Thyroid Tests

Q: What are the tests that might be performed for a thyroid tumor or mass?

A: There are a number of tests that can be performed for the presence of a thyroid tumor. Some of them are, in fact, useful, but many are simply a waste of time and money and contribute nothing to the diagnosis. We will often see a patient in the office with thousands of dollars worth of tests that were simply unnecessary. Probably the best test for a thyroid tumor is the experienced fingers of a thyroid surgeon. But let's briefly look at the more common tests available.

Blood tests - Occasionally the level of thyroid hormone in the blood may contribute to the diagnosis of a thyroid tumor. Also, antibodies in the blood may help diagnose a condition called chronic thyroiditis - a disease that can sometimes create a thyroid mass and mimic a thyroid cancer. At this time, there is no blood test that can specifically diagnose thyroid cancer.

Thyroid scan - This is a radioactive picture of the thyroid gland that can tell us if a tumor is "functioning" or "nonfunctioning". This can sometimes be helpful, but since some thyroid cancers function and some do not, it cannot diagnose thyroid cancer.

Thyroid Ultrasound - This test is a sort of "sonar" that may tell us if a thyroid tumor is solid or cystic, cystic meaning hollow and fluid filled. This can be of some interest since thyroid cysts are rarely cancerous. Still, in most cases skilled fingers can discern between the two types of masses without this test. You, for example, could probably tell the difference between a golf ball and a ping pong ball if you were handed them while blindfolded. Also, many thyroid tumors can be partially solid and partially cystic, further confusing the matter because either might be malignant or benign.

CAT Scan or MRI - These are high tech and high cost forms of x-rays that are rarely indicated in the evaluation of a thyroid mass. Once in a very rare while, a complicated or difficult case may come along where this would be indicated. Rarely.

Needle Biopsy or Fine Needle Aspiration - This test is somewhat controversial. Some physicians are fond of it, and others feel its usefulness is actually quite limited. The accuracy rate of this test in the evaluation of follicular cancer is only around 50%. For papillary cancer it is much higher, perhaps 90% to even 95%. A lot depends upon the pathologist who is looking at the cells removed by the needle. Unfortunately, the biopsy report will often say such things as "inadequate specimen" or "thyroid cells present", or "compatible with..." or "suggestive of ...". None of these "impressions" are helpful since they do not give us a clear and precise diagnosis. Also, it has been our experience that when a patient comes to our office with a diagnosis of definite thyroid cancer on needle biopsy, the tumor in the gland felt suspicious on physical exam alone, such that thyroid surgery would have been recommended regardless of what the needle biopsy seemed to indicate. Therefore, doing the needle biopsy was unnecessary. Also, while rare, there is the possibility of cancer cells being spread by the needle biopsy. We have seen only one case of this. Finally, needle biopsy is sometimes a somewhat painful procedure.

Fine needle aspiration has a place in the evaluation of some thyroid tumors, but it is our opinion that it should not be used before the patient has been seen and evaluated by an experienced thyroid surgeon.


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