The thyroid gland is an endocrine gland in the front of the neck, the shape of which resembles a butterfly. It secretes hormones that control metabolism, energy, temperature, and heart rate. Autoimmune thyroid diseases such as Hashimoto and Graves' can occur when the immune system attacks the thyroid gland.
Both diseases are related to the immune system, but affect the activity of the thyroid in separate ways. Both Hashimoto's and Graves' tend to manifest as an underactive or overactive thyroid, respectively. Patients must be aware of the difference between these conditions; otherwise, they are not able to recognise symptoms and seek medical advice. For cases that are recommended for additional diagnostic tests and/or nuclear medicine services, at Molecular Diagnostics and Therapy, under the care of Dr. Nikunj Jain, the patient can obtain advice on the thyroid-related tests to be performed and on the types of services that can be provided through nuclear medicine.
What Is Hashimoto’s Disease?
Hashimoto's disease, also known as Hashimoto's thyroiditis, is a disease caused by the immune system attacking the thyroid gland. This may result in damage to the thyroid tissue over time and less efficient production of adequate hormones. This leads to hypothyroidism (a thyroid gland that is not working normally). But some individuals may be a Hashimoto's "carrier" for several years before experiencing any symptoms. Symptoms are tiredness, increased weight gain, sensitivity to colds, constipation, dry skin, thinning hair, and problems with concentration. In addition, some patients may develop an enlarged thyroid ("goitre"). Thyroid function tests and antibody tests of the thyroid are often used to take a look at suspected Hashimoto's.
What Is Graves’ Disease?
Graves' is a second type of autoimmune thyroid disorder that typically results in the thyroid producing high levels of hormones. This results in an overactive thyroid (hyperthyroidism). Graves' disease is caused when the body's immune system produces antibodies that cause the thyroid to secrete thyroid hormones beyond normal levels. These symptoms may include sudden weight loss, increased heart rate, profuse sweating, uneasiness, shaking/lacking control of hands, restlessness, trouble sleeping, or temperature sensitivity. Some patients also have to urinate frequently or lose muscle mass. Some individuals may experience dryness, irritation, bulging or swelling of the eyes due to Graves' disease. Symptoms associated with Graves' eye disease need proper doctor's assessment.
Hashimoto’s Disease vs. Graves’ Disease
Although both conditions are autoimmune disorders, several important differences help doctors distinguish between them.
1. Effect on Thyroid Hormones
The major difference is that each of the conditions alters the production of hormones. In Hashimoto's, the thyroid gland over time starts to produce fewer hormones or does not produce enough, and is often accompanied by low thyroid hormone levels and elevated TSH. With Graves' disease, the thyroid becomes overstimulated (hyperthyroid) and creates more hormones. This, in turn, often leads to high thyroid hormone levels and low TSH levels. These can be different in both early phases of either of these diseases.
2. Common Symptoms
When symptoms of Hashimoto's are associated with a slower metabolism, it is typically a problem with the thyroid. Patients can be tired, constipated, gain weight, or get cold. Graves’ disease gives rise to symptoms of being overactive. Some of these symptoms can be weight loss with an apparently increased appetite, lots of heartbeats, sweating, nervousness, and intolerance of heat. Both can lead to alterations in the functioning of the menstrual cycle, mood, and energy level. Symptoms can overlap or be misleading, so blood tests are needed to tell the conditions apart.
3. Causes and Risk Factors
Both are autoimmune, but the immune attack works differently in each. Autoimmune thyroid disease may run in the family and have some genes that make a person more likely to develop it. Other factors such as gender, exposure to the environment, and age also play a role. They can affect both men and women, but are more common in women. It's not always clear why some individuals develop Hashimoto's disease, and why others develop Graves' disease.
4. Thyroid Antibodies
An antibody blood test can help differentiate between these disorders. Thyroid peroxidase antibodies and sometimes thyroglobulin antibodies are found in patients with Hashimoto's disease. Thyroid-stimulating antibodies that interact with thyroid-stimulating hormone receptors are involved in Graves' disease. They are antibodies that act on the thyroid, causing excessive production of thyroid hormones. Thyroid antibody results should be used in conjunction with the thyroid function tests, any clinical symptoms, and history. However, it may not be enough just to have a positive antibody test to complete the clinical picture.
5. Effects on the Eyes
Graves' disease is more closely related to issues with the eyes. Some patients get Graves' eye disease, which may result in irritated eyes, puffiness, sensitivity to light, double vision, or bulging eyes. Eye problems are not common with Hashimoto's disease. But someone who has either of these diseases can complain of overall eye pain for any other reason. If you experience double vision, any level of eye pain, and/or vision changes, you should seek immediate medical evaluation.
