Thyroid Testing and Diagnosis

Getting a diagnosis of thyroid disease is a process that incorporates a number of different types of examinations, including clinical evaluation, blood tests, imaging tests, biopsies, and other tests. Let's take a look at the various components of the thyroid diagnosis process.

Thyroid disease diagnosis
Illustration by JR Bee, Verywell.

Clinical Evaluation

An important and baseline element in the detection and diagnosis of thyroid disease is clinical evaluation. A clinical evaluation of your thyroid should be conducted by a healthcare provider, a general practitioner, or an endocrinologist.

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As part of a thorough clinical evaluation, your healthcare provider typically will perform the following assessments:

  • Feel (also known as “palpating”) your neck for enlargement, lumps, or irregularity in the shape of your thyroid.
  • Listen to your thyroid using a stethoscope to detect blood flow abnormalities.
  • Test your reflexes. A hyper-response is often present with an overactive thyroid, and a blunted reflex response can occur with hypothyroidism.
  • Check your heart rate, heart rhythm, and blood pressure. Lower heart rate and/or blood pressure can be associated with an underactive thyroid, and elevated heart rate and/or blood pressure can occur due to hyperthyroidism.
  • Measure your weight and discuss any changes. Unexpected weight gain often accompanies hypothyroidism, while weight loss can occur due to hyperthyroidism.
  • Measure body temperature. Low body temperature can develop due to an underactive thyroid, and a slightly elevated temperature may occur due to hyperthyroidism.
  • Examine your face for thyroid-related signs, including loss of the outer eyebrows, puffiness in the eyes, and unusual rashes.
  • Examine your eyes, looking for classic thyroid signs, including bulging of eyes, a prominent stare, and dry eyes.
  • Observe the general quantity and quality of your hair. Changes in the texture of hair, as well as hair loss and breakage, are associated with both hyperthyroidism and hypothyroidism.
  • Examine your skin. Dry, rough skin can be a sign of hypothyroidism, and unusually smooth skin can be a sign of hyperthyroidism.
  • Examine your nails and hands. Dry, brittle nails can result from an underactive thyroid.

Blood Tests

When your healthcare provider suspects that you have a thyroid condition, they will likely order blood tests to measure your thyroid hormone levels.

Before you have blood tests done, you will want to understand your options in terms of the timing of testing, and whether to fast and/or take medications prior to testing.

Common thyroid blood tests include the following:

  • Thyroid-stimulating hormone (TSH) test
  • Total T4/total thyroxine
  • Free T4/free thyroxine
  • Total T3/total triiodothyronine
  • Free T3/free triiodothyronine
  • Reverse T3
  • Thyroglobulin/thyroid-binding globulin (TBG)
  • Thyroid peroxidase antibodies (TPOAb)/antithyroid peroxidase antibodies
  • Thyroglobulin antibodies/antithyroglobulin antibodies
  • Thyroid-receptor antibodies (TRAb)
  • Thyroid-stimulating immunoglobulins (TSI)

These tests can measure thyroid hormones in their different forms, as well as measuring proteins that can increase or decrease your thyroid hormone production. Your healthcare provider will look at the combination of results to determine the type and cause of your thyroid condition.

Interpreting Your Results

Thyroid test results involve many different parameters, and some of your levels can be elevated, while others are decreased. The pattern of these results helps your healthcare provider understand your thyroid disease.

Normal ranges may vary by lab, so keep that in mind if you are looking at your results.

Examples of test results and their significance in thyroid disease:

  • Elevated antibody levels may indicate underlying autoimmune thyroid disease. Different antibodies can indicate hyperthyroidism, hypothyroidism, nodules, or goiter. With Hashimoto's disease, you can have high TPO antibodies, and with Graves' disease, you can have high TSI antibodies.
  • The more controversial reverse T3 test detects overproduction of an inactive form of the T3 hormone and may be used by some integrative healthcare providers.

Your healthcare team can help you understand what your results mean in relation to your unique situation.

The TSH Test

The thyroid-stimulating hormone (TSH) test is considered an important thyroid test. If your thyroid hormones are low, sometimes TSH can be elevated as your body attempts to compensate. And sometimes TSH is low if your thyroid hormones are too high.

