Hypothyroidism
What is Hypothyroidism?
Hypothyroidism is a condition in which the thyroid gland is underactive and produces insufficient thyroid hormones. Since these hormones regulate our metabolism, low hormone levels in the blood can lead to symptoms such as fatigue, tiredness, dry and thinning skin, and in untreated cases, an enlarged tongue and hoarse voice.
In blood tests, T3 and T4 levels are usually normal while TSH levels are elevated. If the disease is not controlled, patients begin to gain weight, body temperature drops over time, and mental clarity diminishes. Constipation is also a common symptom.
When these symptoms occur together, the patient should consult a specialist and have their thyroid function tested. If thyroid hormones are insufficient, treatment can be provided through daily hormone replacement tablets.
Causes of Hypothyroidism
Hypothyroidism is not a preventable disease and often occurs when the immune system attacks and damages the thyroid gland. The most well-known of these is Hashimoto’s thyroiditis, a chronic inflammation of the thyroid gland.
In Hashimoto’s disease, the immune system identifies the thyroid gland as foreign. It may sometimes do nothing for a lifetime or attack and destroy it, rendering it nonfunctional. Whether caused by Hashimoto’s or another disease, once hypothyroidism develops, the production of thyroid hormones that regulate metabolism decreases, leading to a variety of complaints.
Conditions like toxic goiter (overactive thyroid) and thyroid cancer can also impair thyroid function and reduce hormone secretion.
Other causes include:
- People with other autoimmune diseases like Type 1 diabetes or vitiligo
- Individuals who have had thyroid surgery or radioactive iodine treatment
- Congenital absence of the thyroid gland in babies (congenital hypothyroidism)
- Problems in the pituitary gland in the brain
- Living in iodine-deficient areas or consuming insufficient iodine
- Exposure to radiation
- Use of medications such as amiodarone, lithium, or interferon
- Family history of thyroid disorders
Women are 4 to 8 times more likely to develop this condition than men. While it is suspected that female hormones like estrogen and progesterone may play a role, there is no definitive evidence explaining why it is more common in women.
Symptoms of Hypothyroidism
Symptoms of underactive thyroid hormone production include:
- Fatigue, easy exhaustion, and slowed movements
- Depressed mood and unhappiness
- Intolerance to cold environments
- Swelling in hands and feet
- Reduced sweating
- Hoarseness
- Constipation
- Abnormal weight gain and increased appetite
- Forgetfulness and lack of concentration
- Delayed puberty in boys
- Decreased or absent menstruation in women
Diagnosis of Hypothyroidism
Diagnosis is made by checking hormone levels through a blood test called the thyroid function test.
In this test, TSH and T4 hormone levels are examined. High TSH and low T4 levels in the blood indicate hypothyroidism.
If TSH is high but T4 levels are normal, there is a risk of developing hypothyroidism in the future.
Your doctor will prepare a treatment plan using hormone replacement medication and monitor your thyroid levels with regular blood tests.
In addition to hormone levels, physical examination for swelling, family history of thyroid disease, difficulty swallowing, or bulging eyes may prompt an ultrasound to assess the size and structure of the gland.
Detection of a nodule does not necessarily mean it is malignant. Further investigations may include a thyroid scan or fine-needle aspiration biopsy if necessary.
Treatment of Hypothyroidism
When the body has insufficient T4 hormone, the deficiency is corrected through hormone replacement therapy. However, hypothyroidism is not a temporary condition and requires lifelong treatment.
Symptoms usually begin to improve within two weeks after starting thyroid medication. Treatment starts with a low dose and is gradually increased every 5–6 weeks until the TSH level normalizes. Afterwards, blood levels are usually checked every six months or annually to ensure hormone levels remain stable.
Pregnant women, elderly patients, and those with coronary artery disease require more frequent monitoring because thyroid hormone medications can increase heart rate, so dosage adjustments must be made carefully.
If untreated, lifelong hypothyroidism can lead to ongoing metabolic issues resulting in serious and potentially fatal complications like heart enlargement, heart failure, blood clots, high blood pressure, and atherosclerosis.
If blood tests reveal thyroid hormone deficiency but symptoms are very mild, treatment may not be immediately necessary. In such cases, your doctor may monitor hormone levels every few months.