# TSH affected by fasting for blood test?



## goatee (Oct 24, 2014)

I've noticed something with my thyroid lab results lately:

Fasting:

TSH - 3.7

T3 - 0.8

T4 - 0.9

Non-Fasting (twice):

TSH - 2.3

T3 - 0.8

T4 - 0.8

My question is: can fasting vs. non-fasting affect my TSH reading that much, or is my thyroid truly sputtering / fluctuating (from 2.3 (non-fasting) to 3.7 (fasting) and then back to 2.3 (non-fasting))? Is the 3.7 reading (fasting) accurate, or could the fasting have spiked it up? Thanks.


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## joplin1975 (Jul 21, 2011)

As I understand it, fasting should not impact your TSH. Whether or not you took your thyroid meds before the blood draw could, feasibly impact the results.


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## Andros (Aug 26, 2009)

http://www.ncbi.nlm.nih.gov/pubmed/15471172

In order to establish long-term continuancey re TSH; one must stick to a rigorous schedule and get labs at the exact same time each and every time bearing in mind that there are exogenous circumstances out of our control. That is why the FREE T3 test is so important.

The above article should confirm.


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## Lovlkn (Dec 20, 2009)

goatee said:


> I've noticed something with my thyroid lab results lately:
> 
> Fasting:
> 
> ...


I would be more concerned with your T-3 and T-4 tests.

Do you take your medication prior to the testing?

You look extremely hypo. Can you please edit your post and confirm the name of the tests run and put the ranges beside the lab.

I fast prior to all lab tests and do not take any replacement medication prior to the lab's - my TSH remains close to normal for me which is 0. I have noticed FT-3 and FT-4 variations if replacement med's were taken prior to lab draw. TSH is useless once replacement medications begin.


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## goatee (Oct 24, 2014)

The ranges for my tests are:

#1

TSH - 2.3 (range 0.4 to 4.0)

Free T4 - 0.9 (range 0.8 to 1.6)

Total T3 - 0.8 (range 0.8 to 1.6)

#2

TSH - 3.7 (range 0.4 to 4.0)

Free T4 - 0.9 (range 0.8 to 1.6)

Total T3 - 0.9 (range 0.8 to 1.6)

#3

TSH - 2.3 (range 0.45 to 4.5)

Free T4 - 1.06 (range 0.82 to 1.77)

Total T3 - 95 (range 71 to 180)

Free T3 - 2.6 (range 2.0 to 4.4)

My symptoms are: extreme hunger no matter what I eat, weight gain (about 20 pounds this past year), rapid heart beat, slightly lighter/shorter periods, exhaustion.

My endo thinks my thyroid is sputtering and fluctuating from 2.3 range to higher (only caught it at 3.7 once). He thinks I should go on 50 mcg of synthroid. He also thinks my blood sugar is fluctuating (causing the rapid heartbeat, otherwise he thinks it's dehydration possibly) and I should take alpha lipoid acid as a supplement to help with that.

I'm feeling physically lousy but am hesitant to start with medicine (being as I'm always extremely medicine sensitive and don't have great reactions). But if I need it, I want to take it. I just don't know. Is it possible my body is swinging back and forth from hypo to hyper? My labs seem fairly hypo (though not terribly), but the rapid heartbeat is also driving me nuts, plus my period is definitely lighter these last few months. Is it possible the synthroid could make my heart beat even more rapid? Also, would the synthroid help my blood sugar fluctuations?

Some more info - I'm 35, otherwise in good health, never had any blood sugar problems until now when my endo says my blood sugar is slightly high for fasting (~100) and that my insulin is high for my glucose levels. I'm all of a sudden also having higher cholesterol (never been a problem for me before) and slightly high blood pressure (always been low before). I also tested positive twice for TPO Hashimoto's antibodies.

I'm very confused as to how to proceed. Any advice would be so much appreciated.


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## joplin1975 (Jul 21, 2011)

You are quite hypo. Did they test your antibodies?


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## Raisenbran (Dec 15, 2014)

I don't know the answer to your question, but your symptoms are interesting to me. I've definitely felt the always hungry sensation for a while now along with your other symptoms. It seems some of them point to hyperthyroid, so I've been confused. I'm curious to see what your doctor says about the 'sputtering' thyroid, since I also see my symptoms worsen, then lessen. I'll be watching this thread, and I wish you good luck!


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## Lovlkn (Dec 20, 2009)

> My endo thinks my thyroid is sputtering and fluctuating from 2.3 range to higher (only caught it at 3.7 once). He thinks I should go on 50 mcg of synthroid.


This is excellent advice to start on 50mcg of Synthroid. It should not be based on TSH though, you need to get in the habit of dosing only by your FT-4 and FT-3 levels which you want to try and get to 3/4 of range. You are quite hypo now.



> My labs seem fairly hypo (though not terribly)


Your frees have been mostly at bottom range - you are very hypo, terribly very hypo.



> Some more info - I'm 35, otherwise in good health, never had any blood sugar problems until now when my endo says my blood sugar is slightly high for fasting (~100) and that my insulin is high for my glucose levels. I'm all of a sudden also having higher cholesterol (never been a problem for me before) and slightly high blood pressure (always been low before). I also tested positive twice for TPO Hashimoto's antibodies.


All due to your being hypo. My cholesterol goes high, as does my glucose, my blood pressure even goes up when on the hypo side. I have had labs for 15 years tracking my thyroid - I speak from experience on this one. TPO antibodies show inflammation and your thyroid is having difficulty producing enough hormone.


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## Andros (Aug 26, 2009)

SUGGESTED TESTS
TPO (antimicrosomal antibodies) TBII (thyrotropin-binding inhibitory immunoglobulin), Thyroglobulin and Thyroglobulin Ab, ANA (antinuclear antibodies), (thyroid hormone panel) TSH, Free T3, Free T4.

You can look this stuff up here and more.........
http://www.labtestsonline.org/
(Copy and paste into your browser)

Trab
http://www.ncbi.nlm.nih.gov/pubmed/17684583
(Copy and paste into your browser)

Blocking TRAbs (also known as Thyrotropin Binding Inhibitory Immunoglobulins (TBII)) competitively block the activity of TSH on the receptor. This can cause hypothyroidism by reducing the thyrotropic effects of TSH. They are found in Hashimoto's thyroiditis and Graves' disease and may be cause of fluctuation of thyroid function in the latter. During treatment of Graves' disease they may also become the predominant antibody, which can cause hypothyroidism.

An ultra-sound would be in order here. Also some "other" antibody tests which I will post above.

Bearing in mind nothing is carved in stone; symptoms can and do cross over. Some hypers gain weight and some hypos lose weight, for example!


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