Extremely low TSH with normal FT3 and FT4

[binneyc29]

Hi

After being hyper my TSH is now below 0.05 mU/kl (LLow), yet my FT3 is only 5.3 pmol/l and my FT4 is only 13.7 pmol/l; my TRAb is also below 1? I don’t understand how my TSH is so low, yet my thyroid bloods are normal and not high. Does anyone know If this means I have a pituary issue?

Thanks 😊

[tattybogle]

Hi binneyc29 could you give us a bit more information on your history ?

What was the 'operation' you had ?

What was the lump in your neck ? was / is you thyroid enlarged ?

Your profile says you took levo for a while after a birth, but then stopped cos' you felt bad on it.. you profile say's it was prescribed without a blood test ? .. is that right?

Do you mean you were diagnosed with Graves while ft4 / fT3 were in range ? ... or did you have higher T4/T3 results at the time you were told you had graves ?

Your TRab is below 1 ? what was the lab range for that test ? ~ is your result over range ?

Are you taking any levo or carbimazole now ?, or are these you blood results when not taking anything ?

[PurpleNails Administrator]

Please add ranges

FT4 low by most range. FT3 higher but guesswork without range.

How long were you hyper previously? Was is managed? Prolonged hyper can cause TSH to remain low despite hypothyroid levels. TSH is not reliable.

I assume your Graves diagnosis was some time ago? Trab under 1 is likely negative. so that does not confirm Graves - unless was it previously positive? Or TSI ab was previously positive.

Have you had thyroid scan? Ultrasound then if any nodules an uptake scan will show function throughout thyroid.

Nodules can sometimes cause FT3 to rise - followed by FT4. This can occur gradually.

How long were you on Levo replacement? How long were were off levo before test? Or was this all a while ago?

Have TPO & TG antibodies been tested? Thyroiditis can cause transient hyper then ultimately hypothyroid.

Have you have folate, ferritin, vit D and B12 tested recently?

[pennyannie]

Hello Binneyc and welcome to the forum :

Do you have a history of Graves Disease as this can wax and wane throughout one's life.

Graves is an auto immune disease, and there is likely a genetic predisposition with someone in your family maybe a generation away from you with a thyroid health issue, and Graves can be triggered by stress and anxiety.

I have Graves Disease and went through RAI thyroid ablation in 2005.

My TSH is still low suppressed irrespective of what thyroid hormone replacement I take so I must track on my T3 and T4 results and ranges.

The TSH blood test especially when someone has Graves Disease is a very misleading reading and must not be seen in isolation as the TSH can be a false low reading because of Graves antibodies latching onto TSH receptor sites within the body.

I am guessing your T3 and T4 are in range and your TR ab - the thyroid receptor blocking antibody under the range so not positive for Graves at this point time, but please get the ranges so we know what to say rather than guessing - as we could be wrong - who knows ??

Are these results with you having restarted taking T4 - Levothyroxine - as there is room for a dose increase ?

Do you monitor your ferritin, folate, B12 and vitamin D as these need to be maintained at optimal levels to assist your core strength in building strength and stamina.