Fishing for thyroid nodules: Why is a thyroid biopsy necesary?


Endocrinology, Medicine, Thyroid Disease

Thyroid nodules are like small lakes within the thyroid gland. These grow slowly with age and harbor the possibility of abnormal cells within them that should be examined by your doctor.

Today, many more imaging procedures are being done and people are more commonly being diagnosed with thyroid nodules. Most of the time, the original test ordered was not meant to look at the thyroid at all, but it may have picked up a small abnormality on the thyroid gland due to how close the thyroid is to other important parts of the neck. We will take a fishing trip so that you understand more about thyroid nodules. Thyroid nodules are like small lakes within the thyroid gland. Having small lakes in the thyroid is very common and the odds increase as you age. At 50 years old, 1/2 of all people have thyroid nodule lakes. As you get older, the lakes may fill with more water as they continue to grow slowly.


Because these lakes are within the thyroid itself, they cannot be seen with the naked eye. Similar to how fishermen use sound waves (ultrasound) to find the bottom of the water they are fishing in, doctors use an ultrasound machine to help visualize these thyroid lakes. Using the ultrasound, a doctor can tell how deep and wide the lakes are, how rough or smooth the borders are, and if there is any material floating within the water of the lake. While ultrasound may work to look at the lakes within the thyroid, it does not tell you anything about the type of fish swimming in thyroid lakes.

Because thyroid nodules are within the thyroid itself, they cannot be seen with the naked eye so doctors use sound waves (ultrasound) to find them and examine the cells within them.
Most thyroid nodules, approximately 95% of them are filled with healthy normal cells.

Most lakes are filled with healthy trout and other freshwater fish. In fact, 95% of thyroid lakes are filled with healthy fish.

However, a rare thyroid lake might contain dangerous fish. A piranha filled lake can be bad for your health. Most of the time, you can’t tell just by looking at a lake if it’s safe or if there are piranhas lurking. A fisherman would use his fishing pole to catch some fish to see what is in the water. Doctors use needles as their pole, and hope to catch cells instead of fish. This procedure is called fine needle aspiration biopsy. 5% of fishing trips in thyroid lakes discover dangerous, suspicious cells in them.

Only 5% of all thyroid nodules biopsied contain abnormal cells within them.

Doctors do not go fishing in very small lakes. After all, you are not likely to catch a fish in a super tiny lake. Doctor’s typically recommend fishing for dangerous cells only if the lake is greater than, or equal to, 1 centimeter. If a thyroid lake is larger (up to 4 centimeters), catching dangerous fish in that lake becomes more difficult. Sometimes the nasty piranhas can be tricky. Even though the fisherman tries to catch them, the piranhas can be hiding in a corner of the lake. In that situation, your doctor may recommend an operation to remove part, or all, of the thyroid.

Doctor’s typically recommend fishing for dangerous cells only if the nodule is greater than, or equal to, 1 centimeter. But also, if a thyroid nodule is larger, catching abnormal cells within them can be tricky as they could be hiding in the corners of the nodule itself.

About the Authors

Chris Palmeiro D.O. M.Sc.


Dr. Palmeiro is Chairman of Endocrinology at the HealthAlliance of the Hudson Valley, he also serves patients with intellectual and developmental disabilities at the Westchester Institute of Human Development in Valhalla, New York. He has a Masters of Science degree in clinical nutrition and is a diplomate of the American Board of Internal Medicine. His interests within the realm of endocrinology include nutrition support, obesity counseling and the progressive management of diabetes.


Rishi Anand M.D.

Dr. Anand is a board certified Endocrinologist. He graduated magna cum laude from the accelerated 7 year Renssaelear Polytechnic Institute-Albany Medical College combined physician scientist program. He practices Endocrinology in Bristol, PA. There, he treats a wide range of Endocrine disorders including diabetes, thyroid disease, and other hormonal imbalances.

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Last Modified: Jun 17, 2017 @ 3:18 pm

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Fishing for thyroid nodules
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Fishing for thyroid nodules
Learn everything you need to know about thyroid nodules, a very common condition for many patients. Diagnosis and rational for evaluating it.
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