How is it used?TSH testing is used to:
diagnose a thyroid disorder in a person with symptoms,
screen newborns for an underactive thyroid,
monitor thyroid replacement therapy in people with hypothyroidism,
diagnose and monitor female infertility problems, and
screen adults for thyroid disorders as recommended by some organizations, such as the American Thyroid Association.

When is it ordered? Your doctor orders this test if you show symptoms of a thyroid disorder. For example, symptoms of hyperthyroidism include heat intolerance, weight loss, rapid heartbeat, nervousness, insomnia, and breathlessness.

Common symptoms of hypothyroidism include fatigue, weakness, weight gain, slow heart rate, and cold intolerance.

The blood test may be ordered with other thyroid hormone tests and after a physical examination of your thyroid. TSH screening is routinely performed in newborns. The American Thyroid Association recommends that adults older than age 35 be screened for thyroid disease every five years although other organizations, such as the U.S. Preventive Services Task Force, challenge this recommendation. Several organizations recommend instead screening women over 50, asymptomatic adults over 60, or those at high risk for thyroid disorders, such as pregnant and postpartum women.