Thyroid Test in Hyderabad, India | Home Collection & Price

Thyroid tests include blood tests and imaging tests.

Thyroid blood test

Blood tests for measuring thyroid hormones are widely available and commonly used, but only some are applicable in certain situations.

Thyroid test procedure

Healthcare professionals may order one or more blood tests to diagnose the functioning of the thyroid gland by checking the levels of the thyroid hormones. These tests include:

• TSH
• T4
• T3
• Thyroid antibodies test
• Thyroglobulin test

To perform these tests, a healthcare professional draws blood from the patient's arm and sends it to a lab for testing.

TSH tests

TSH is a hormone produced by the pituitary gland that signals the thyroid to produce T4 and T3 and controls the amount of production. 

The TSH test is the most accurate initial test for thyroid function to measure TSH levels in a blood sample. The reference range of normal thyroid-stimulating hormone (TSH) findings for adults is between 2-10 μmL, newborns 3-18 μU/mL, and for cord is 3-12 μU/mL.

A normal TSH level indicates proper thyroid functioning in most healthy people. Changes in TSH levels may serve as an "early warning system," frequently occurring before the body's actual level of thyroid hormones becomes too high or too low.

A high TSH level indicates primary hypothyroidism or underactive thyroid, where the thyroid gland is not making enough thyroid hormone (hypothyroidism), resulting in continuous secretion and release of TSH into the blood by the pituitary.

Other conditions associated with an increase in TSH include:

• Congenital hypothyroidism.
• TSH-secreting pituitary tumours (uncommon).
• Pituitary resistance to thyroid hormone (uncommon)

A low TSH level usually indicates hyperthyroidism or an overactive thyroid, where the thyroid makes too much hormone, resulting in a stoppage of secretion and release of TSH by the pituitary.

Other conditions that are associated with a decrease in TSH levels include pituitary hypothyroidism (rare) and non-thyroid illness.

Rarely, a low TSH may occur from an abnormality in the pituitary gland, preventing the adequate production of TSH to stimulate the thyroid (secondary hypothyroidism).

Indications for TSH testing may include:

• Diagnosis and monitoring of other thyroid disorders
• Screening for congenital hypothyroidism in newborns
• Screening for subclinical hypothyroidism
• Monitoring of patients those who receive thyroid hormone

T4 test

T4 thyroid test measures the amount of thyroxine (T4) in the blood. The thyroid gland makes T4 in response to thyroid-stimulating hormone. T4 is found in two forms: free T4 (active form) and bound T4. More than 99% of T4 is found in the bound form. Free T4 travels to body tissues where it is needed. On the other hand, bound T4 attaches to proteins that prevent it from entering these tissues. 

It can be measured with either a total T4 test or free T4 test. The total T4 test measures free (unbound) and bound T4 together. A free T4 (FT4) test directly measures the amount of free T4 in the blood.

Tests measuring free T4 – either a free T4 (FT4) or free T4 index (FTI) – more precisely reflect thyroid gland function when tested with TSH.

• The presence of an elevated TSH alongside low FT4 or FTI indicates primary hypothyroidism resulting from thyroid gland disease.
• The finding of low TSH levels and low FT4 or FTI suggests a hypothyroidism condition resulting from an issue involving the pituitary gland. 
• The presence of a low TSH with a high FT4 or FTI indicates hyperthyroidism.

In some circumstances, high or low thyroxine (T4) levels may not indicate that a person has thyroid problems. For example, thyroid levels are high if the person is pregnant or taking oral contraceptives, and they are low when the person is having severe illness or using corticosteroids. The conditions mentioned above and medications may alter the amount of proteins that bind or attach to T4 in the blood.

As stated earlier, the human body reserves the bound T4 in the blood by binding it to proteins until needed. Free T4 hormone is not bound to these proteins and can enter the body tissues as required. Changes in the levels of binding proteins don't affect free T4 levels. Hence, many healthcare professionals most of the time prefers to measure Free T4.

T3 test

If a healthcare professional suspects hyperthyroidism despite a normal T4 level, a T3 test may be ordered to confirm the diagnosis. Sometimes, when T4 is normal but T3 is high, measuring both T4 and T3 levels can help diagnose hyperthyroidism.

T3 tests are often recommended to diagnose hyperthyroidism condition or to specify the severity of the hyperthyroidism.

Hyperthyroid patients with hyperthyroidism have elevated or high levels of T3. In some patients with low TSH levels, only the T3 is elevated, while the FT4 or FTI remains normal.

Rarely the T3 test is helpful in hypothyroid patients, as it is usually the last test to show abnormalities. High TSH and low FT4 or FTI and normal T3 indicate the patient may be severely hypothyroid..

• Free T3: Free T3 levels are also measured; however, it is often unreliable and, therefore, not typically helpful.
• Reverse T3: This protein is biologically inactive and structurally identical to T3 but with iodine atoms placed differently, resulting in its inactivity.

Some reverse T3 is usually produced in the body but is then rapidly degraded. In healthy, non-hospitalized people, measuring reverse T3 does not help determine the existence of hypothyroidism and is not clinically useful.

Thyroid antibody tests

The human immune system contains lymphocytes, which are the white blood cells that produces antibodies. They protect the body from foreign invaders (bacteria and viruses) and destroy them.

