Hypertension (high blood pressure) is one of the common effects of thyroid cancer. If you have or have had thyroid cancer, there is a lasting risk of developing hypertension even after the cancer is fully treated.
The long-term effects of high blood pressure produce a number of health problems over time, including increased strokes, heart attacks, kidney disease, and dementia.
Thyroid Cancer and Hypertension
All thyroid cancers can increase or decrease the production of your thyroid hormones. Cancer can be associated with symptoms or the development of hyperthyroidism (overactivity of thyroid hormones) more than with hypothyroidism (under activity of thyroid hormones).
Hyperthyroidism results in increased metabolism and usually causes increased blood pressure. In contrast, hypothyroidism is usually associated with normal blood pressure, but it can cause low blood pressure or high blood pressure.
The reasons are complicated: Thyroid hormones act directly on blood vessels throughout the body to reduce contractility (make them less flexible), which increases blood pressure. However, blood vessels can develop increased or decreased sensitivity to thyroid hormones, making the response to altered thyroid hormone levels somewhat variable.
Keep in mind, a majority of patients diagnosed with thyroid cancer have neither hyperthyroidism or hypothyroidism.
Often, a nodule, growth, or goiter can be the first sign of thyroid cancer. Other symptoms include weight changes, fatigue, or agitation. Rarely, however, it’s unexplained hypertension, that prompts a thyroid function evaluation and may lead to a diagnosis of thyroid cancer. This is especially true if high blood pressure begins at an unusually young age or is not easily managed with medication.
The Impact of Thyroid Cancer Treatment
There are a number of treatment strategies used for thyroid cancer, including chemotherapy, radiation, surgery, and thyroid replacement medications after treatment. These approaches, while necessary, can independently induce hypertension.
Several of the chemotherapeutic medications used for thyroid cancer have been shown to cause high blood pressure. Pazopanib, cabozantinib, and vandetanib are all classified as tyrosine kinase inhibitors, a common type of chemotherapy, and they have all been linked to hypertension when used for the treatment of thyroid cancer. The exact mechanism of this effect is not known.
Surgical treatment for thyroid cancer has also been associated with hypertension. There are several known reasons for this reaction. Removal of the thyroid gland stimulates an increase in thyroid stimulating hormone (TSH), which can cause overproduction of thyroid hormones from the remaining thyroid gland. In some instances, a condition called thyroid storm can occur, which is a severe rise in thyroid hormones that can cause a sudden increase in metabolism and blood pressure.
Thyroid Replacement Medications
After recovery from thyroid cancer, you may need to take thyroid hormone replacement medications, especially if you have had surgery or radiation. Generally, thyroid hormone replacement is aimed at achieving optimal thyroid function. However, excess thyroid hormone replacement can induce hypertension, while inadequate levels of thyroid hormone replacement can cause your body to overcompensate, possibly producing hormones (such as adrenal hormones) that trigger hypertension.
Over time, your thyroid replacement medication can be adjusted so that you can get just the right amount of thyroid hormone.
Recognizing and Treating Hypertension
Hypertension does not usually cause any symptoms unless there is a hypertensive crisis, which is rare. Given this, it’s unlikely you’ll notice any warning signs. Many, in fact, are surprised to learn of the diagnosis after their healthcare provider uses a blood pressure cuff during a physical examination as a matter of routine.
Your healthcare provider may also recommend that you monitor yourself at home, especially if you have other hypertension risk factors. You can purchase a blood pressure cuff for self-checks or visit a local pharmacy or community center, which may have one available for you to use.
If you are diagnosed with hypertension, there are effective prescription medications that can control your blood pressure.
Because thyroid disease, thyroid treatment, and thyroid replacement medications can all interfere with your blood pressure, you may need the dose of your blood pressure medication adjusted as your thyroid function changes during your cancer treatment and after your recovery.
Tracking your blood pressure and strategically timing your hypertension medication are helpful strategies for ensuring you stay in your goal blood pressure range.
If you have thyroid cancer, you are at an increased risk of developing hypertension even after you've been successfully treated. People who were 40 or older when diagnosed with thyroid cancer, for example, are about 46% more likely to develop hypertension.
Uncontrolled hypertension can put you at greater risk for serious conditions like coronary artery disease, stroke, heart failure, and dementia. This is why it's important to make sure you have your blood pressure checked regularly. If you do have high blood pressure, make sure to work with your healthcare provider to control it.
A Word From Verywell
Hypertension is very common, but if you have or have had thyroid cancer, you have an even greater chance of developing the condition.
If you are recovering from thyroid cancer, it is a good idea to familiarize yourself with the most updated recommendations for your target blood pressure so that you can let your healthcare provider know right away if your blood pressure changes.