Test time when you dose before bedtime

[Johndillon]

Ive seen alot about testing at 8:30am with a 24 hour gap since last dose. I take my levo at 10:30pm before bedtime (for various reasons) so how would I best test given this?

Also GP tests are random, based on when you get an appointment, how should you interpret results based on this?

Thanks

[SlowDragon Administrator]

Only accept an early morning test appointment ...or test privately

NHS rarely test Ft4 or Ft3

Important to regularly retest vitamin levels too

Remember to stop taking any supplements that contain biotin a week before any blood tests

If you normally take levothyroxine at bedtime/in night ...adjust timings as follows prior to blood test

If testing Monday morning, delay Saturday evening dose levothyroxine until Sunday morning. Delay Sunday evening dose levothyroxine until after blood test on Monday morning. Take Monday evening dose levothyroxine as per normal

[jimh111]

You store around 10 days worth of levo in your blood so each daily dose would only make a 10% difference to the result. Taking the levo the night before is ideal because it will give you the result about half a day after the last tablet, giving a good average fT4 level.

The only problem arises if you take the tablet a few hours before the blood draw, the levo may not have time to bind to the serum transport proteins and give a free T3 figure that is a little high. So, if you take levo in the morning delay the dose until after the blood has been taken. If you take levo at night, or have the blood taken in the afternoon there is no problem.

[SlowDragon Administrator]

Jimh111 has very different view re timings of last dose levothyroxine, than many members

Many of us find timing of last dose has significant difference on Ft4 result

Getting tested early morning important too

researchgate.net/publicatio...

“According to the current TSH reference interval, hypothyroidism was not diagnosed in about 50% of the cases in the afternoon.”

“Further analysis demonstrated inadequate compensation of hypothyroidism, which was defined in 45.5% of the morning samples and in 9% of the afternoon samples”

ncbi.nlm.nih.gov/pubmed/252...

TSH levels showed a statistically significant decline postprandially in comparison to fasting values. This may have clinical implications in the diagnosis and management of hypothyroidism, especially SCH.

[Johndillon in reply to SlowDragon]

Welll I guess this sums up my overall confusion everyone has a different opinion its impossible to know whats right.

Testing in morning isnt an issue as I dont really go by the NHS ones I do my own private testing, it was more about knowing when to dose based on my evening dosing routine and I got an answer here so thanks