For example:

  • An elevated TSH—along with lower T4/free T4 and lower T3/free T3 levels—is associated with hypothyroidism.
  • Low TSH—along with higher T4/free T4 and higher T3/free T3 levels—is associated with hyperthyroidism.

However, sometimes thyroid disease can be complicated, so the results aren't always so straightforward.

Ordering Your Own Thyroid Blood Tests

You may not be aware, but in most states in the U.S., and some areas outside the U.S., you can order and pay for your own thyroid tests. Some people use this approach to get testing done before seeing a healthcare provider.

It may be more affordable to have your tests done through your healthcare provider, however. Sometimes, your HMO or insurance may limit the tests your practitioner can request.

Imaging Tests

Imaging tests can be used to identify thyroid enlargement, atrophy, or nodules in diagnosis of your thyroid condition.

These tests include the following.

  • Thyroid ultrasound: Thyroid ultrasound can visualize nodules, lumps, and enlargement of your gland. Ultrasound can be used to help your healthcare provider see whether your thyroid nodule is a fluid-filled cyst or a mass of solid tissue.
  • Nuclear scan/radioactive iodine uptake: This test, also known as RAI-U, can identify signs of Graves' disease, toxic multinodular goiter, or thyroiditis. (Note that it is not performed during pregnancy.)
  • CT scan: A CT scan can provide a picture that shows a goiter or larger thyroid nodules.
  • MRI/magnetic resonance imaging: MRI can help evaluate the size and shape of your thyroid

Biopsy

A needle biopsy, also known as a fine needle aspiration (FNA) biopsy, is used to help evaluate suspicious thyroid lumps and nodules. During a needle biopsy, a thin needle is inserted directly into the nodule, and cells are withdrawn and evaluated in a laboratory for cancer. Some healthcare providers use ultrasound while conducting a biopsy to guide the needle position.

While 95% of thyroid nodules are not cancerous, FNA, along with some additional tests such as the Veracyte Afirma test, can make the results of your biopsy more accurate and may spare you unnecessary surgery for nodules that turn out to be benign.

Other Diagnostic Tests

Healthcare providers sometimes use other tests and procedures to identify thyroid dysfunction. The use of these tests is considered controversial to mainstream practitioners, but some of these tests are accepted and in use among alternative, integrative, and holistic physicians.

These tests include:

  • Iodine patch tests
  • Saliva testing
  • Urinary testing
  • Basal body temperature testing

The reliability and value of these tests have not been established. If your healthcare provider recommends this test, they should help you understand what information it will provide them and how you can best prepare for it.

Neck Check Self-Test

While it is not considered diagnostic, you can perform a self-check of your neck to look for lumps and enlargement.

In general, a neck check is not considered to be reliable or accurate compared to other available testing methods. It may provide a false negative—you can have thyroid disease even if your neck feels completely normal. However, a self-check doesn't hurt to do and is simple and straightforward.

With your fingers, you'll gently feel for lumps in your neck as you swallow a sip of water.

how to do a thyroid neck check
Illustration by Emily Roberts, Verywell

A Word From Verywell

Based on the results of a clinical examination, blood tests can detect key thyroid conditions, including hypothyroidism (insufficient thyroid hormone) and hyperthyroidism (excess thyroid hormone). For nodules and goiter, imaging tests can help to identify whether nodules could be cancerous, and FNA biopsy is performed to assess nodules with suspicious characteristics to diagnose or rule out thyroid cancer. With this combination of tests, a healthcare provider can make an accurate diagnosis and provide you with treatment.

Frequently Asked Questions

  • How do you prepare for a thyroid blood test?

    Fasting for several hours before your thyroid function blood test may be necessary. Otherwise, there’s nothing special you need to do before a thyroid test.

  • Can a saliva test be used to diagnose hypothyroidism?

    No, saliva tests cannot be used to test thyroid hormone levels.

  • Is a thyroid biopsy painful?

    No, it shouldn’t be. A fine needle is inserted through the neck and into the thyroid to take a sample. The needle is very small and there should be little pain during or after the procedure. Your healthcare provider may use a local anesthetic to numb the area before inserting the needle. Pain medication can be used afterward to relieve mild discomfort.

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Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading