Do I need to fast?

[madgewildfire]

I am having the thyroid check plus eleven on Tuesday morning between 9:40 and 10:40 done at home. I know it says that fasting is not necessary but I have seen on here advice to fast before a test so I am wondering if I ought to fast?

[Angel_of_the_North]

I would fast and make sure to leave 24 hours between levo dose and test. It is possible that eating lowers TSH - even if it doesn't, intermittent fasting is a boost for the immune system, so it's win win.

[madgewildfire in reply to Angel_of_the_North]

Thank you, Angel_of_the_North I am not on any treatment as my thyroid seems to yo-yo up and down between borderline hyper and borderline hypo so nothing is ever done about it and I do want it sorted as I feel very unwell. I have been like this for a long time and one doctor told me that it wasn't wise to medicate the elderly. I am just turned 83 so, if one is old, one must just plod on.

[Angel_of_the_North in reply to madgewildfire]

Well, post your results when you get them and someone will comment.

[jimh111]

Fasting makes no difference to thyroid blood test results.

[humanbean in reply to jimh111]

diogenes disagrees. He says that eating reduces TSH. See this thread :

healthunlocked.com/thyroidu...

[jimh111 in reply to humanbean]

I've not seen any research that demonstrates this. There was a study, but they took blood early morning, sent the participants off for breakfast and then took blood again late morning. TSH was lower in the second assay – because it was later in the day, not because of food. A few years later the same team did another study where half the participants had breakfast and half had none. These two groups had a similar fall in TSH, confirming the fall in TSH was due to circadian variation.

If we look at the circadian TSH academic.oup.com/jcem/artic... (fig 1) we do not see a change in TSH at meal times, especially not early evening when most people have their main meal. If I may be allowed to be really naughty I could point to figure 3 in this document frontiersin.org/articles/10... . (Admittedly this is a computer simulation but it wasn't felt necessary to make any corrections for meals).

As far as I know meals do not have a significant effect on TSH, unless I've missed a study that shows they do. On the other hand severe dieting leads to a lower TSH but this is more than just timing, it's due to calorie restriction.

[silverfox7]

I always fast but then I prefer to anyway so that all my tests are done under the same conditions. One day you may be asked to test glucose levels and thyroid fasting would then have to be done.

[madgewildfire in reply to silverfox7]

Thank you all but there appears to be some conflicting opinions re this question. However, I have decided to fast as that seems to be what most do.