Overview
Hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormones (T3, T4). Thyroid hormones regulate many vital functions such as metabolism, energy production, heart rate, and body temperature.
It affects about 5-10% of adults; it is 5-8 times more common in women than in men. The most common cause is an autoimmune disease called Hashimoto's thyroiditis.
Symptoms
Symptoms usually develop slowly, over months or even years:
- Fatigue, weakness
- Cold intolerance, feeling cold
- Unexplained weight gain
- Dry skin, dry hair, hair loss
- Constipation
- Muscle and joint aches
- Muscle weakness, cramps
- Facial puffiness, especially around the eyelids
- Thick, hoarse voice
- Low heart rate (bradycardia)
- Heavy or irregular menstrual bleeding
- Depression, mood changes
- Memory and concentration problems
- High cholesterol
- Infertility or pregnancy complications
- Goiter (swelling in the neck)
Causes
- Hashimoto's thyroiditis (most common cause, autoimmune)
- Thyroid surgery
- Radioactive iodine therapy
- Radiation therapy to the neck
- Iodine deficiency (reduced with iodized salt use)
- Some medications: Lithium, amiodarone, interferon
- Congenital hypothyroidism
- Pituitary or hypothalamic disorders (central hypothyroidism)
- Postpartum thyroiditis
Risk Factors
- Being female
- Being 60 or older
- Family history
- Presence of autoimmune disease (Type 1 diabetes, celiac)
- Previous thyroid disease or surgery
- Radiation therapy to the neck
- Pregnancy or postpartum within the last 6 months
- Down syndrome, Turner syndrome
Complications
- Goiter (thyroid enlargement)
- Heart problems (heart failure, pericardial effusion)
- High cholesterol
- Peripheral neuropathy
- Myxedema (in very severe cases)
- Myxedema coma (emergency, life-threatening)
- Infertility, miscarriage
- Brain development issues in unborn babies
- Cretinism in newborns
- Depression
When to See a Doctor
- If you have several of the symptoms
- Persistent fatigue, weight gain, dry skin, cold feeling
- If you notice swelling in your neck
- If you have a family history of thyroid disease
- If you are or are planning to become pregnant
- Regular check-ups are essential if you are on thyroid medication
Diagnosis and Treatment
Diagnosis:
- TSH (elevated, most sensitive test)
- Free T4 (low)
- Anti-TPO and anti-thyroglobulin antibodies (for Hashimoto's)
- Thyroid ultrasound
Treatment:
- Levothyroxine (synthetic T4 hormone) replacement therapy
- Tablet taken on empty stomach, 30-60 minutes before breakfast
- Should be separated from iron, calcium, magnesium supplements
- Treatment is usually lifelong
- Dose is individual; adjusted with regular TSH monitoring
- Dose adjustments every 6-8 weeks, then once or twice a year
- Dose may need to be increased during pregnancy
Prevention and Lifestyle
- Consume adequate iodine (use iodized salt)
- Pay attention to selenium, zinc, and vitamin D balance
- Take your medications regularly; do not stop on your own
- Get regular blood tests
- Quit smoking
- More frequent screening if there is a history of autoimmune disease
- If planning pregnancy, have your TSH checked in advance
- Do not skip newborn screening tests (heel prick)