Do you need to fast before taking the tests?

FWIW
I can only address my situation.
I am on NDT (Natural Desiccated Thyroid... Pig Thyroid)
Directions from my DR are to take my NDT on an empty stomach and not eat any food for an hour.
Having food in the stomach will impact absorption of the NDT.
When I do labs in the A.M. it is basically fasting labs, as I have not eaten anything.
After labs I take my NDT and wait an hour before I eat
Not sure of the protocol for NON NDT meds.

 

[Vince]

Do you need to fast before taking the tests?

I would think it isn't necessary to fast for a thyroid panel. Because I take my thyroid meds after my labs, I fast.

 

[Joey786]

When using 5 mcg t3 my fasting free t3 levels before taking medication were 3.0pg/ml (2.0-4.4 pg/ml). I increased the dose to 10mcg t3 and tested again, fasting, before taking medication. My result was still 3.0pg/ml. I could feel a difference going from 5 to 10 mcg but labs didn’t show a difference. I believe this is because of the short half life of t3. I decided to split my dose of 10 mcg t3, 5 mcg AM 5 mcg PM. I tested free t3 levels fasting, before taking my morning dose. My results was 3.4pg/ml. So there was a difference between 5 and 10 mcg. I mattered if I took the whole 10mcg at once or if I took the t3 twice a day. I believe it’s important to test peak levels of t3 to ensure levels aren’t too high. Testing before taking t3 would also be beneficial to ensure levels aren’t too low. I dont believe fasting is required for thyroid labs if your on thyroid medication.

 

[Vince]

The onset of activity of liothyronine sodium is rapid, occurring within a few hours. Maximum harmacologic response occurs within 2 or 3 days, providing early clinical response. The biological half-life is about 2-½ days. T3 is almost totally absorbed, 95 percent in 4 hours.

https://www.rxlist.com/cytomel-drug.htm

 

[Vince]

The half-life of T4 is 5-7 days; the half-life of T3 is only 1 day. Approximately 99% of the circulating thyroid hormone is bound to plasma protein and is metabolized primarily by the liver. Levels of thyroid hormones in the serum are tightly regulated by the hypothalamic-pituitary-thyroid axis.Oct 12, 2016
Thyroid Hormone Toxicity: Background, Pathophysiology, ...
https://emedicine.medscape.com › article

 

[Vince]

However, a single dose of T3 will last about 24 hours in the body more or less, depending on an individual's metabolism of it (6 hour half life X 4 half life cycles = about 6.25% left in the body after 24 hours).
Half Lives of T3/T4 | Fluoroquinolone Toxicity of ...
fluoroquinolonethyroid.com › book_page

 

[Joey786]

I have seen that information on half lives before. I was trying rationalize why my levels were the same on twice the t3 dose. It could be that 5mcg is such a small dose that my thyroid is still active. When I increased to 10mcg my thyroid down regulated and the extra exogenous t3 made up the difference. I still believe that there is a difference taking t3 once per day compared to twice per day.

 

[Vince]

I have seen that information on half lives before. I was trying rationalize why my levels were the same on twice the t3 dose. It could be that 5mcg is such a small dose that my thyroid is still active. When I increased to 10mcg my thyroid down regulated and the extra exogenous t3 made up the difference. I still believe that there is a difference taking t3 once per day compared to twice per day.

Yes I agree with you I believe synthetic T3 should be taken twice a day. The only way you can get good level I would assume. Maybe we need a slow-release T3.

 

[LTChris]

I take about 3 hours before labs

 

[DragonBits]

Yes I agree with you I believe synthetic T3 should be taken twice a day. The only way you can get good level I would assume. Maybe we need a slow-release T3.

If you take T3 with a meal, doesn't that slow absorption? Kind of like creating a slow release?

Has anyone ever experimented with this?

I take NDT twice a day, first time on an empty stomach, second time I don't pay so much attention to eating or not.

 

[Vince]

I take my Synthroid and cytomel in the morning and then in the afternoon the afternoon I take cytomel again. I place it between my lip and gum, I try to slowly absorb it.