Thyroid Testing and Diagnosis

Diagnosing 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.

Clinical Evaluation of the Thyroid

An important and baseline element of detecting and diagnosing thyroid disease is the clinical evaluation. A clinical evaluation of your thyroid should be conducted by a trained practitioner. While some general practitioners are capable of performing a thorough clinical examination of your thyroid, endocrinologists are often best trained in the specialized aspects of this diagnostic process.

Thyroid Disease Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Woman

As part of a thorough clinical evaluation, your practitioner typically should perform the following assessments:

  • Feel (also known as “palpating”) your neck, looking for enlargement, lumps, or irregularity in the shape of your thyroid.
  • Listen to your thyroid using a stethoscope to detect increased blood flow.
  • Test your reflexes. A hyper-response may be indicative of an overactive thyroid, and a blunted reflex response is often associated with hypothyroidism.
  • Check your heart rate, 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 are commonly linked to hyperthyroidism.
  • Measure your weight, and discuss changes. Unexpected weight gain is often linked to hypothyroidism, while weight loss is linked to hyperthyroidism.
  • Measure body temperature. A low body temperature is linked to an underactive thyroid, and a slightly elevated temperature is associated with 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 is linked to hypothyroidism, and unusually smooth skin is associated with hyperthyroidism.
  • Examine your nails and hands. Dry, brittle nails are linked to an underactive thyroid.
  • Review other clinical signs and symptoms.

Thyroid Blood Tests

When your practitioner suspects that you have a thyroid condition, a crucial step is blood tests to help come to a thyroid diagnosis.

Note: 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 or not prior to testing. For specifics, read The Optimal Time and Conditions for Thyroid Blood Tests.

The 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)

Interpreting Your Thyroid Tests

Understanding the different tests, what they mean, and how to interpret the results is essential for an informed, empowered thyroid patient. For additional information and understanding, read:

The TSH Test

The TSH test is considered by conventional practitioners as the "gold standard" thyroid test. There is, however, disagreement among even conventional medical experts about the normal reference range for this test. This disagreement can affect whether or not a practitioner diagnoses you with a thyroid condition, or excludes a thyroid diagnosis. To learn more about the TSH test, you will want to read:

Thyroid Imaging Tests

When your thyroid is enlarged, or potentially atrophied, and when nodules are detected or suspected, a variety of imaging tests may be performed to aid in diagnosis of your thyroid condition. These tests include:

  • Nuclear Scan/Radioactive Iodine Uptake. This test, also known as RAI-U, can tell whether you have Graves' disease, toxic multinodular goiter, or thyroiditis. (Note: it is not performed during pregnancy.)
  • CT Scan. A CT scan can help detect and diagnose goiter, or larger thyroid nodules.
  • MRI/Magnetic Resonance Imaging. MRI can help evaluate the size and shape of your thyroid
  • Thyroid Ultrasound. Thyroid ultrasound can evaluate nodules, lumps, and enlargement of your gland. Ultrasound can also tell whether your thyroid nodule is a fluid-filled cyst, or a mass of solid tissue.

Thyroid Biopsy/Fine Needle Aspiration (FNA) Biopsy

A needle biopsy, also known as fine needle aspiration (FNA) biopsy, is used to help evaluate suspicious thyroid lumps and nodules. In a needle biopsy, a thin needle is inserted directly into the nodule, some cells are withdrawn and they are evaluated for cancer. (Some practitioners also use ultrasound while conducting a biopsy in order to ensure that the needle goes into the right position.) While 95 percent 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 much more accurate, and very often can spare you unnecessary surgery for nodules that turn out to be benign.

Other Diagnostic Tests and Procedures

Practitioners 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

You will want to read more about these unconventional tests for thyroid disease before relying on their results.

The Thyroid 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.

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 your own thyroid tests. Some patients use this approach to get testing done before seeing a doctor. In other cases, it may be more affordable to have them done—with a markup—through your doctor. Or, your HMO or insurance may limit the tests your doctor can request.

Diagnosing Thyroid Conditions

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).

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.

Elevated results on antibody tests can help to detect underlying autoimmune thyroid diseases that may be causing hyperthyroidism, hypothyroidism, nodules, or goiter. In Hashimoto's disease, elevation of TPO antibodies is typically seen, and in Graves' disease, elevation in TSI antibodies. And the more controversial reverse T3 test detects overproduction of an inactive form of the T3 hormone, and is used by some integrative physicians to help identify thyroid imbalances.

For nodules and goiter, imaging tests can help to identify whether nodules are suspicious, at which point FNA biopsy is performed to assess nodules with suspicious characteristics to diagnose or rule out thyroid cancer.

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