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IAT 3mos later 16.4 Tg

Posts: 5
Joined: Feb 2007

I finished my ablation therapy November 14th. I just got an early Tg test and it is at 16.4. Does this seem high to anyone? I'll see my doctot on Feb. 7th. I guess I'll know more then.

Rustifox's picture
Posts: 110
Joined: Mar 2005

Hi, Nate
It isn't at all abnormal to still show a Tg level at this point. Ideally, we'd like to see it drop to undetectable after ablation, but often that is not the case.

Radioactive Iodine continues to kill cells over a long period of time, estimated to be 6 months or more, (some doctors believe a full year) after your treatment.

It is also estimated that roughly 25% of us require a 2nd radioactive iodine treatment to get rid of all remaining cells. Part of this can be size related - each dose generally penetrates depths of less than 1cm; the other part is dose related - was your dose high enough to do the job?

Some doctors believe that 100mCi's or more is required, depending on the amount of spread detected at surgery - 150mCi's or more if there is/was any spread outside the gland or in the lymph nodes.

In addition, some studies show those thyroglobulin numbers may continue to decline over the next 6 months or so, and that during that time, the dying tissues are expelling the last of their thyroglobulin because of cell death. This creates a situation similar to thyroiditis - which also causes thyroglobulin levels to increase significantly.

Either way, most experts do not recommend another RAI treatment for at least 6 months following your initial ablation. It is sometimes prudent to make sure (via ultrasound, and possibly an I-131 scan, or PET scan) that there are no remaining 'occult' areas that may be a concern, like a wayward lymph node.

If a lymph node is found, the best solution is to surgically 'debulk' any tissues, then follow with a repeated RAI down the line. Again - this is because radioactive iodine can only penetrate very minimal depth - in the millimetres rather than centimeters stages.

Lastly, I did also have a thyroglobulin level of 22 at one point - and now it reads as undetectable, both when I was hypo last year, and when I'm suppressed on synthroid, too, without requiring any further surgery of any kind.

Do you know what your TSH is? Your TSH level should be maintained - very important when we have thyroglobulin evident when on hormones - and needs to be at a level of .10 to .50 at a maximum, depending on your independant risk factors, including your age, the cells found, size of tumor, etc. TSH is assumed to 'feed' any remaining tissues, and with a detectable thyroglobulin level, suppression becomes even more important for us.

There is more information about this here, in a clinical document:
or if you prefer to read in more layman's terms, here is a good one, under the TSH Suppression heading:

The following document is often cited as the 'gold standard' of suppression outlines:

If you are interested, here is a set of 2006 guidelines for the complete treatment of thyroid carcinoma - they are clinical, for doctors and hospitals, but it may provide some extra data for you, too:

Hope this helps - the more I know, the more secure I feel, so I do read alot of the clinical guidelines, etc.

Some folks prefer not to read the clinical stuff, though - if it makes you feel anxious or overly concerned in any way, leave them to your doctors.

We each have to manage our care in the way it makes us most comfortable. All the best to you, and hope some of this is of value to you. Wishing you an undetectable thyroglobulin level by this time next year - so far, it has worked for me!

Posts: 5
Joined: Feb 2007

Thank you for the info. I like getting all the info. I can as well. My doctors sometimes feel like I read too much! For example, I read some articles pointing out that if your Tg is not below 10 by the end of the first year following IAT this is some evidence that you might have a more obstinate (less differentiated) form of papillary cancer.

You were at 22 Tg after IAT? If so, how many months later was it?

Regarding some of your questions. I am 28 years old. We know that the papillary cancer spread to some of my lymph nodes. I had a thorough neck dissection (4 hrs. long). I have a great experienced thyroid doctor who believes he got most of it out. I got my recent test results from my primary care Doc. My TSH was way to high (4.64). I started taking more T4 and T3 and I am positive my thyroid Doc. will push it up when I meet with him on Wed. I am at 200 mg T4 now + 12.5 T3.

Again thank you for your reply it is good to talk with someone.

Rustifox's picture
Posts: 110
Joined: Mar 2005

Mine was at 3 months, with TSH still a bit too high, but not as high as yours is, Nate... that TSH of yours needs to come down, pronto.

We do need to remember that thyroglobulin is also very TSH 'sensitive' - so that if your TSH is x, and your TSH is 10 times too high (which it is now), then thyroglobulin can 'multiply', too... for example, a thyroglobulin of 20 when we are in 'hypo' territory may be less than 2 when we are suppressed.

The guideline you speak of (the '10' number) is often cited as a hypo Tg level, simply showing (possible) remaining disease and/or healthy thyroid tissue remnant - which most of us will have following our initial ablation.

Remember, in the early stages of ablation/surgeries, both healthy and cancerous tissues will exude tg, and surgeons almost NEVER can get all the (remaining healthy) thyroid tissue even... they have to protect too many structures in our necks; 5 is usually the guideline for suppression thyroglobulin level after surgeries and ablation has eradicated all remaining tissue. Some conservative endos will use 2.0 as a guideline... but again, this is AFTER ablation(s) have been completed, ensuring all remnant (healthy) thyroid tissue has been killed off, too, and you are still in the early stages of that process.

The thing that 'may' indicate a more aggressive variant would be if your I-131 scans did NOT show any remaining tissues, yet your Tg level remains high (search under: thyroid carcinoma scan negative thyroglobulin positive).

Papillary (and even some follicular variants) are very similar to 'normal' thyroid tissue in their ability to 'suck up' the radioactive iodine treatment, as you know. As this cancer mutates to more aggressive variants, the ability/willingness of those tissues to 'suck up' the radioactive iodine decreases. Thyroglobulin is, in some ways, even a bit of a positive - anaplastic, for example, is often thyroglobulin negative... very unlike 'normal' thyroid tissues at all, if I remember correctly.

If you were to have an I-131 scan and show little or no uptake, and your thyroglobulin level were to continue to be above 10 as time progresses (and as your TSH comes down!), then most insurance companies will authorize your doctors use of a PET scan - Pet scans have the ability to detect those more aggressive tissues/sites when RAI won't, so there are options even if the tissues won't suck up the RAI to see what is going on in there.

With lymph node spread, many of the 'pro's' suggest at least 150mCi's, and some even 200mCi's of Radioactive iodine, following a stringent low iodine diet for 2 weeks prior to treatment, etc... if you do find that you need to have a second RAI treatment done (again, about 25% of us do need that), please make sure that you do the low iodine diet - really super carefully for the final 7 days prior to the dose, and for about 48 hours afterwards, too. It gives your body the best chance of 'sucking up' as much of the treatment as you can.

A very small node can produce a fairly significant amount of thyroglobulin, too. If I remember right (somewhere in the files at thyroidmanager.org), 1 gram of thyroid tissue/thyca can produce roughly 1.0 of thyroglobulin, so 20 grams is not very much tissue - still, if it is caused by a site, if it can be surgically removed it would be for the best in the long run. I tried to get you the link for the files that talk about this, but couldn't get into the 'neoplasia' adobe files tonight.

But again, you are still very 'early' out from your treatment to be too worried about this - most docs want to wait that 6 months to a year.

It is important to talk to people who understand what you are going through, Nate. Have you checked Thyca.org to see if there is a support group in your area? Just getting together for coffee with others who know about this too is worthwhile.

If I can help, send me an email through CSN; if I'm in town, I check my emails more frequently than I check in on this board, and CSN sends a message when someone emails me... you can email from my 'personal web page' on this site. Take care, and don't worry too much - glad to find another 'info addict'...lol. Sometimes the doctors don't like that too much, but I agree, it makes me feel like I have more control.

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