medicheck thyroid test

[Carsey2411]

hi, I know it’s recommended on here to fast but do you need to for the medicheck thyroid home test.

[SeasideSusie Remembering]

"Fasting" is the wrong word. Advice is to do the test no later than 9am, you can have all your normal food the evening before, so that's evening meal and supper (if you normally have supper), just don't have anything but water before the test on the day, so early morning blood draw before breakfast, that's all. This is because some foods and drink may affect TSH and as most doctors adjust dose according to TSH then we don't want to skew that result.

[Carsey2411 in reply to SeasideSusie]

I have to do my test at around 1230. That’s why I ask as I’m starving 🙈

[tattybogle in reply to Carsey2411]

We don't honestly know if eating breakfast will STILL have any noticeable lowering effect on TSH by the time you get to midday . there is no research for that .

The TSH will probably be a bit lower at midday than it would be at eg 9 am (regardless of whether you have breakfast or not) ... so if seeing the highest TSH of the day is what you want to see on a test ..then midday is not the best time to test .. 8/9 am is .

When testing at eg. 9 am , then we DO know that eating breakfast can lower it by as much as 30% in some people... but not everyone... some people don't have much variation in their daily TSH and some have quite a lot.. some people will get lower TSH due to eating breakfast and some won't.

So if you eat now, TSH result may be a bit lower than if you'd stayed hungry till after the test .. or it may make no difference, there is no way to know for sure .

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A recent paper showing that eating breakfast CAN lower TSH quite significantly (when TSH is measured at 9 am):

bmcendocrdisord.biomedcentr...

Effects of calorie intake and sampling time on thyroid stimulating hormone concentration

Aimei Dong, Youyuan Huang, Yucheng Huang & Bing Jia (Published: 01 April 2022 in BMC Endocrine Disorders)

"Discussion

The findings of this study showed that the TSH level was reduced significantly by about 30% after calorie intake in the morning, The components of calories had no significant influence on TSH variation rate when the calories intake was similar. The TSH level was reduced slightly by 5.2% in the subjects after maintaining the fasting state. The rate of TSH reduction was significantly pronounced after calorie intake compare to the fasting state, suggesting that the influence of food on TSH was more evident than the diurnal rhythm of TSH.

The findings of this study showed that the variation of TSH level after calorie intake in the morning might influence the diagnosis of subclinical thyroid dysfunction. Subjects with subclinical hypothyroidism might be underestimated due to the non-fasting state.

Conclusion

In summary, the TSH level was reduced significantly after food intake, compared with that at fasting state in the morning. If the reference range of TSH used in the laboratory was from fasting blood samples, it would be better to evaluate the TSH level in fasting blood obtained in the morning compared with random or postprandial samples."

[Carsey2411]

ok. That’s great. Thank you for the detailed reply