By Dr Alexander Tan Tong Boon and Dr Mohd Kamal Mohd Arshad
Sometimes, the smallest of things can affect a much larger structure.
Take the thyroid gland, for example: a butterfly-shaped gland located in the front of the neck, its purpose is to secrete thyroid hormones.
These hormones play a huge role in the body’s growth development and metabolism, and also determine the rate of organ functions within the body.
However, what would happen if the thyroid gland is unable to secrete the optimal level of hormones the body needs? What would its effect on internal organs, such as the heart, be?
More or less
When there is a disorder of thyroid function, the body’s temperature, weight, bowel movement, nerves and muscles, among others, would be affected.
Depending on whether there is an excess or lack of thyroid hormones, the results would differ according to each situation.
Hyperthyroidism is the condition where the thyroid gland is overactive, producing more thyroid hormones than the body needs.
Also known as thyrotoxicosis, this causes excessive sweating, intolerance to heat and weight loss, among other signs and symptoms.
It also causes the organs of a hyperthyroid patient to work at a faster rate.
In hypothyroidism, the thyroid gland is underactive, producing insufficient thyroid hormones for the body.
Individuals who have this condition could find themselves perpetually fatigued or tired, intolerant to cold, having sore muscles and joints, and feeling bloated, apart from other signs and symptoms.
In this case, the organs in hypothyroid patients function at a slower rate.
While there are various causes to these conditions such as certain medications, the most common cause is of autoimmune origin.
In the case of hyperthyroidism, that would be Graves’ disease, while for hypothyroidism, it is Hashimoto’s disease.
The heart link
What then is the link of these disorders to the heart?
These two thyroid conditions can directly and indirectly affect the heart through the thyroid hormone receptors within the heart muscles and blood vessels.
Thyroid hormones can increase the force of the heart’s muscular contractions, as well as increase our heart rate.
These hormones are also responsible for influencing cardiac output and arterial pressure by decreasing the stiffness of the blood vessels.
They also indirectly stimulate the renin-angiotensin hormone system, which plays an important role in regulating blood volume and reabsorbing sodium into the kidneys, thus, causing an increase in blood plasma volume.
All these changes within the circulatory system would increase the heart’s work output.
Thus, any long-term increase or decrease in thyroid hormones would affect the heart, creating new cardiovascular conditions within a patient or worsening a pre-existing heart condition.
Heart symptoms in a hyperthyroid patient are more obvious and may include palpitations, chest pain upon exertion, shortness of breath and leg swelling.
Other signs include a rapid heart rate, systolic hypertension (a high upper reading for your blood pressure) and heart failure, due to impaired relaxation of the heart muscles, increased heart muscle mass and increased blood pressure in the lungs.
Due to the increased work output of a hyperthyroidic heart, it will eventually develop cardiomyopathy (chronic disease of the heart muscle) if left untreated.
The signs and symptoms for hypothyroidism are less pronounced, but similar to hyperthyroidism, as patients would also present with shortness of breath, leg swelling and chest pain upon exertion.
The associated heart signs include a slower heart rate, diastolic hypertension (a high lower reading for your blood pressure) and heart failure, caused by reduced heart contractions and impaired relaxation of the heart muscles.
Patients with a hypothyroidic heart could also present with pericardial effusion, which is an accumulation of fluid in the lining of the heart.
Hypothyroid patients have an increased risk of developing cardiovascular diseases such as coronary artery disease and stroke, due to increased LDL (bad) cholesterol, increased thickness of the carotid blood vessel and hypertension.
Reversible if caught early
While there are cases of acquiring the condition, hyperthyroidism and hypothyroidism are mostly inherited.
With that being the case, there is no way of preventing these conditions from occurring, especially if one is already predisposed to it.
Patients with pre-existing heart conditions will also find that their symptoms will worsen if they develop any thyroid disease.
However, if the condition is diagnosed early and accurately, it can be well managed.
Side effects on the heart are also still reversible at this point if the thyroid disorder is treated.
Patients who consume certain medications containing iodine, such as amiodarone, should routinely observe and discuss their symptoms with their doctors as these medications can induce thyroid problems.
Consumption of seafood may also worsen hyperthyroidism, as these foods contain iodine that will be used by the thyroid to produce more hormones.
It is also advisable for patients who are extremely hyperthyroidic to do lighter or less strenous exercises or physical activities, until their condition is under control.
Patients with an abnormally rapid heart rate, even at rest, can worsen their condition with more intense physical activity, causing a heart arrhythmia or angina.
Patients with hypothyroidism need to ensure their levothyroxine medication is taken in the morning on an empty stomach, at least half an hour before breakfast.
This medication is poorly absorbed and ideally shouldn’t be mixed with other supplements or medications.
In many cases, patients with thyroid disorders need to understand that they need to be on life-long medication in order to control the thyroid disorder.
Good lifestyle management goes hand-in-hand with medication for patients with heart disease.
By changing their lifestyle appropriately, they will reduce the impact of thyroid disease on their health.
Examples of such changes include having patients with heart failure restrict their daily fluid intake, patients with hypertension reduce their salt intake, and those with abnormally fast heart rates reduce their coffee intake.
In Malaysia, the prevalence of diagnosed hyperthyroidism and hypothyroidism, based on studies done, stands at 3.4% of the population and 2.1% respectively.
However, the real question should be: how many individuals with this condition are undiagnosed, especially with cases of heart conditions on the rise?
The implications are frightening, especially when seen in the long run.
Undiagnosed thyroid disorders can potentially develop into something far more deadly and chro-nic, by which point its effect on the heart and other organs would be irreversible.
Hence, it is prudent to get regular check-ups to ensure that one is at the optimal level of health and well-being.