Can You Have Both Graves' and Hashimoto's?



“Can a person have both types of thyroid disease? I am on 400 mcg QD of thyroid meds now. The doctor told me I have both Graves’ and Hashimoto’s. Can this be true? Are there any questions I should ask?”

-Thyroid Disease


This is a common question about two separate yet similar autoimmune thyroid diseases.

In both diseases, antibodies influence your thyroid. Graves’ disease is characterized by thyroid stimulating immunoglobulin (TSI) antibodies, which make your thyroid overproduce thyroid hormone, causing hyperthyroidism.

Hashimoto’s thyroiditis is characterized by thyroid peroxidase (TPO) antibodies, which block your thyroid’s ability to produce thyroid hormone and progressively destroy your thyroid gland, causing hypothyroidism.

You can have both Hashimoto’s thyroiditis and Graves’ disease — diagnosed by positive antibodies, and in some cases, confirmed by imaging and biopsy tests —  at the same time. Simultaneously having both Graves’ stimulating and Hashimoto’s blocking antibodies means that your balance of antibodies at any time determines your thyroid function. This state is sometimes called Hashitoxicosis.

The confusion is that Hashimoto’s typically causes hypothyroidism, and Graves’ disease typically causes hyperthyroidism. You can’t be both hypothyroid and hyperthyroid at the same time. You can, however, fluctuate between Graves’ disease and Hashimoto’s, or develop one disease after the other.

Developing Hashimoto’s thyroiditis after Graves’ disease is, in fact, quite common. According to research, approximately 15 to 20 percent of people with Graves' disease develop spontaneous hypothyroidism from Hashimoto's thyroiditis. Developing Graves’ disease after Hashimoto’s is quite rare, but it is possible.

Some important questions to ask your healthcare provider:

  1. The first and most important question to ask is how your diagnosis of both Graves’ disease and Hashimoto’s thyroiditis was confirmed. If you have Hashimoto’s — the more prevalent autoimmune thyroid disease — it’s common to have periods when your thyroid becomes overactive. These periods of hyperthyroidism may be misdiagnosed as Graves' disease when they are actually a symptom of Hashimoto’s. If this is the situation, you have Hashimoto’s … but not Graves’ disease.
  1. If you are confirmed to have both Graves' disease and Hashimoto's, the second important question is whether doctor has identified a potential cause. “Swinging” between symptoms of both Hashimoto’s and Graves’ is sometimes triggered by interferon therapy for hepatitis C.

  2. The third question focuses on your treatment. Because hyperthyroidism and hypothyroidism don’t occur simultaneously, your treatment will target the current state of your thyroid gland. That means you’ll be prescribed thyroid hormone replacement medication if you’re hypothyroid, and your doctor will treat you with antithyroid drugs or radioactive iodine if you’re hyperthyroid. Interestingly, according to research published in the journal Endocrinology, if you have Graves’ disease and Hashimoto’s thyroiditis, you may not even need treatment. It is possible in some cases for your Hashimoto’s to become extensive and active enough to “cure the hyperthyroidism with resultant hypothyroidism.”

  1. Finally, because your thyroid function can fluctuate, ask your endocrinologist how often you should be retested and monitored, so that your treatment can be adjusted when your thyroid function or antibody balance changes.

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You should know: The answer above provides general health information that is not intended to replace medical advice or treatment recommendations from a qualified healthcare professional.

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Answered by Mary Shomon