REPOST: Dr.'s Ain, Rolla & Spencer: re: tg --> Tom

[Guest guest]

Hello Tom,

You SNIPped an important major fact from the question-part of the post which

Dr. Ain addresses with his 1997 reply.

" one of the reasons for having a tt is that otherwise it is impossible to use

the TG test to detect recurrence "

Tom; the reason to know this is that regardless of the quantity of RAI or the

number of times that it has been prescribed (used); if a tt followed by RAI were

not performed..then.. tg readings are of little or no value as to assessing the

recurrence of thyroid cancer. (only as a relative indicator; specific to the

individual being tested) Also; it must be know if antibodies exist. (read Dr.

Rolla)

Dr. Ain _did_ address the question but it seems that you want to hear more

about it :-)

Nick

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>

>--Thyroglobulin is a specific product of thyroid follicular cells, both

>normal and malignant. There is no other type of cell in the human body which

>has been found to produce this protein. My laboratory, and many others, have

>studied the molecular biology and gene regulation of thyroglobulin and none

>of us have ever found (and published or made known) any exceptions to

>this.--Dr. Ain

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Date: Mon, 24 Apr 2000 13:04:45 -0400

Subject: REPOST: Dr. Ain Re: tg marker --> Ndal

In-reply-to:

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" In theory, patients with complete

>absence of thyroid cancer cells

>should have undetectable thyroglobulin levels (less than or equal to 1.0),

>both while hypothyroid and while on thyroid hormone. " Dr. Ain

Complete REPOST from Dr. Ain, follows, below.

tg straight answers

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(A repost from Dr. Carol Spencer ; a tg researcher in Calif)

>Thyroid 1999 May;9(5):435-41

>

>Detection of residual and recurrent differentiated thyroid

>carcinoma by serum thyroglobulin measurement.

>

>Spencer CA, LoPresti JS, Fatemi S, Nicoloff JT Department of Medicine,

>University of Southern California, Los Angeles 90033,

>USA. cspencer@...

>

>Thyroglobulin (Tg) measurement is primarily used to monitor patients with

>differentiated thyroid carcinoma (DTC) for tumor recurrence. Serum Tg

>levels principally integrate 3 variables: the mass of thyroid tissue

>present (benign or neoplastic); the degree of thyrotropin (TSH) receptor

>stimulation and tumor's intrinsic ability to synthesize and secrete Tg

>--a factor that needs to be assessed by a preoperative serum Tg

>determination.

>

>Serum Tg measurements should be interpreted relative to the TSH status

>of the patient. When TSH is low (on levothyroxine [LT4] therapy) basal

>serum Tg may be undetectable and recombinant human thyrotropin (rhTSH)

>administration may be needed to increase serum Tg into the measureable

>range. The Tg fold response to rhTSH (rhTSH-stimulated Tg/basal Tg) is

>an index of the tumor's sensitivity to TSH.

>

>Normal thyroid remnant and well-differentiated thyroid tumors display a

>greater (>10-fold) serum Tg response to TSH stimulation compared with

>less well-differentiated tumors (<3-fold). The factors influencing the

>response include the magnitude and chronicity of the serum TSH elevation,

>the mass of thyroid tissue and the TSH receptor status of the tumor.

>

>Technical problems still compromise the clinical utility of serum Tg

>measurement. Thyroglobulin autoantibodies are present in approximately

>20% of all DTC patients and cause either underestimation or overestimation

>of serum Tg measurements made by immunometric assay (IMA) and

>radioimmunoassay (RIA) methods, respectively.

>

>Other technical problems include poor interassay precision, " hook " effects

>(IMA methods), intermethod standardization differences, and suboptimal

>sensitivity for detecting small amounts of tumor during TSH

>suppression. When TSH is suppressed, the basal serum Tg provides an

>integrated index of thyroid tissue mass and its capability to secrete Tg.

>Serial measurements of basal Tg concentrations can be used to monitor

>tumor progression or regression. The development of a low (<1 ng/mL)

>serum Tg (on LT4 therapy) by the second postoperative year signifies a

>low 5-year recurrence risk whereas a rising serum Tg in the face of TSH

>suppression is an abnormal response consistent with recurrence. The

>optimal degree of TSH suppression for a patient should be based on

>clinical judgment, relative to tumor staging and the risks from

>iatrogenic hyperthyroidism.

>

>Despite current technical limitations, serum Tg measurement is the

>cornerstone of long-term monitoring for most DTC patients. For optimal

>use of serum Tg, it is necessary to understand the pathophysiology of Tg

>secretion, the limitations of Tg methods and the use of rhTSH to overcome

>the insensitivity of current Tg methods.

>

>

>

>

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At 6/14/01 03:42 PM, you wrote:

>Nick,

>

>Your reposting of Dr. Ain's info from 1997 does not seem to me, to

>address the question posted above it, from 2001, specifically:

>

>SNIP " Isn't it true that after receiving doses of RAI of 100 or more

>mCi, then a TG is valuable in testing for thyca recurrence? I have

>received RAI 100 mCi,150 mCi and 60 EBR. My endocrinologist,

>radiation oncologist and now thyca specialist are using my last two

>TG results of 13 and 39 as indication of recurrence with possible

>mets. I have previously gone down to zero or near zero only to go up

>again. This is what has made my doctors believe I do in fact have

>cancer for a forth time. The test results I stated are while

>suppressed with Synthroid. " SNIP

>

>I would be interested in seeing an answer to that specific question,

>in lieu of a general statement, which although informative, does not

>address the actual question.

>

>Thanks!

>Tom