The thyroid gland is an endocrine gland in our body that functions to produce thyroid hormones, which are essential for maintaining our body’s metabolism. Thyroid hormones stimulate the cells in our body to produce proteins, which directly influence the body’s metabolism and the functions of various organs. Therefore, the secretion of thyroid hormones affects our heart rate, blood pressure, digestion, appetite, mood swings, bone metabolism, menstrual cycle, energy metabolism, and muscle control, etc. Both excessive (hyperthyroidism) and insufficient (hypothyroidism) secretion of thyroid hormones have significant effects on most organs in our body.

Hypothyroidism refers to the condition in which the thyroid gland produces too little thyroid hormone (T4 or T3) due to various reasons. As a result, the metabolism of various organs in the body slows down, leading to different clinical symptoms.

1. Hashimoto’s thyroiditis: Hashimoto’s thyroiditis is the most common cause of hypothyroidism. It occurs when the patient’s immune system malfunctions, leading to the production of abnormal antibodies that attack the thyroid cells and cause inflammation of the thyroid gland. In the early stages, patients may experience temporary hyperthyroidism, but in the long term, the destruction of thyroid tissue results in hypothyroidism.
2. Thyroidectomy: Hypothyroidism can occur when patients undergo total or subtotal thyroidectomy surgery and do not receive appropriate thyroid hormone replacement.
3. Radioactive iodine therapy: Hypothyroidism can develop in patients who undergo radioactive iodine therapy, as the excessive radiation kills off thyroid cells.
4. Radiation therapy side effects: Some patients with head and neck cancer who undergo radiation therapy may develop hypothyroidism as a side effect of the treatment, as the radiation can damage the thyroid cells.
5. Medications: Certain medications, such as lithium therapy, can cause hypothyroidism.
6. Congenital hypothyroidism: Conditions such as Cretinism can lead to congenital hypothyroidism.
7. Insufficient iodine intake: Hypothyroidism can occur due to inadequate dietary intake of iodine.
8. Other rare causes: Other less common causes of hypothyroidism include pituitary gland disorders and other underlying conditions.

When patients have insufficient secretion of thyroid hormones, leading to a slowed metabolism, they may experience the following symptoms:

1. Bradycardia (slow heart rate)
2. Sensitivity to cold
3. Fatigue and lethargy
4. Weakness in the limbs
5. Depression
6. Poor memory
7. Decreased appetite but noticeable weight gain
8. Menstrual irregularities
9. Constipation
10. High cholesterol levels in the blood

Due to the elevated cholesterol levels in the blood, patients are at a higher risk of developing cardiovascular complications such as coronary heart disease and stroke.

Blood Tests: Thyroid Function Tests

Thyroid function tests involve assessing the secretion of thyroid hormones in the body, which can be determined through blood tests. Thyroid function tests include measuring the levels of triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) in the blood.

Clinical Examination

Through physical examination and clinical assessment, doctors can inquire about the patient’s medical history, family history, and related symptoms. Clinical palpation allows the doctor to determine the presence of thyroid enlargement, the symmetry and uniformity of the thyroid swelling, the presence of other nodules or lymphadenopathy in the neck, and whether the trachea is compressed due to thyroid swelling. After the initial evaluation, the doctor may arrange for a thyroid ultrasound for further investigation.

Thyroid Ultrasound

Thyroid ultrasound is a non-invasive examination. During the procedure, the doctor applies gel to the patient’s neck and uses an ultrasound probe to obtain real-time images of the thyroid. The doctor captures corresponding images during the examination for evaluation. Thyroid ultrasound can help assess the size of the thyroid gland, the size and nature of thyroid lesions, blood flow around the lesions, identify calcifications, distinguish thyroid cysts and nodules, and evaluate whether there is lymphadenopathy in the neck, and other factors.

Doctors need to first identify the underlying cause of the patient’s condition before providing appropriate treatment.

Medication Therapy

Based on the patient’s thyroid hormone levels, the doctor will prescribe an appropriate dosage of thyroid hormone replacement medication to normalize their thyroid hormone levels. The patient may need to have regular blood tests to monitor their hormones levels. Additionally, if the patient requires surgery, develops other medical conditions, or becomes pregnant, the doctor may need to adjust the dosage of thyroid hormone replacement medication accordingly.