Thyroid Testing: Types, Purpose, Procedure and Preparation

Thyroid disorders are highly prevalent in India, affecting an estimated 42 million individuals. These diseases are characterised by abnormal levels of thyroid hormones secreted by the thyroid gland. Doctors perform different thyroid tests to assess the thyroid gland’s functioning and ensure proper treatment for better thyroid health.

This article discusses different thyroid disorders and the tests used to diagnose them.

What is Thyroid?

Thyroid is a small endocrine gland which is found in the lower region of the neck. The purpose of the gland is to secrete hormones that regulate significant bodily functions such as energy generation, metabolism, and mood changes.

The thyroid gland releases two major hormones, triiodothyronine (T3) and thyroxine (T4). Abnormal levels of these hormones in the bloodstream cause certain medical conditions like hypothyroidism, hyperthyroidism, or thyroid cancer.

What are Thyroid Tests?

Thyroid tests are used to examine the levels of thyroid hormones in the blood. These tests offer critical insights into the functioning of the thyroid gland and detect any irregularities or imbalances in the hormone levels.

There are many types of thyroid tests classified on the basis of hormones or proteins they detect. These tests are conducted to diagnose certain thyroid diseases that include:

1. Hypothyroidism: When thyroid hormone levels are low in the blood
2. Hyperthyroidism: When thyroid hormone levels are high in the blood
3. Thyroid Cancer: When there are malignant lumps found in the neck
4. Hashimoto’s Disease: An autoimmune disease caused by very low production of thyroid hormone
5. Graves’ Disease: An autoimmune disorder in which there is too much production of thyroid hormone

What Causes Thyroid Diseases?

Some of the common thyroid causes include:     

1. A family history of thyroid disorders
2. Taking medications high in iodine
3. Medical conditions like anaemia, Turner syndrome, type 1 diabetes, or rheumatoid arthritis.
4. Being 60 years of age or above
5. Having radiation therapy on the head or neck

What are the Symptoms of Thyroid Diseases 

Different thyroid symptoms include:

1. Slower heartbeat
2. Unexplained weight gain or loss
3. Sensitivity to heat and cold
4. Sweating
5. Fatigue
6. Difficulty in sleep
7. Depression and anxiety

What are the Types of Thyroid Tests? 

Doctors prescribe different types of thyroid tests to detect thyroid diseases.

These tests include:

1. TSH Test

This test measures the Thyroid Stimulating Hormone (TSH) level in the blood. TSH is secreted by the pituitary gland found at the brain’s base. It regulates the amount of hormones released by the thyroid. A blood test for TSH detects an overactive or underactive thyroid gland.

2. T4 Test 

T4 test is used to measure the level of thyroxine hormone in the bloodstream. A high level of T4 indicates hyperthyroidism and low levels indicate hypothyroidism. In pregnant women or those using oral contraceptives, T4 levels may appear abnormal without any underlying thyroid disorder.

3. T3 Test

A blood test for T3 measures the amount of triiodothyronine hormone in the blood. A T3 test confirms the diagnosis of hyperthyroidism as sometimes the T4 levels may appear normal even when one has thyroid disease.

4. Thyroid Antibody Test 

This test measures the presence of thyroid antibodies in the body. These antibodies indicate autoimmune disorders like Hashimoto’s disease and Graves’ disease. They are made when the immune system unintentionally attacks the thyroid gland.

5. Thyroid Scan 

A thyroid scan is an imaging procedure to examine the thyroid gland using radioactive iodine. It is used to detect any increase in the shape of the thyroid and to check for thyroid nodules or lumps in the neck. A thyroid scan detects medical conditions like hyperthyroidism, hypothyroidism, goitre, or thyroid cancer.

What is the Procedure and Preparation for the Tests?

For a thyroid blood test, doctors draw a blood sample from the patient and analyse it for underlying diseases. In the case of a thyroid scan, patients have to take a radionuclide tracer in the form of a pill, liquid, or injection. The tracer releases gamma rays when it’s inside the body. After some time, a gamma camera or scanner takes pictures of the thyroid by detecting the gamma rays. The camera presents detailed images of the thyroid’s structure with the help of a computer.

To prepare for these thyroid tests, patients must inform their physician about any medications they are taking. For a thyroid scan, one may be advised to avoid foods containing iodine for a week before the procedure.

Conclusion 

Thyroid tests play a crucial role in managing overall thyroid health. A proper knowledge of these tests, along with the symptoms of underlying disorders, can lead to early detection and effective treatment.

If someone experiences symptoms of any thyroid disorder, they must consult their healthcare provider and book a thyroid test with Dr Lal PathLabs for proper diagnosis.

FAQs

1. What are different thyroid types?

Different thyroid types include hyperthyroidism, or an overactive thyroid gland, and hypothyroidism, or an underactive thyroid gland.

2. How to prepare for a thyroid scan?

For a thyroid scan, patients should avoid foods containing iodine for a week before the procedure is due.