Signs and Symptoms of Hypothyroidism - Poor ability to tolerate cold - Feeling tired - Constipation - Weight gain - Swelling of the front part of the neck due to goitre

Diagnosis and Treatment of Hypothyroidism - Blood tests measuring thyroid-stimulating hormone (TSH) and thyroxine levels confirm the diagnosis - Salt iodization has helped prevent hypothyroidism in many populations - Thyroid hormone replacement with levothyroxine is the main treatment - Dose adjustment is based on symptoms and normalization of thyroxine and TSH levels - Thyroid medication is safe during pregnancy

Prevalence and Demographics of Hypothyroidism - Worldwide, iodine deficiency in the diet is the most common cause of hypothyroidism - Hashimoto's thyroiditis is the most common cause in countries with sufficient dietary iodine - Other causes include previous treatment with radioactive iodine, hypothalamus or anterior pituitary gland injury, certain medications, lack of a functioning thyroid at birth, or previous thyroid surgery - About one billion people worldwide are estimated to be iodine-deficient - In the United States, hypothyroidism occurs in 0.3-0.4% of people

Effects of Hypothyroidism on Pregnancy - Untreated hypothyroidism during pregnancy can lead to delays in growth and intellectual development in the baby - Even mild or subclinical hypothyroidism can increase the risk of infertility and miscarriage - Hypothyroidism in early pregnancy may increase the risk of pre-eclampsia and lower intelligence in offspring - Subclinical hypothyroidism during pregnancy is associated with gestational diabetes, low birth-weight, placental abruption, and preterm birth - Hypothyroidism affects 0.3-0.5% of pregnancies in women

Related Disorders and Complications of Hypothyroidism - Thyroid hormone abnormalities are common in major psychiatric disorders, such as bipolar disorder, mood disorders, and schizophrenia-spectrum disorders - Screening for thyroid dysfunction is recommended among individuals with psychiatric disorders - Myxedema coma is a rare but life-threatening state of extreme hypothyroidism - Myxedema coma can occur in those with established hypothyroidism during acute illness - Myxedema coma is characterised by low body temperature, confusion, slow heart rate, reduced breathing effort, and physical signs of hypothyroidism