Having a thyroid problem may impact energy, heart rate, body weight, and overall health. Graves' disease and thyroiditis are two diseases that can alter the level of thyroid hormones, but they alter the thyroid gland in different ways. A thyroid scan helps your doctor know how the thyroid is working and can shed light on patterns that aid in diagnosis. At Molecular Diagnostics and Therapy, Dr. Nikunj Jain, Co-Founder and Head of Nuclear Medicine, brings over 18 years of experience in nuclear medicine, including the evaluation of thyroid disorders and the role of thyroid imaging in diagnosis. What Is a Thyroid Scan? A thyroid scan is a nuclear medicine imaging procedure that assists in the assessment of thyroid structure and function. The thyroid is a butterfly-shaped gland in the front of the neck. It makes hormones to help control metabolism, temperature, and energy expenditure. While the scan is collecting data, a tiny amount of a radioactive tracer is given into a vein or swallowed as a capsule or liquid. A special camera is used to measure how well the thyroid has taken up the tracer and makes images of the thyroid activity. The scan can allow the doctor to see if the thyroid is normal, is using up the tracer more or less rapidly, or is not using it at all. The results of these tests are also considered in conjunction with the clinical symptoms and blood tests. What Is Graves’ Disease? Graves' disease is a result of an autoimmune condition where the immune system causes the thyroid gland to make too much thyroid hormone. This condition can be a cause of hyperthyroidism, or an overactive thyroid. Symptoms include heart rate issues such as a rapid heartbeat, weight loss, sweating, anxiety, trembling hands, and heat intolerance. Additional indications can also include an itchy, red, or swollen eye or eyes. Blood tests (thyroid hormones and TSH) confirm hyperthyroidism, and antibody tests help show whether Graves’ disease is the cause. In cases where the cause of hyperthyroidism is not established, a thyroid scan can offer extra details as to how the gland is functioning. How Can a Thyroid Scan Help Diagnose Graves’ Disease? In Graves' disease, there is usually excess hormones produced throughout the thyroid gland. This causes a diffusely elevated thyroid uptake that may be observed on the thyroid uptake scan. This pattern means that the thyroid gland is producing thyroid hormones. When combined with thyroid function tests and in conjunction with other appropriate antibody markers, the scan results can help confirm the diagnosis of Graves' disease.
For doctors who want to distinguish Graves' disease from other overactive thyroid conditions, a thyroid scan might be especially helpful. Not everyone with hyperthyroidism needs a thyroid scan. The doctor decides based on blood tests, symptoms, and the clinical picture.
How Can a Thyroid Scan Help Diagnose Thyroiditis?
In many cases, during the phase of elevated thyroid hormone levels, thyroiditis does not result in elevated tracer uptake, as was the case in Graves' disease. This is because the raised levels of hormones can be the result of hormones being released from storage rather than newly made.
Therefore, a thyroid scan that showed little uptake could assist doctors in differentiating thyroiditis from Graves' disease, which would have higher uptake of radioactivity in the entire thyroid. Low uptake is not unique to thyroiditis, though. Recent iodine exposure and some medications can also lower tracer uptake. Doctors use the scan to evaluate it along with the blood test, symptoms, medications used, and other results. Graves’ Disease vs Thyroiditis: What Does a Thyroid Scan Show? The key difference on the scan is the uptake pattern. In most cases of Graves' disease, the thyroid gland produces an excessive amount of its hormones, resulting in increased tracer uptake in the gland. During the hormone-release phase of thyroiditis, uptake typically decreases because stored hormone enters the bloodstream rather than being newly produced.
This difference can help physicians determine the cause of abnormal thyroid hormone levels. But not all thyroid scans help to differentiate. Blood tests, thyroid antibody testing, and the evaluation of the clinical exam are still valuable in the diagnostic process. Conclusion Accurate thyroid evaluation involves understanding both hormone levels and how the thyroid gland functions. A thyroid scan can provide useful information when a doctor needs to distinguish conditions such as Graves’ disease and thyroiditis. Under the guidance of Dr. Nikunj Jain, Co-Founder and Head of Nuclear Medicine at Molecular Diagnostics and Therapy, patients can receive expert guidance on thyroid imaging and related diagnostic evaluations based on their symptoms and clinical needs.