Thyroid nodules: detection

Tests for thyroid nodules include ultrasound examinations, radioactive iodine scans, and fine needle aspiration biopsies (FNAB). The FNAB is the most definitive test for a diagnosis of the nodule type.

What is a fine needle aspiration biopsy (FNAB) of the thyroid?

This is the most important test used to assess the cause of an enlargement or lump in the thyroid gland. A small needle is placed into the thyroid and a microscopic amount of thyroid tissue is obtained in the needle tip. Many physicians will attach the needle to a special syringe so tissue can be "aspirated" or "sucked" back into the needle. The small sample of tissue is then taken to a hospital pathologist – a physician specializing in tissue specimens – for interpretation.

Usually, the FNA test can be done as a brief office procedure that does not require any painkillers. The degree of discomfort is similar to having your blood drawn for routine blood tests. The procedure of FNAB, especially the interpretation of the thyroid specimen, requires physicians trained and experienced in this technique.

What can a fine needle aspiration biopsy determine?

A fine needle aspiration biopsy generally leads to one of four different results. The results of the FNAB help determine the next step in investigation or the therapy required.



Benign nodule

Benign thyroid nodules can either be observed or suppressed by taking thyroid hormone pills.

Suspicious for thyroid cancer

Suspicious biopsy results require close follow-up with additional testing and often a repeat fine needle biopsy. Although many of these cases turn out to be a thyroid cancer, many are ultimately proven to be benign.

Thyroid cancer

Thyroid cancers should be removed by surgery.

Insufficient biopsy: either not enough tissue was obtained or the sample was not sufficient to allow an exact diagnosis.

Insufficient biopsies need to be repeated in order to obtain a better sample of tissue with which a pathologist can provide an exact diagnosis.

Flow-chart for findeneedle aspiration biopsyWhat is an ultrasound examination?

Ultrasound is a way of scanning the human body using sound waves. It is painless, uses no radiation and is relatively fast to perform. Sound waves are sent into the body and an image of body tissues is created by analyzing how the sound waves "bounce off" body structures. Because no radiation is used, thyroid ultrasound examinations are safe during pregnancy.

What is a radioactive iodine uptake and scan test?

This test is available in the nuclear medicine department of most major hospitals. A small dose of radioactive iodine is taken orally and will show how metabolically active the thyroid tissue is.

The iodine is temporarily absorbed by the thyroid gland. The patient lies under a special scanner that detects any radioactivity given off by the iodine. Radioactive iodine is tasteless and painless to take, and although the dose of radiation is considered very low and safe to take, this test should not be performed on pregnant women or mothers who are breast-feeding.

Dr. Richard Bebb, MD 
in association with the MediResource Clinical Team 

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