What is a TBG lab test?

[okaykay]

I was looking over my lab sheet for labs to be taken in two weeks and noticed my GP ordered Thyroid binding Globulins.

It sounds like a reverse t4 when trying to understand it? I thought they ordered a TGab, but apparently that was not the case.

What exactly will this result tell me? Oh how all your knowledge is greatly appreciated. I will check for replies tomorrow.

[helvella Administrator Thyroid UK]

What Abnormal Results Mean

An increased TBG level may be due to:

Acute intermittent porphyria (a rare metabolic disorder)

Hypothyroidism (underactive thyroid)

Liver disease

Pregnancy (TBG levels normally increased during pregnancy)

Note: TBG levels are normally high in newborns.

Decreased TBG levels may be due to:

Acute illness

Acromegaly (disorder caused by too much growth hormone)

Hyperthyroidism (overactive thyroid)

Malnutrition

Nephrotic syndrome (symptoms that show kidney damage is present)

Stress from surgery

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Not often done.

[okaykay in reply to helvella]

Is it a waste having already been diagnosed with hashimots thyroiditis? I have never had a total T4. Could it be a good thing since they never run it? I think they rush at times printing lab sheets and make mistakes. So frustrating. 🤨

[diogenes Remembering]

This test is for the principal protein circulating in blood that carries T4 and T3 to the body's tissues for them to take up what they need. In the healthy population the amount of this protein in 95% of cases can vary by a factor of two. The actual amount of T4 bound on will also vary accordingly. But rare people exist with no blood TBG at all, and others with 4 times the average. These differences can affect T4 results especially for total circulating T4, which makes this measurement much less accurate than Free T4 which is the amount of hormone actually entering the body cells.

[okaykay in reply to diogenes]

I have a free T4 ordered with that. Is the TBG a waste? My Ft4 has held pretty steady at 1.3 for over a year. It’s my FT3 that’s been changing. Would total T4 be more informative? I replied to both of you that responded. 😬 oops