Low Thyroid Symptoms Can Affect Your Heart

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It’s estimated that 20 million Americans have thyroid disease, and there are millions more who have not been diagnosed. The problem is that left untreated, low thyroid can affect your heart—causing everything from high diastolic blood pressure to heart arrhythmias, and more.

The challenge is that many people who have a thyroid imbalance can actually have normal lab values on a thyroid test. So, it’s important to stay attuned to low thyroid symptoms and work with a doctor who can help to give you an accurate diagnosis.

What Exactly Is Low Thyroid?

Your thyroid is a butterfly-shaped gland that sits at the front of your neck. The thyroid gland receives a chemical message called thyroid-stimulating hormone (TSH) from a part of your brain called the pituitary gland, which tells the thyroid how much thyroid hormone (T3 and T4) to secrete.

Low thyroid, or hypothyroidism, occurs when your thyroid gland doesn’t produce enough T3 or T4. Since thyroid hormones regulate your body’s metabolism, low thyroid can affect every cell and system in your body.

Low thyroid symptoms can include:

  • Weight gain
  • Constipation
  • Hair loss
  • Poor concentration
  • Cold intolerance
  • A slower heart rate
  • Muscle cramps
  • Dry skin

How Does a Thyroid Imbalance Affect Heart Health?

The muscles in your heart require thyroid hormones in order to contract and pump blood throughout your body. If your heart doesn’t have enough thyroid hormones on board, then the heart rate may slow too much. You are also at increased risk for peripheral vascular resistance—which reflects the amount of pressure the heart needs to pump against to circulate blood throughout your body.

There is also an association between hypothyroidism and elevated total cholesterol, LDL cholesterol, and triglycerides. Plus, low thyroid can cause insulin resistance —also known as metabolic syndrome or “pre-diabetes”—which can result in diabetes, obesity, high homocysteine levels, and high diastolic blood pressure. Together, all of these factors can lead to heart disease.

For all of these reasons, my patients with low thyroid often develop high diastolic blood pressure, bradycardia (a slow heart rate; under 60), shortness of breath (particularly during exercise), difficulties exercising, hypercholesterolemia, and elevated homocysteine.

However, I have also seen low thyroid symptoms that included low blood pressure, and not all hypothyroid patients have high cholesterol. For this reason, multiple factors must be taken into account when considering a diagnosis.

Thyroid Issues Can Be Difficult to Measure

Fatigue and constipation may be early low thyroid symptoms, even though the thyroid-stimulating hormone (TSH) level is found to be in the “normal” range of 3-5. I generally like to see a TSH of 0.5-2.5, with an ideal TSH of 1.0. If patients are symptomatic, I generally treat the thyroid when TSH is above 3.

Because TSH is not the most reliable test and TSH levels can fluctuate throughout the day, I recommend that patients also have their free T4 and free T3 levels checked. Plus, I often order testing for thyroid antibodies, known as thyroid peroxidase antibodies (TPO), as well as thyroglobulin antibodies (TG) to rule out Hashimoto’s disease, which is an autoimmune condition of the thyroid that may cause self-destruction of thyroid tissue if left untreated.

Is There a Treatment for Hypothyroidism?

You can have low thyroid for many reasons—from stress and toxicity to iodine deficiency and more. So, when it comes to hypothyroidism treatments, here are the things you want to consider.

  • Have you been exposed to toxins? I had one hypothyroid patient who recalled living on a farm where pesticides were sprayed regularly. We tried many treatments to improve thyroid function and to get her TSH within the normal range. The tide finally turned when I put her on a strict two-month medical food detoxification program to help address her past exposure to pesticides. Once we added “detoxing” her system to my interventions with thyroid and liver supportive nutrients and herbs, she started to feel like she was 20 years younger. Her TSH finally fell into the normal range. The thyroid gland is very sensitive to environmental pollutants.
  • Do you have low iodine? Iodine is the main building block for the thyroid hormone T4. In the body, the liver, kidneys, and skeletal muscles are responsible for converting T4 into its active form of T3. Since T3 is the active thyroid hormone, it is important that the body has enough co-factors like selenium, zinc, and copper to help with this conversion.
  • Have you been under stress or have impaired adrenal function? Like iodine, stress and adrenal function are also involved in the conversion of T4 to T3. In the presence of high cortisol, T4 can be converted to the inactive hormone reverse T3 (rT3) leaving less active T3 available to act on your cells. You may want to ask your doctor about doing an adrenal stress index test, which measures cortisol levels throughout the day and can provide information about adrenal gland function.
  • Are you low on iron? Since many symptoms of hypothyroidism are similar to the symptoms caused by iron deficiency anemia, it is important to rule out low iron levels. Moreover, hypothyroidism can cause low stomach acid levels, leading to poor absorption of nutrients including iron and vitamin B12. Low iron in the body also decreases the conversion of T4 to T3 and can elevate TSH levels.
  • Do you have enough vitamin D? Vitamin D deficiency is associated with the degree and severity of hypothyroidism. So, you may want to ask your doctor to check your vitamin D levels—which is something I do for all of my hypothyroid patients.
  • Is gluten affecting your thyroid? There is an increased correlation between those with autoimmune thyroid disease like Hashimoto’s, and celiac disease (an autoimmune condition where the ingestion of gluten causes damage to the cells of the small intestine). Therefore, it is important to screen for celiac disease and gluten intolerance.

There are also nutraceuticals and herbal medicines to help support the thyroid gland:

  • Ashwagandha: helps conversion of T4 to T3 and is an adrenal tonic (400 mg daily).
  • Selenium: assists in the production of T4. To get selenium, you can supplement with selenomethionine (200 mcg daily), or eat Brazil nuts.
  • L-Tyrosine: supports the production of T4 (250 mg daily).

Thyroid glandulars are also very powerful medicines and require close supervision by your doctor.

Dr. Drew Sinatra

Meet Dr. Drew Sinatra

Dr. Drew Sinatra is a board-certified naturopathic doctor and self-described “health detective” with a passion for promoting natural healing, wellness, and improving quality of life by addressing the root cause of illness in patients of all ages. His vibrant practice focuses on treating the whole person (mind, body, and spirit) and finding missed connections between symptoms and health issues that are often overlooked by conventional medicine.

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