Cracking the Code: Uncovering the Hidden Causes of Persistent Fatigue and Unexplained Weight Changes

There is a saying that goes, “You only realize the value of health after you lose it.” It means that there is nothing more precious than living happily and healthily. Through ‘Etoday Health~Ssok (eHealth~Ssok)’ with domestic medical staff, we introduce useful health information that will be helpful if you know it in your daily life.

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#Ms. J, a woman in her 70s, was diagnosed with hypothyroidism after undergoing tests due to cognitive decline to the point where she could not even remember recent conversations. Mr. P, a man in his 60s, was treated for arrhythmia, but was also diagnosed with hyperthyroidism and decided to receive medication. Let’s learn about thyroid dysfunction that threatens the brain and heart.

The thyroid gland is an organ that secretes hormones that control the body’s metabolism. If there is a problem with the thyroid function, hypothyroidism or hyperthyroidism occurs, in which hormones are either insufficient or excessively secreted. It may start with mild symptoms at first, but if left untreated, serious complications can occur.

Professor Cho Yoon-young of the Department of Endocrinology and Metabolism at Soonchunhyang University Bucheon Hospital explained, “Hypothyroidism can cause cardiovascular disease due to cholesterol accumulation, and is closely related to dopamine secretion, which can lead to mood disorders, sleep disorders, and cognitive disorders.” Professor Cho continued, “Hyperthyroidism is known to increase the mortality rate due to heart disease such as arrhythmia and heart failure by increasing heart rate and cardiac output, and it is also known to increase the risk of stroke.”

According to the medical community, the incidence of hypothyroidism was 118 per 100,000 people in 2018, an increase of more than 60% compared to 2003. 83% of hypothyroidism occurs in women, and the prevalence increases with age. It is estimated that the incidence has increased due to the aging population and increased early detection. On the other hand, the incidence of hyperthyroidism decreased from the early 2000s to 40 per 100,000 people in 2018, and more than two-thirds are women and occur at a relatively young age.

In fact, according to the National Health Insurance Service’s disease statistics on the 31st, the number of patients treated for hypothyroidism (inpatients and outpatients) has increased by about 92,000 since 2019. It increased from 592,310 in 2019 to 644,104 in 2021 and 684,529 last year.

The number of patients with hyperthyroidism has increased and decreased repeatedly over the past five years. It decreased from 364,579 in 2019 to 254,378 in 2020, then increased to 263,930 in 2021 and 266,834 in 2022. Then, it decreased slightly again to 262,197 last year.

Hypothyroidism causes all metabolisms to slow down, leading to symptoms such as lethargy, lack of concentration, weight gain, and swelling. A representative example is Hashimoto’s thyroiditis, a chronic autoimmune disease.

Hyperthyroidism is characterized by symptoms such as increased metabolism and heart rate, palpitations, excessive sweating, tremors, shortness of breath, irritability, and weight loss despite eating the same amount.

Blood tests and thyroid autoantibody tests are performed to diagnose thyroid dysfunction. Thyroid ultrasound may be performed if the thyroid gland is swollen or if subacute thyroiditis needs to be differentiated. If the cause is unclear, a thyroid scan may be performed.

Professor Cho Yoon-young said, “Treatment for hypothyroidism is mainly thyroid hormone replacement. Thyroid hormone drugs have a long half-life, so they are stable and safe enough to be taken during pregnancy and breastfeeding. More than 40% of patients with hypothyroidism in Korea require long-term treatment for more than three years, and regular thyroid function tests should be performed to maintain appropriate drug concentrations.” She advised, “In particular, if the patient had other long-term complications, such as heart failure, at the time of diagnosis, it is necessary to maintain thyroid hormones for a long period of time.”

Treatment for hyperthyroidism includes drug therapy, radioisotope therapy, and surgery. In Korea, drug therapy is performed preemptively because it is relatively safe and has less burden on patients, but it has the disadvantage of frequent relapse. If severe side effects occur or the treatment effect is low in drug therapy, secondary treatment such as radioisotope or surgery, which has a higher cure rate than drug therapy, is attempted. In this case, when remission is reached, it usually changes to hypothyroidism, so hormone replacement is necessary.

Professor Cho said, “If a patient with hypothyroidism plans to become pregnant, they should consult with the appropriate doctor in charge to check if their thyroid function is appropriate, and during pregnancy, they should increase the dose of hormone medication to match the increased thyroid hormone demand. Hyperthyroidism can also become pregnant if the thyroid function is well controlled with medication, and they should consult with their doctor in advance because they should change to a safer medication.”

If you have a family history of thyroid dysfunction, you should definitely consider the possibility of thyroid dysfunction and get tested. Environmental factors include iodine intake, viral infections, and stress. If you are taking medication for thyroid dysfunction, you should limit excessive iodine intake.

Professor Cho Yoon-young emphasized, “Many young patients with hyperthyroidism skip taking their medication or miss hospital visits due to their busy social lives. Uncontrolled hyperthyroidism increases the risk of cardiovascular complications such as arrhythmia and heart failure by 1.5 to 3 times, so regular hospital visits and consistent medication are important. If you have persistent fatigue or unexplained weight changes, you should consider a thyroid function test.”