Hypothyroidism, also known as underactive thyroid, is a condition in which the thyroid gland does not produce enough of the thyroid hormones T3 and T4. This can lead to a variety of symptoms including fatigue, weight gain, feeling cold, constipation, dry skin, and depression among others. The prevalence of hypothyroidism is estimated to be between 0.3–0.4% for overt hypothyroidism and 3–4% for subclinical hypothyroidism. Women are more likely to be affected than men, and risk increases with age.
There are many potential causes of hypothyroidism including autoimmune disease, thyroiditis, Hashimoto’s disease, surgical removal of the thyroid, radiation treatment of the thyroid, and certain medications. However, there is debate about whether stress can also be a cause of hypothyroidism. This article will examine the evidence surrounding the relationship between stress and hypothyroidism.
Can Stress Cause Hypothyroidism?
There are several ways in which stress could theoretically contribute to hypothyroidism:
Increased Inflammation
Chronic stress leads to increased inflammation in the body. Inflammation can interfere with thyroid function in several ways:
– Inflammation of thyroid gland (thyroiditis) directly impairs hormone production
– Inflammation impairs conversion of T4 to active T3 hormone
– Inflammatory cytokines inhibit thyroid stimulating hormone (TSH) receptor reducing TSH signaling
Impaired Thyroid Hormone Synthesis
The thyroid gland requires adequate nutrition and energy to produce thyroid hormones. Prolonged stress can deplete micronutrients and impair mitochondrial energy production needed for hormone synthesis.
Altered Thyroid Stimulating Hormone
Stress causes elevated cortisol levels. High cortisol can alter the hypothalamic-pituitary feedback leading to decreased TSH production from the pituitary.
Increased Immune Attack on Thyroid
Stress raises glucocorticoids like cortisol. This shifts the balance of Th1/Th2 immunity and allows autoimmune Th1 cells to more readily attack the thyroid.
Thyroid Disrupting Chemicals
Stress can increase exposure to thyroid disrupting chemicals like BPA and phthalates found in plastic bottles, containers, and personal care products. This introduces thyroid interfering compounds.
Behavioral and Lifestyle Factors
Stress often leads to poor dietary, sleep, and exercise habits. Deficiencies in nutrients like iodine, selenium, and zinc can impair thyroid function. Disrupted circadian rhythms and sleep loss also disrupt hormones.
So in summary, through a variety of mechanisms, there are biologically plausible ways stress could contribute to hypothyroidism risk. But what does the research evidence actually indicate?
Research Evidence on Stress and Hypothyroidism
There have been a number of studies that have looked at the relationship between psychological stress and risk of developing hypothyroidism:
Animal Studies
– Rat studies have found chronic immobilization stress decreases T3 and T4 levels.
– Noise stress in rats impairs thyroid gland structure and function.
– Combined stress of cold exposure and restraint in rabbits reduces T3 and T4.
Human Correlational Studies
– Multiple studies show associations between PTSD, trauma, anxiety, and depression with increased risk for hypothyroidism.
– Stressful life events more common in Hashimoto’s thyroiditis patients.
– Chronic stress associated with higher TSH and lower free T4 levels indicating impaired thyroid function.
Human Intervention Studies
– Patients with hyperthyroidism who receive radioiodine treatment are more likely to develop hypothyroidism if they have high stress.
– After adjusting thyroid hormone dose post-thyroidectomy, patients with more stressful life events require higher dose.
– Stress management incorporating relaxation techniques improves thyroid function in hypothyroid patients on thyroid medication.
Limitations
– Animal models may not directly translate to humans
– Observational studies cannot prove causation due to potential confounding factors
– Stress interventions combined with other lifestyle changes
– Small sample sizes of some clinical studies
Conclusion
Based on the current research, there appears to be fairly consistent evidence that psychological stress negatively impacts thyroid function. Stress likely acts through multiple biological mechanisms to increase the risk of developing hypothyroidism. However, the majority of studies to date have been observational and animal research, so there is still a need for larger, controlled human studies specifically looking at stress reduction interventions.
It’s likely that stress alone does not directly cause hypothyroidism in most cases, but works in concert with other genetic and environmental factors to impair thyroid function. This means that while managing stress alone may not be enough to reverse hypothyroidism, it should be considered an important component of an overall treatment plan.
Stress reduction techniques like meditation, yoga, cognitive behavioral therapy and improving sleep, diet and exercise habits may help support healthy thyroid hormone levels. For individuals with hypothyroidism, being aware of and managing stress is likely an important consideration in achieving optimal thyroid function.
