Blood Test

[DEN53]

I am going for my blood test this afternoon at 4 ish but someone said it should be done first thing in the morning. I have never done this

[Animal7]

Hi, yes I need advice on this too! I have my first review after being diagnosed. the only appointment available for a blood test was at 5pm. The receptionist wasn't very helpful. Should I take my Levothyroxine that day or miss the dose - 100mcg? Thanks

[DEN53 in reply to Animal7]

There seems to be different views on this, Animal. I have never been told by Endo Consultant or GP when to have bloods done.

[humanbean]

I'm talking from the point of view of someone who is hypothyroid. Anyone who is hyper may want to do things differently.

Doctors decide on the dose of levothyroxine, or decide whether or not you are hypothyroid, based on the result of a TSH test. It's a terrible way of diagnosing and dosing, but its the way things get done, whether patients like it or not. Most people do not want their thyroid meds reduced and the best way of avoiding it is to get blood drawn when your TSH level is at its highest. There is a circadian rhythm to TSH which you can manipulate to some extent to get the result you want.

Take a look at the graphs on page 2 of this paper :

press.endocrine.org/doi/pdf...

You can see TSH is at its lowest between about midday and 6pm. It is at its highest between about midnight and 4am. Obviously blood tests aren't usually done in the middle of the night, so the best thing we can do to get the highest possible TSH level is get blood drawn by 9am at the very latest.

Another factor to consider is that it is believed that eating will lower TSH. So people who want to get the highest TSH result will get the blood drawn while fasting.

And finally, get blood drawn having not taken meds for 24 hours, and take it instead after blood is drawn.

[Treepie]

Depends what is being tested ,some are fasting tests, cortisol should be tested between 8.00 am and 9am, Thyroid tests as Human Bean States. Some vitamin / mineral tests may not matter. I can make an appointment at the practice which may mean waiting 2 weeks or get an instruction for the hospital which starts taking samples at 7.30 am and go the next day.But there is often 20 plus waiting!