Low FT4 normal TSH

[Miki80]

Can anyone tell me if this is common? And why it would happen?

Thanks

[Clutter]

Miki80,

It will help people answer if you post the TSH and FT4 results and ranges (figures in brackets after results).

[Miki80 in reply to Clutter]

TSH 1.27 (0.35-5.5)

FT4 9.3 (10-19.8)

FT3 4.3 (3.55-5.44)

[Clutter in reply to Miki80]

Miki80,

If you were diagnosed with low-normal TSH and had FT4 at the bottom or below range secondary hypothyroidism would be the most likely reason.

In a previous post you mentioned possible pituitary dysfunction which would cause secondary hypothyroidism. If this is the case TSH should be ignored and treatment should be guided by FT4 and FT3 levels. Your Levothyroxine dose should be increased until FT4 is mid-upper range but FT3 should remain within range.

[Miki80 in reply to Clutter]

Ok but I had a MRI on pituitary last yr- normal.

I don't take Levo I'm on NDT but been on 1 grain a year due to adrenals struggling to raise.

What do I do as 3 Endos don't seem concerned? 😔

[Clutter in reply to Miki80]

Miki80,

I assumed you were taking Levothyroxine. As you are taking NDT it's usual to be guided by the FT3 result as FT4 is often low when taking NDT or T3. I think you may be a little under medicated with TSH 1.27 and FT3 4.3. Perhaps you could increase in 1/4 grain increments as you struggle to increase dose.

[Miki80 in reply to Clutter]

Ok I'll try that thanks, so does this now not point to secondary hypothyroidism or pituitary issue?

Sorry I don't quite understand it all

[Clutter in reply to Miki80]

Miki80,

Not unless TSH and FT4 were both low when you were first diagnosed.

[Miki80 in reply to Clutter]

Lol who knows over 16 years and 3 surgeriesago

[Clutter in reply to Miki80]

Miki80,

If you've had surgery to remove your thyroid you have primary hypothyroidism and FT4 is low because you need a dose increase.

[Miki80 in reply to Clutter]

Oh no sorry I meant doctors surgeries