Hello again, actually I posted a result about my TSH level increase hours ago but while looking in to results I realized that, although my Tg is <0.04 my anti tg is :
AntiTg 13.3 IU/mL 0 - 115
I had total thyroidectomy 8 years ago and had RAI.
My previous post:
Well, it's negative. Are you worried about it? I really don't think it's anything to worry about. It's not doing any harm. 
I guess I misunderstood sth I read about non-zero Anti-TG then. I expected it to be near 0 like Tg. Since it is 13.3 IU/mL in range of 0 - 115.
Did you have the TT due to cancer?
It may not be zero - I've never seen a zero antibody result in anyone - but it's nearer to zero than it is to 115, so really nothing to be concerned about.
The < means less than - so even if you have a trace lower than that its not detectable by the lab equipment.
A small level of anti TG is found in most and it’s not considered positive until it rises above the upper limit.
I don’t think you need to be concerned.
Which country are your tests & treatment? (Add country to profile)
If it makes you feel any better, mine is always 14 and my endocrinologist is never concerned. He has not even mentioned. I was somewhat concerned but since he did not acknowledge it as a concern, I left it alone. One less thing to worry about! Doctors communication skills are poor, that leaves us patients to worry unnecessarily. You’re not alone!
My Thyroglobulin antibodies (TgAb) are zero. In the major US labs, if TgAb are at all positive (i.e. not zero) then the Tg is run using mass spectrometry to avoid interference. Antibodies can cause false negatives or false positives. Also important you're not taking any biotin in any form as it also interferes with testing.
Positive antibodies with negative Tg isn't a concern unless they are very high (as PurpleNails pointed out) and continue to trend upward. But I would be concerned with the high TSH which can encourage any remnant thyroid cells to grow (even if you've had RAI).
Patti in AZ
I had thyroid cancer and I have negative Tg and I have recurring cancer been dealing with it for close to two years…. I have a nice neck lump problem with this is Endo’s don’t want to react because the Tg is negative so they can’t wrap their heads around this… My body never ever does what the protocol says for anything.
I came across a research article which suggested all thyroid cancer patients should have Tg tested before surgery to ensure it can be use as a surveillance marker as some people are Tg "low-producers". And lymph nodes may not produce detectable blood levels of Tg.
Won't your doc/s do an ultrasound and FNA, (preferably with a thyroglobulin washout). The washout is important for confirming if the FNA slides are indeterminate. (Where the needle and syringe are rinsed with saline then the fluid checked for Tg.) academic.oup.com/jcem/artic...
Patti in AZ
I have scans done every year and Thyrogen and everything says I have recurring thyroid cancer but the Tg says otherwise …. The Tg was done before the thyroidectomy and it came back as undetectable…. Im a mystery!
In many cars, if you look at the speedometer when you are absolutely stationary, it will indicate something like 5 or 10 miles per hour.
It doesn't mean you are actually rolling down the road. It is just that there is a range at the bottom of the speedo where the manufacturer has put a 'stop'. It prevents the needle twitching at very low speeds, and avoids some sort of implication that the needle is accurate when so close to zero.
In the same way, the bottom ends of lab tests have a sort of dead patch which means absolutely nothing.
Some labs, for some tests, simply report positive or negative (maybe a bit in the middle that is not definite).
Selenium methionine and Total Thyroidectomy
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Total thyroidectomy too low TSH normal T4