However, in some patients with hyperthyroidism or hypothyroidism, lymphocytes may mistakenly attack the thyroid gland by producing antibodies against thyroid cell proteins, resulting in thyroid autoimmunity (a reaction against the thyroid).

Two common thyroid antibodies are thyroid peroxidase and thyroglobulin antibodies; measuring their levels may help identify the underlying cause of the thyroid problem and diagnose the following autoimmune thyroid disorders:

• Graves' disease: most common cause of hyperthyroidism
• Hashimoto's disease: most common cause of hypothyroidism.

For example, if a patient with hypothyroidism has positive antithyroid peroxidase or anti-thyroglobulin antibodies, it indicates "Hashimoto's thyroiditis".

If the patient has Graves' disease, a healthcare professional might also order a thyrotropin receptor antibody test (TSHR or TRAb), which detects blocking and stimulating antibodies.

In Graves patients, measuring antibody levels helps evaluate the response to treatment of hyperthyroidism, determine the appropriate timing for discontinuing antithyroid medication, and assess the risk of passing thyroid antibodies to the foetus during pregnancy.

In a patient with hyperthyroidism, a different antibody that may be positive is the stimulatory TSH receptor antibody (TSI), causing the thyroid to be overactive in Graves' Disease.

Detecting the thyroid antibodies is helpful for the initial diagnosis of hypothyroidism condition due to autoimmune thyroiditis; however, tracking their levels over time is not beneficial for detecting the development of hypothyroidism or response to therapy.

Thyroglobulin

Thyroglobulin is a type of tumor marker test which measures the level of thyroglobulin, a protein made by the thyroid. Tumor markers are essential substances produced by normal cells and cancer cells in response to cancer in the body. However, thyroglobulin testing does not help diagnose thyroid cancer because other thyroid conditions that aren't cancer also affect levels of thyroglobulin. 

A person requires a thyroglobulin test before initiating treatment for thyroid cancer and also used in those who had surgery for thyroid cancer to monitor them after treatment. This is also mainly used to:

• Check if thyroid cancer treatment was successful.
• Make decisions about further treatment
• Check the re-occurrence of cancer after successful treatment in patients with a history of thyroid cancer

Understanding the results of a thyroglobulin test is complicated because the results depend on a patient's overall medical history, the type of treatment, and the results of other tests.

In general, if the patient is tested after treatment for thyroid cancer:

• Normal values: 3 to 40 nanograms per milliliter is the normal range for thyroglobulin in a healthy patient.
• No thyroglobulin or very low levels: It suggests the cancer treatment has worked to eliminate all cancer tissue in the thyroid. However, more testing may be needed over time to make sure. 
• Elevated thyroglobulin levels: It indicates that the given treatment did not eliminate all thyroid tissue. The patient still has thyroid cancer in the body that has developed and may have spread.
• Thyroglobulin levels were low after therapy but later elevated, which may indicate that thyroid cancer has come back after treatment.
  

Non-blood tests for thyroid

Radioactive iodine uptake test

A radioactive iodine uptake test, also known as a thyroid uptake test, can help examine thyroid function. When a person consumes iodine, the thyroid gland has small cells that absorb the circulating iodine, and oxidize it to create the appropriate amount of thyroxine (T4) and triiodothyronine (T3) hormones, which regulate metabolism and other vital functions in the body.

In this radioactive iodine uptake (RAIU), healthcare professionals measure how much radioactivity substance is taken up by the thyroid gland to determine its functionality.

• High RAIU: It indicates overactive thyroid gland-hyperthyroidism
• Low RAIU: It indicates an underactive thyroid gland-hypothyroidism

A week before the test, healthcare professionals may ask the patients who came to be diagnosed to avoid foods rich in iodine or medicines containing iodine. This test takes only a few minutes. During this time, the patient can be asked to swallow a small amount of radioactive iodine in liquid or capsule form. A healthcare technician places a device called a gamma probe in front of the patient's neck near the thyroid gland to measure the amount of radioactive iodine taken up by the thyroid from the bloodstream.

Measurements are typically taken 4 to 6 hours after ingesting the radioactive iodine and again at the 24-hour mark.

Imaging tests

Healthcare professionals may recommend imaging tests to diagnose and uncover the underlying cause of thyroid disease. A trained technician usually performs the following imaging tests:

• Ultrasound 
• Thyroid scan

Ultrasound: An ultrasound imaging test is performed on the thyroid to examine the thyroid nodules to find whether it is more likely to be cancerous. It usually takes around 30 minutes. During this test, a person lies on an exam table, and a technician runs a device called a transducer over the neck. The transducer sends safe, painless sound waves that are reflected off the neck to create images of the thyroid.

Thyroid scan: In addition to a radioactive iodine uptake test, a thyroid scan may also be recommended to examine the pictures of the thyroid gland to find which parts of the thyroid are taking iodine. The scan usually takes 30 minutes or less. During this time, the patient lies on a table to be examined while a special camera takes pictures of the thyroid gland to analyse its shape, size, and position. Thyroid nodules that produce an excess thyroid hormone are visible in the images. Radioactive iodine that shows up over the whole thyroid could mean the patient has Graves’ disease.

Even though only a tiny amount of radiation is required for a thyroid scan, and it is considered safe, pregnant or breastfeeding patients should not undergo this test.