Hypothyroidism

About Hypothyroidism

Hypothyroidism, or underactive thyroid, occurs when the thyroid gland does not produce enough thyroid hormones T4 and T3. The most common cause globally is iodine deficiency, though this has decreased with salt iodization programs. In iodine sufficient countries, Hashimotos thyroiditis, an autoimmune condition, is the most common cause. Other causes include thyroid surgery, radioactive iodine treatment for hyperthyroidism, medications lithium, amiodarone, and pituitary disease secondary hypothyroidism. Symptoms develop gradually and include fatigue, weight gain, cold intolerance, dry skin, hair loss, constipation, muscle weakness, depression, memory problems, slowed heart rate, and in women, irregular menstrual periods. Severe untreated hypothyroidism can cause myxedema coma, a medical emergency. Diagnosis is made through blood tests showing elevated TSH and low free T4. Subclinical hypothyroidism has elevated TSH with normal T4. Treatment is with levothyroxine synthetic T4, adjusted based on TSH levels. Most patients require lifelong treatment. During pregnancy, thyroid requirements increase and hypothyroidism must be carefully managed to prevent fetal complications.