hypothyroidism tests

6 Essential Tests for Diagnosing Hypothyroidism and Procedure,Results

Hypothyroidism is one of the most widely prevalent thyroid problems that happen due to an underactive thyroid. It is more common among women over the age of 50 years. The main problem with hypothyroidism is that it is one of the most unrecognized, undiagnosed and misdiagnosed health problems despite its clear symptoms such as excessive dry skin, unexplained fatigue, intolerance to cold and abnormal weight gain. Proper diagnosis of hypothyroidism using hypothyroidism tests can allow early access to treatment which may significantly improve your quality of life.

Most Important Hypothyroidism Tests

Diagnosis and treatment of hypothyroidism are dependent on your symptoms and results of the thyroid blood test that measures TSH levels (thyroid stimulating hormone) along with levels of thyroid hormone thyroxine. Low level of thyroxine and high level of TSH means you have an underactive thyroid. This happens because the pituitary releases more TSH in order to stimulate the thyroid gland so that it produces more thyroid hormone.

TSH Test:

This is the most effective screening test which helps the doctors to diagnose thyroid disorders at an early stage, even before the patient experiences any serious symptoms. The TSH test measures the amount of thyroid stimulating hormone present in your blood. This test detects even tiny amounts of TSH in the blood. The health care provides takes a blood sample for this test. No special preparation is required for this test. Talk to your health care provider about the medicines and nutritional supplements you are taking and whether they can affect the test results.

Results of the TSH Test are as follows:

0.4: Normal
2.5: At risk
4.0: Mild hypothyroidism
10.0: Hypothyroidism

  • Higher than normal result indicates an underactive thyroid gland or hypothyroidism.
  • Lower than normal result indicates an overactive thyroid gland which can be caused by Graves’ disease, toxic nodular goitre or excessive iodine in the body.

Free T4Test:

Free thyroxine (T4) test helps to evaluate thyroid function and diagnosethyroidproblems such as hyperthyroidism and hypothyroidism. This test is done after the TSH test when you record abnormal TSH levels. T4 along with another hormone named triiodothyronine (T3) are released by the thyroid gland. These hormones control the rate at which the body uses energy and TSH stimulates the production of T4 and T3. Free T4 test helps to detect too much or too little thyroid hormone and diagnose the causebehind this abnormality. It helps to distinguish between differentthyroid disorders, identify pituitary disorders and record the effectiveness of the treatment.

Results of the Free T4 test:

A high Free T4 result indicates overactive thyroid gland (hyperthyroidism)
Low Free T4 result indicates underactive thyroid gland (hypothyroidism)

Free T3 Test:

A Free triiodothyronine (T3) test is done to understand and access thyroid functions. Your doctor may order this test to monitor your treatment. Most of the T3 is bound to protein and thus, the total T3 is affected by protein levels and protein binding ability. But this is not the case for free T3. Free T3 is often used to diagnose Graves’ disease. Increased or decreased levels of hormone in the results indicate an imbalance between the requirements and supply within the body, but it does not specifically reveal the cause of the excess or deficiency.

Reverse T3 Test:

The reverse T3 test, also known as Reverse Triiodothyronine and RT3is done to evaluate thyroid function and metabolism. Reverse T3 is an inactive form of T3 that is produced during stressful situations. Doctors who focus on optimal hormone balance view the Reverse T3 test as a vital test for the diagnosis and management of hypothyroidism. Elevated levels of Reverse T3, even though TSH and Free T3 values may be within normal range indicate a thyroid problem at the cellular level, often called “cellular hypothyroidism”. Reverse T3 can be measured with the help of a blood test.

Thyroid peroxidase antibody test:

Thyroid peroxidase (TPO) is an enzyme that is found in the thyroid gland and it plays an integral role in the production of thyroid hormones. A thyroid peroxidase antibody test (TPO test) helps to identify the antibodies against TPO present in the blood. Your doctor may recommend a TPO antibody test in combination with other thyroid tests in order to determine the cause. This test helps to differentiate thyroid autoimmune disorders from goitre or hypothyroidism and also helps to decide if a patient has to be treated for subclinical hypothyroidism.

The presence of TPO antibodies in your blood means that your thyroid disorder is being caused by an autoimmune disorder such as Graves’ disease or Hashimoto’s disease.

Thyroglobulin Antibodies Test:

Thyroglobulin antibodies test, also known as TgAb is a test that checks the levels off antibodies in the blood that is produced against the compound thyroglobulin. Thyroglobulin is a protein that is produced and used by the thyroid gland to produce the hormones triiodothyronine (T3) and thyroxine (T4). In people with thyroid-related autoimmune conditions, the level of thyroglobulin antibodies in the blood may rise. This test helps to detect possible thyroid problems.

Results of the Thyroglobulin Antibodies Test:

Normal Results:

A negative test result is normal. It means no antibodies to thyroglobulin have been found in the blood.

Abnormal results:

A positive test result means antithyroglobulin antibodies have been found in the blood. Some of the common causes of abnormal results are:

  • Hypothyroidism
  • Graves’ disease
  • Hashimoto thyroiditis
  • Thyrotoxicosis
  • Systemic lupus erythematosus

You may be required to fast for several hours before the test (usually overnight). Your doctor may stop you from taking certain medications (blood thinners) temporarily because these medicines may interfere with the test results.

Physical exams, blood tests and a thorough examination of the medical history are the primary steps in diagnosing hypothyroidism or subclinical hypothyroidism. The results of these tests help the doctor to put the patient on a successful treatment path. If you notice symptoms such as excessive fatigue, unexplained weight gain, dry skin, constipation, etc. and suspect that you are at risk of hypothyroidism then do not hesitate to discuss various thyroid test options with your doctor.

Medically Reviewed By
Dr. Kaushal M. Bhavsar (MBBS, MD)Assistant Professor in Pulmonary Medicine, GMERS Medical College, Ahmedabad