Low TSH - is that bad?

[saritadelmar]

My Endo continues to "threaten" to reduce the 5 mg T3 I take along with the 75 Levo. The last test of TSH was just in range. I am wondering if my TSH is showing I am on too high a dose, or is it normal to have a low TSH when on T3, even if it is a very small dose. I also have my Vit D result listed and would like a bit of feedback on that. Endo thinks it is okay and warns of not taking too much to bring it higher. I take blood tests as directed continually here on the forum.

Please give your opinions. It is much appreciated. Thank you.

TSH 0.28 mIU/L - 0.40 - 4.50

FT4 1.3 ng/dL - 0.8 - 1.8

FT3 3.0 pg/mL - 2.3 - 4.2

Vit D - 40 ng/mL - 30 - 100

[jimh111]

The problem is your TSH is too low because your pituitary is under performing, not too much thyroid hormone. T3 doesn’t suppress TSH any more than T4 apart from it being more potent. Five mcg L-T3 is nothing, you need at least 10 mcg.

I would supplement vitamin D a little with the winter coming.

[saritadelmar in reply to jimh111]

Thank you for your response. The small dose of T3 made a radical change for the better when I started taking it last November - even on the first day. I wonder whether a higher dose of T3 would lower my TSH even more, and really throw my Endo into a fit.

I should have mentioned that I am supplementing Vit D. I take 4000 IUs daily. So perhaps I need an increase?

Thanks again for your thoughts.

[jimh111 in reply to saritadelmar]

See the comments below re vitamin D.

If you feel a little more L-T3 would help or is needed then try it.

If this causes your endocrinologist to have fits all I can suggest is they get a better understanding of how the thyroid axis works and seek medical attention for their fits.

[saritadelmar in reply to jimh111]

Funny, I will let her know. But when is TSH too low?

[humanbean]

jimh111

The Vitamin D level has been measured in ng/mL rather than nmol/L.

40 ng/mL is equivalent to 100 nmol/L.

Optimal is considered to be 40 - 60 ng/mL or 100 - 150 nmol/L, so although there is nothing to stop someone going a bit higher with a level of 40ng/mL it really doesn't have to go much higher, and they may be fine as they are.

I thought it was unlike you to suggest a higher level of vitamin D when it is already at 100nmol/L, so I'm assuming you didn't notice the units.

[saritadelmar in reply to humanbean]

That makes a lot of sense. I know nothing about the measurements so I am assured now, thanks to you, that I am on a proper dose. Thanks again.

[jimh111 in reply to humanbean]

You’re right I didn’t notice the units. I’m reluctant to assign symptoms to vitamin D deficiency if it is above 20 ng/mL but do accept it is better to aim for a level around 50. This is more important now as there are studies that show a level around 50 or 60 is optimal for a degree of protection from COVID-19.

I need to reread this, I may still be a little mixed up!

[saritadelmar in reply to jimh111]

So taking a bit more can't hurt, in other words. Thanks for this info.

[jimh111 in reply to saritadelmar]

You are close to optimal so allowing for winter maybe just a little bit more but not much.

[saritadelmar in reply to jimh111]

Thanks, good advice. I will check out the link.

[jimh111 in reply to humanbean]

Just to confirm a vitamin D level of around 50 ng/mL is about optimal for fighting SARS-Cov-2 infections as can be seen in this study journals.plos.org/plosone/a... .