Hypothyroidism

Hypothyroidism results from deficiency of the thyroid hormones thyroxine (T4) and triiodothyronine. Symptoms are diverse and not specific to thyroid disease. The most common causes are chronic autoimmune thyroid disease and destructive treatments for hyperthyroidism. The diagnosis is confirmed biochemically by a reduction in serum free T4 with increased serum thyroid-stimulating hormone (TSH; thyrotrophin). Subclinical hypothyroidism is a biochemical diagnosis and describes an elevated serum TSH with normal free thyroid hormones. Hypothyroidism is treated by T4 replacement, the aims of treatment being relief of symptoms and restoration of serum TSH to the reference range.