Strange question for u all...

[ThyroidObsessed]

Is ft3 or t3 levels highest at nightime??

I ask as im currently undermedicated and have just started an increase of levo ( not taking t3)... but symptoms seem to ease at night why is this i wonder...

[Clutter]

ThyroidObsessed,

FT3 is highest between 1-3am. See healthunlocked.com/thyroidu...

[jimh111]

I very much doubt it is due to changes in fT3 level. The graphs are a bit misleading as they don't show the origin, in fact fT3 varies from around 5.3 to 5.6. So, the increase from day to night is only about 6% at the most.

[humanbean]

It is quite common for people to mention on this forum that they feel a bit more energetic at night time. I think the cause may often be related to cortisol output.

There is a circadian rhythm to cortisol output :

alpineintegratedmedicineblo...

If the output of cortisol gets "corrupted" and the highs and lows are at the wrong time, or are just too low or too high overall, then people can get bursts of energy at the wrong time e.g. at bedtime or feel completely dead at the wrong time e.g. first thing in the morning. This is common in people with thyroid disease.

This problem can be checked for with a 4-part saliva test privately.

If you were to ever mention cortisol to a doctor they would, at best, do a blood test at 9am. But this is not a good test because it measures total cortisol rather than just the cortisol which the body can make use of. Cortisol in saliva is just the "active" fraction rather than the total cortisol.

[The usual medical terminology for this is that cortisol in saliva is unbound. Blood contains a mixture of bound + unbound cortisol. The unbound level is the one of interest.]

I replied with a list of links to saliva cortisol tests in this thread earlier today :

healthunlocked.com/thyroidu...

[Heloise]

I think HumanBean is correct in pointing out that cortisol is the regulator for some of the symptoms. The adrenals also put out adrenaline and both are to fill in for the lack of thyroid hormone. You need to get your levels of FT4 and FT3 in the upper part of the range the lab gives you.