How Are Hashimoto’s Disease and Graves’ Disease Diagnosed?
Doctors diagnose autoimmune thyroid conditions using a combination of medical history, physical examination, and laboratory tests.
Thyroid Function Tests
A TSH test is commonly used to assess thyroid function. Free T4 and, when appropriate, T3 tests provide additional information about hormone levels. In Hashimoto’s disease with established hypothyroidism, TSH is usually high and free T4 is low. In Graves’ disease, TSH is usually low, while free T4 and/or T3 are elevated.
Thyroid Antibody Tests
TPOAb and TgAb tests may support a diagnosis of Hashimoto’s disease. TRAb testing can help identify Graves’ disease, particularly when the diagnosis is uncertain.
Thyroid Imaging
Doctors might order a thyroid ultrasound if they suspect the gland is enlarged, is formed in a certain way, and/or has nodules. For some people, thyroid uptake (or thyroid scintigraphy) can be used to provide information about the activity of the thyroid gland and to distinguish Graves' disease from other types of hyperthyroidism. These investigations involve using a small dose of radioactive tracer but are not suitable for all patients. Depending on the clinical situation, the choice of imaging is weighed. Radioactive iodine uptake tests should also largely be avoided during pregnancy, and special medical advice is needed to use this procedure for women who are breastfeeding.
How Are These Conditions Treated?
Treatment depends on the diagnosis, thyroid hormone levels, symptoms, and the patient's overall health.
Treatment for Hashimoto’s Disease
If Hashimoto's disease leads to chronic hypothyroidism, doctors usually prescribe synthetic thyroid hormone (levothyroxine), which can make up for the hormone that the body isn't producing enough of. Doses are modified depending on blood (laboratory) tests and clinical response. Hormone level monitoring is essential to make sure that hormone levels are in the desired range. Those who have thyroid antibodies but not signs of thyroid disease do not require the immediate use of drugs. Instead, their doctor may recommend they have them checked on a regular basis.
Treatment for Graves’ Disease
Graves’ disease can be treated with antithyroid drugs, which reduce thyroid hormone production. Sometimes, beta-blockers are used to treat symptoms like fast heartbeat and tremor for only a short while. Depending upon the patient's circumstances, treatment with radioactive iodine or thyroid surgery is considered. The radioactive iodine lessens the activity of the thyroid, but may lead to hypothyroidism, and so treatment with thyroid hormone may be necessary for life. Radioactive iodine therapy is not done during pregnancy or breastfeeding. If a treatment is to be undertaken, then it is best to consult a suitable specialist.
Can Hashimoto’s Disease Turn Into Graves’ Disease?
One should not typically develop into the other, and Hashimoto's is a different autoimmune condition than Graves'. Thyroid function can, however, vary with time, and in unusual instances a person could have characteristics of both conditions at various points in time. Rather than take variations of thyroid blood tests for a given condition for granted, new symptoms or changes in blood tests should be evaluated by a health care provider.
When Should You Consult a Doctor?
If fatigue is a recurring complaint, there are other changes to your body that you may notice, such as an irregular heartbeat, weight gain or loss, a swollen neck, neck pain, palpitations, or excessive sensitivity to temperature, particularly cold or heat. If this occurs, seek medical advice, as it is likely you are having some thyroid-related symptoms. Hormone assessments can be used to help determine hormone imbalance and treatment options if necessary. If you have worsening chest pain, trouble breathing, dizziness, or blurring in your vision, get immediate medical help.
Conclusion
Graves’ disease and Hashimoto's thyroiditis are autoimmune disorders, and typically they have opposite effects on thyroid hormone production. A common consequence of Hashimoto's disease is an underactive thyroid or hypothyroidism, while an overactive thyroid or hyperthyroidism is a typical result of Graves' disease. Doctors can use blood tests, thyroid antibody tests, and certain imaging tests to determine the cause of the imbalance and select appropriate treatment. Symptoms can overlap, so testing is needed for an accurate diagnosis.
Dr Nikunj Jain, Co-Founder and Head of Nuclear Medicine at Molecular Diagnostics and Therapy, is connected with the nuclear medicine services of the centre. If someone is interested in information about thyroid imaging and the investigations that are available, they should ask for help from an appropriate health care provider who can help them understand which investigation may be suitable for the patient they are looking after.