Some organizations (such as the United States Preventive Services Task Force) state that evidence is insufficient to support routine screening, while others (such as the American Thyroid Association) recommend either intermittent testing above a certain age in all sexes or only in women. Targeted screening may be appropriate in a number of situations where hypothyroidism is common: other autoimmune diseases, a strong family history of thyroid disease, those who have received radioiodine or other radiation therapy to the neck, those who have previously undergone thyroid surgery, those with an abnormal thyroid examination, those with psychiatric disorders, people taking amiodarone or lithium, and those with a number of health conditions (such as certain heart and skin conditions). Yearly thyroid function tests are recommended in people with Down syndrome, as they are at higher risk of thyroid disease. Guidelines for England and Wales from the National Institute for Health and Care Excellence (NICE) recommend testing for thyroid disease in people with type 1 diabetes and new-onset atrial fibrillation, and suggests testing in those with depression or unexplained anxiety (all ages), in children with abnormal growth, or unexplained change in behaviour or school performance. On diagnosis of autoimmune thyroid disease, NICE also recommends screening for celiac disease. Management
Hormone replacement
Most people with hypothyroidism symptoms and confirmed thyroxine deficiency are treated with a synthetic long-acting form of thyroxine, known as levothyroxine (L-thyroxine).
There may be other features of hypopituitarism, such as menstrual cycle abnormalities and adrenal insufficiency. There might also be symptoms of a pituitary mass such as headaches and vision changes. Central hypothyroidism should be investigated further to determine the underlying cause. Overt
In overt primary hypothyroidism, TSH levels are high and T4 and T3 levels are low. Overt hypothyroidism may also be diagnosed in those who have a TSH on multiple occasions of greater than 5mIU/L, appropriate symptoms, and only a borderline low T4. It may also be diagnosed in those with a TSH of greater than 10mIU/L. Subclinical
Subclinical hypothyroidism is a milder form of hypothyroidism characterized by an elevated serum TSH level, but with a normal serum free thyroxine level. This milder form of hypothyroidism is most commonly caused by Hashimotos thyroiditis. In adults it is diagnosed when TSH levels are greater than 5 mIU/L and less than 10mIU/L. The presentation of subclinical hypothyroidism is variable and classic signs and symptoms of hypothyroidism may not be observed. Of people with subclinical hypothyroidism, a proportion will develop overt hypothyroidism each year. In those with detectable antibodies against thyroid peroxidase (TPO), this occurs in 4.3%, while in those with no detectable antibodies, this occurs in 2.6%. Those with subclinical hypothyroidism and detectable anti-TPO antibodies who do not require treatment should have repeat thyroid function tests more frequently (e.g. yearly) compared with those who do not have antibodies.