Hashimoto’s thyroiditis is a chronic autoimmune disorder where the body’s immune system mistakenly attacks the thyroid gland, which is located at the base of the neck. This gradual immune assault leads to inflammation and damage, ultimately impairing the gland’s ability to produce enough thyroid hormones, resulting in hypothyroidism. Many individuals living with this condition report experiencing heart palpitations, a sensation that the heart is racing, pounding, or skipping a beat. Understanding the connection between this autoimmune disease and these cardiac symptoms requires examining the role of thyroid hormones in the body. This article clarifies the mechanisms by which Hashimoto’s disease and its treatment can lead to palpitations.
Understanding Hashimoto’s and Thyroid Hormone Function
The thyroid gland is a central component of the endocrine system, producing two primary hormones, thyroxine (T4) and triiodothyronine (T3), that regulate the body’s overall metabolism. These hormones influence the rate at which cells convert food into energy, affecting nearly every organ system, including the heart. T4 is the major form released into the bloodstream, but it must be converted into the more biologically active T3 in various tissues to exert its full effect.
Hashimoto’s disease disrupts this vital hormonal balance by causing the body’s immune cells to slowly destroy the thyroid tissue. This damage leads to an insufficient supply of T4 and T3, a condition known as hypothyroidism. However, during the initial stages of the autoimmune attack, the damaged thyroid cells can sometimes release a temporary surge of stored hormone into the bloodstream, causing brief periods of hyperthyroidism before the gland eventually fails.
The Direct Link Between Thyroid Imbalance and Palpitations
Thyroid hormones exert a profound and direct influence on the cardiovascular system, controlling both the heart rate and the force of contraction. The heart is a major target organ for T3, which acts by regulating the expression of genes that code for key cardiac proteins. Specifically, T3 increases the number of beta-adrenergic receptors on heart muscle cells, making the heart more sensitive to circulating catecholamines, such as adrenaline.
The palpitations experienced by people with Hashimoto’s are typically linked to states of thyroid hormone excess, which can occur during those brief, initial fluctuations of the disease. When excess thyroid hormone is present, this enhanced sensitivity to adrenaline causes the heart to beat faster and with greater force, resulting in tachycardia and the perceived sensation of a palpitation. This accelerated heart activity can also predispose individuals to specific rhythm disturbances, such as atrial fibrillation.
While hyperthyroidism is the more common link to palpitations, severe, long-term hypothyroidism can also affect heart function. Low thyroid hormone levels lead to a decrease in cardiac output and a slower-than-normal heart rate, known as bradycardia. Although less common as a direct cause of a fluttering feeling, the changes in heart function associated with severe hypothyroidism can still be perceived by some individuals as an irregular or noticeable heartbeat.
Palpitations Caused by Treatment Adjustments
Palpitations in individuals with Hashimoto’s are often related to the treatment rather than the disease itself. The standard management for hypothyroidism involves hormone replacement therapy, most commonly using the synthetic T4 medication Levothyroxine. This medication is designed to restore thyroid hormone levels to a normal range, a state referred to as euthyroidism.
If the dosage of Levothyroxine is too high, it leads to a state of iatrogenic hyperthyroidism, meaning the excess hormone is induced by the medical treatment. The symptoms of this over-replacement mirror those of natural hyperthyroidism, including an accelerated heart rate, increased force of contraction, anxiety, and tremors.
Regular monitoring of thyroid-stimulating hormone (TSH) levels is crucial to prevent this over-replacement. TSH, a hormone released by the pituitary gland, acts as the primary feedback signal for thyroid function. If blood tests show a TSH level that is too suppressed, the Levothyroxine dose is likely too high and must be adjusted downward by a healthcare provider to alleviate the cardiac symptoms.
When to Seek Medical Attention and Management Strategies
Palpitations related to thyroid imbalance should always be evaluated by a medical professional. Palpitations accompanied by concerning symptoms require immediate medical attention, as they may signal a more serious cardiac event. Emergency care is warranted if palpitations are experienced alongside chest pain, severe shortness of breath, dizziness, or fainting.
The primary management strategy for thyroid-related palpitations is to optimize the thyroid hormone replacement dosage. This involves close collaboration with an endocrinologist or primary care physician to titrate the Levothyroxine dose until TSH and free T4 levels are consistently within the optimal therapeutic range. Once hormone levels are stabilized, the heart’s hyperactivity typically resolves, and the palpitations subside.
Palpitations can also have non-thyroid causes, such as high caffeine intake, stress, anxiety, or underlying anemia. A comprehensive approach involves ruling out these other potential triggers through blood work and possibly a cardiac evaluation, such as an electrocardiogram or a Holter monitor. Lifestyle adjustments, including reducing stimulants and employing stress-reduction techniques, can also serve as effective secondary management tools.