The Relationship Between Blood Pressure and Thyroid

The dangers of high blood pressure are well-known yet this condition can often go undetected due to a lack of symptoms. High blood pressure, or hypertension, isn’t always a standalone health concern either. Secondary hypertension is fairly common and can occur as symptom alongside many health conditions, such as thyroid disorders.

Thyroid disorders are surprisingly common yet often go undiagnosed. The reason for this is not clear, but could be a combination of people not knowing common symptoms of thyroid disorders and doctors not testing for these issues often enough. Without treatment a thyroid disorder will only worsen over time, and if combined with hypertension can lead to severe health problems.

Thankfully more studies are being done on the link between hypertension and the thyroid, as the connection between the two was fairly unknown until recently. Early recognition of an ill thyroid gland and sudden high blood pressure is important for faster patient recovery.

Which Thyroid Disorders are Associated with Hypertension?

When hypertension is present in a patient with a thyroid abnormality it is often the thyroid gland that started this problem.

There are three types of thyroid conditions associated with secondary hypertension:

  • Hypothyroidism – Too little thyroid hormone being produced
  • Hyperthyroidism – Too much thyroid hormone being produced
  • Hyperparathyroidism – Overactive parathyroid glands

Hypothyroidism is the most common thyroid disorder, affecting roughly 20 million Americans. It was once believed that an underactive thyroid gland would actually cause low blood pressure but studies have shown otherwise. Hypertension occurs in those with hypothyroidism because of how the thyroid hormones affects blood vessel and arterial constriction. Healthy thyroid hormones levels have an important dilating effect on the vascular system. When this hormone is suddenly not being produced at adequate levels, blood pressure rises because of vasoconstriction.

Hyperthyroidism is more rare, with only about 2.5 million Americans believed to have this disorder. While cases of hypertension are greater in patients with hypothyroidism, this is due to a much higher number of people having this disorder. When it comes to hyperthyroidism patients are actually more likely to develop secondary hypertension. A spike in too much of the thyroid hormone can lead to increased blood pressure. Interestingly, hyperthyroidism is more likely to cause isolated systolic hypertension. Those with this type of hypertension will notice that only the top number in their blood pressure reading spikes.

Hyperparathyroidism is more rare than the two main thyroid disorders but still has a correlation to hypertension. The parathyroid glands are actually four very small glands located on the back of the thyroid gland. These tiny but powerful glands produce the parathyroid hormone which controls calcium in the blood. Hyperparathyroidism occurs when these glands malfunction and allow too much calcium into the bloodstream. Too much calcium leads to higher blood pressure, which will develop into a disorder when it happens consistently.

Determining if you have a thyroid disorder can be done through a blood test. While you can get an idea of whether you might have hypo or hyperthyroidism by comparing common symptoms, the only way to know for sure is with lab work. It is a good idea for those that are more apt to developing thyroid conditions to regularly check in with their doctor so a potential gland issues will be caught more quickly. This includes those with a family history of thyroid disorders, overweight or obese people, and women who have entered menopause.

What is Secondary Hypertension?

Secondary hypertension is less common than primary hypertension and the most common high blood pressure disorder associated with the thyroid. Secondary hypertension is simply high blood pressure that is a symptom of another health issue. This type of hypertension is fortunately more easily identified and treated compared to more complex primary hypertension.

Hypertension of either type can lead to serious health consequences, made even more dangerous since secondary hypertension can show few symptoms. Some common signs of high blood pressure being secondary hypertension include:

  • Resistance to high blood pressure medication
  • Unusually high blood pressure
  • High blood pressure medication gradually losing its effect
  • Rapid development of hypertension

Unlike primary hypertension, those with secondary hypertension may have no history of high blood pressure and could otherwise be fit or at a health weight. Essentially secondary hypertension cause occur even when a patient’s lifestyle wouldn’t normally prompt a blood pressure issue.

It can be argued that secondary hypertension can be more of an issue than primary. The reason for this is that the hypertension will not only worsen the original health problem, but it also can cause it’s own negative side-effects. This can make treatment more difficult. Left untreated secondary hypertension can cause:

  • Atherosclerosis (hardening and thickening of the arteries)
  • Aneurysms
  • Kidney Damage
  • Loss of Vision
  • Heart Failure

Untreated hypertension can also induce further metabolic disorders which weakens the body, increasing the chances of serious health problems like diabetes. Even if the hypertension hasn’t yet reached a threatening high, consistent hypertension will begin to affect your daily life by harming memory and brain function. The risks of heart disease and even stroke make secondary hypertension just as serious as primary.

Treating secondary hypertension will often not only control the high blood pressure concern, but aid in alleviating the underlying disorder that originally caused it to happen. If a thyroid disorder is the cause of your high blood pressure, you won’t be able to completely solve this problem unless both issues are treated. In some cases just getting on medication for the thyroid will bring blood pressure back down to a healthy level without further treatment.

How are Thyroid Disorders with Secondary Hypertension Treated?

If you suspect a thyroid disorder you should schedule an appointment with your doctor immediately. As mentioned above a blood test is the only way to determine if you have a disorder. There are actually four different blood tests to determine a thyroid disorder, which include:

  • T3
  • T3RU
  • T4
  • TSH

Of these four the first test most doctors call for is the T4 or the TSH. Both tests can be used to detect either of the thyroid disorders. The T4 test will show high for hyperthyroidism and low for primary or secondary hypothyroidism. The TSH blood panel will show the opposite – low for hyperthyroidism, high for primary hypothyroidism and low for secondary hypothyroidism.

The names of these tests, such as T3 and T4, are named so after the thyroid hormone. There are two thyroid hormones present in the body, triiodothyronine (T3) and thyroxine (T4). Typically if a thyroid test comes back with abnormal or unclear results, your doctor may do another blood test for further lab work.

If you are experience hypertension and a thyroid test comes back with an abnormal result, it is likely that your high blood pressure is secondary hypertension. Treatment of secondary hypertension will differ greatly depending on your physician and the severity of your disorder.

For example, if your doctor determines that your secondary hypertension isn’t severe and it stemming from your thyroid, you may only need to be put on thyroid medication to solve both issues. On the other hand, if you doctor finds you have a severe thyroid condition and hypertension, typically both health issues will need to be tackled at once. This may include a treatment plan of both thyroid medication and high blood pressure medication.

If your doctor determines that you have hyperparathyroidism treatment will differ from hypo or hyperthyroidism. Instead of a T4 medication or other treatment your doctor may instead use hormone replacement therapy, bisphosphonates or calcimimetics. Sometimes surgery is required. Those with secondary hypertension and hyperparathyroidism may be more likely to need to go on a blood pressure medication until the hyperparathyroidism is under control.

Secondary hypertension and thyroid disorders can have dangerous effects on health when left ignored, but thankfully the average person with these issues can have both cured with medication and physician supervision. Those with a family history of hypertension should pay special attention if they suspect a thyroid issue.


Leave a Reply