Possible secondary hypothyroidism (Levels are standard not metric).

I just had my labs checked, my TSH is 0.479 uIU/mL Range - 0.450-5.330 uIU/mL

My T4 is 0.95 ng/dL Range - 0.61-2.00 ng/dL.

With a TSH that low I would expect my T4 to be a bit higher, am I correct in this assumption? Free T3 is on the way.

[Hidden]

I've been on 50 mcg Synthroid for 4-5 weeks.

[SilverAvocado in reply to Hidden]

Derrickbff, 4-5 weeks is a very short time to then have a blood test. You really need to leave 6 weeks. But 50mcg is also a very low dose. Often people don't feel any better till their dose is higher.

[Clutter]

Derrickbff,

Were your TSH and FT4 low when you were diagnosed? FT4 is currently 25% through range so I think you will need a dose increase to raise it.

[Hidden in reply to Clutter]

My T4 has been low or towards the bottom of the range for a couple years now. My TSH was normal. But I don't understand why the TSH is going hyper and my t4 is halted. Also experiencing heart palps and increased constipation, is this normal?

[Hidden in reply to Hidden]

But TSH has gone down since supplementation while t4 for the most part stays low.

[Clutter in reply to Hidden]

Derrickbff,

Your TSH is nowhere near going hyper. It has dropped because pituitary has detected more T4. T4 takes longer to respond than TSH. It can take up to six weeks to respond to a dose so T4 level may still be improving but it is likely you will need a dose increase to 75mcg to raise T4.

[Hidden in reply to Clutter]

Can low T4 by itself cause symptoms? Because my free T3 is always normal.

[Clutter in reply to Hidden]

Derrickbff,

It is low T3 which causes symptoms, not low T4 by itself.

FT3 is more stable than T4 and takes longer than T4 to respond to changes in levels. If T4 is low then FT3 is likely to be low, even though it may be within normal range.

[Hidden in reply to Clutter]

My t3 is consistently 3.4

Range 2.5 - 3.9 pg/mL

[Clutter in reply to Hidden]

Derrickbff,

That's excellent, just in the upper third of range.

[SlowDragon Administrator]

Essential to get vitamin D, folate, ferritin and B12 tested too

Low vitamin levels stop Thyroid hormones working

Do you have high thyroid antibodies? If so this is Hashimoto's also called autoimmune thyroid disease

You need to know. Ask that antibodies tested if not been done