Hypothyroidism is treated with synthetic thyroxine, which is identical to the T4 made by the thyroid. The exact dose will depend on the patient’s age and weight, the severity of the hypothyroidism, the presence of other health problems, and whether the person is taking other drugs that might interfere with how well the body uses thyroid hormone.
Health care providers test TSH levels about 6 to 8 weeks after a patient begins taking thyroid hormone and make any necessary adjustments to the dose. Each time the dose is adjusted, the blood is tested again. Once a stable dose is reached, blood tests are normally repeated in 6 months and then once a year after that.
Hypothyroidism can almost always be completely controlled with synthetic thyroxine, as long as the recommended dose is taken every day as instructed.
Further Reading
Source: National Endocrine and Metabolic Diseases Information Service