Ongoing research confirms what many people with hypothyroidism already know. When your thyroid is low, your heart slows down which leaves you feeling breathless and fatigued.
Studies show the thyroid hormones target the heart to keep it working in tip-top shape. These hormones influence blood pressure, cholesterol levels, even the force and speed of each heartbeat. As a result, thyroid dysfunction increases risk of developing serious cardiovascular problems.
The Link Between Hypothyroidism And Heart Health
If you have been diagnosed with hypothyroidism it’s important to pay special attention to your cardiovascular health. Here’s a list of the most common cardiac symptoms associated with hypothyroidism:
- slow pulse rate (bradycardia).
- heart palpitations.
- low blood pressure.
- cold intolerance.
- poor circulation.
- ongoing fatigue.
What Is Bradycardia?
The resting heart rate of a healthy person is usually between 60 to 100 beats per minute. Bradycardia is the medical term to describe a slow pulse rate.
Bradycardia is defined as a resting heart rate of 60 beats per minute or less.
This heart disorder is a common finding in individuals with hypothyroidism. In fact, it may be the symptom that leads to a diagnosis of an under active thyroid.
The reduced ability of the heart to pump blood efficiently places far greater strain on the heart. It also reduces the flow of oxygen and nutrients to the organs and tissues.
Low T3 Is An Important Piece Of The Puzzle
It’s well established that the thyroid hormones, particularly triiodothyronine (T3) act on almost every cell and organ in the body. This includes the heart where this potent thyroid hormone is highly active.
T3 is vital to safeguard healthy cardiac function and when T3 is inadequate, the heart suffers.
Low free T3 is a common finding in individuals with heart disorders. T3 may be low due to diminished production of the thyroid hormones, impaired conversion of thyroxine (T4) to T3, or increased conversion of T4 to the inactive form of T3 known as reverse T3 (rT3).
Is Your Thyroid Health Putting You At Risk?
Hypothyroidism is associated with raised total cholesterol and puts you at greater risk of developing heart disease.
If you have been told your cholesterol is high and you have symptoms of hypothyroidism speak to your doctor about getting your thyroid checked.
Investigating The Thyroid, Heart Health Connection
These are the most tests used to investigate both thyroid and heart health.
Physical examination of the cardiovascular system
- Blood pressure (systolic and diastolic)
- Pulse rate (check above 60 beats per minute)
- Electrocardiography (ECG), echocardiogram and cardiac magnetic resonance imaging (MRI)
Physical examination of the thyroid
- Thyroid ultrasound
- Inspection of the thyroid to check for swelling + tenderness
Thyroid function test; TSH, free T4, free T3, thyroid antibodies and reverse T3.
Cardiac function tests:
- Cholesterol panel; Total cholesterol, HDL, LDL and VLDL.
- Glucose tolerance test
- C-reactive protein (CRP)
- Full blood count (FBC)
- Liver function test (LFT)
The Good News?
In many cases the risk of developing a serious cardiovascular disorder can be minimised when an underlying thyroid problem is recognised and properly treated.
It also turns out the heart has remarkable regenerative abilities when healthy levels of the thyroid hormones are restored, particularly T3.
Danzi S, Klein I. Thyroid hormone and the cardiovascular system. Med Clin North Am. 2012 Mar;96(2):257-68.
Mourouzis I, Politi E, Pantos C. Thyroid Hormone and Tissue Repair: New Tricks for an Old Hormone? J Thyroid Res. 2013;2013:312104.
Pantos C, Mourouzis I, Cokkinos DV. Thyroid hormone and cardiac repair/regeneration: from Prometheus myth to reality? Can J Physiol Pharmacol. 2012 Aug;90(8):977-87.
Udovcic M, Pena RH, Patham B, Tabatabai L, Kansara A. Hypothyroidism and the Heart. Methodist Debakey Cardiovasc J. 2017;13(2):55–59.